Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
METHOD AND APPARATUS FOR NEURAL-SIGNAL CAPTURE TO
DRIVE NEUROPROSTHESES OR CONTROL BODILY FUNCTION
CROSS-REFERENCE TO RELATED APPLICATIONS
[001] This application claims priority to U.S. Provisional Patent Application
61/081,732
(Attorney Docket 5032.044PV1) filed on July 17, 2008, titled "Method and
Apparatus for
Neural Signal Capture to Drive Neuroprostheses or Bodily Function," and to
U.S. Provisional
Patent Application 61/226,661 (Attorney Docket 5032.044PV2) filed on July 17,
2009, titled
"Method and Apparatus for Neural-Signal Capture to Drive Neuroprostheses or
Control Bodily
Function," each of which is incorporated herein by reference in its entirety.
[002] This invention is also related to U.S. Patent Application Serial Number
11/257,793
filed October 24, 2005 (Attorney Docket No. 5032.009US1) titled "Apparatus and
Method for
Optical Stimulation of Nerves and Other Animal Tissue," U. S. Patent
Application Serial
Number 11/536,639 filed September 28, 2006 (Attorney Docket No. 5032.02OUS1)
and titled
"MINIATURE APPARATUS AND METHOD FOR OPTICAL STIMULATION OF NERVES
AND OTHER ANIMAL TISSUE," U.S. Patent Application Serial Number 11/948,912
filed
November 30, 2007 (Attorney Docket No. 5032.022US1) and titled "APPARATUS AND
METHOD FOR CHARACTERIZING OPTICAL SOURCES USED WITH HUMAN AND
ANIMAL TISSUES," U.S. Patent Application Serial Number 11/536,642 filed
September 28,
2006 (Attorney Docket No. 5032.023US1) and titled "APPARATUS AND METHOD FOR
STIMULATION OF NERVES AND AUTOMATED CONTROL OF SURGICAL
INSTRUMENTS," U.S. Patent Application Serial Number 11/971,874 filed January
9, 2008
(Attorney Docket No. 5032.026US1) and titled "METHOD AND VESTIBULAR IMPLANT
USING OPTICAL STIMULATION OF NERVES," U.S. Provisional Patent Application
Serial
Number 12/191,301 filed August 13, 2008 (Attorney Docket No. 5032.038US1) and
titled
"VCSEL ARRAY STIMULATOR APPARATUS AND METHOD FOR LIGHT
STIMULATION OF BODILY TISSUES," U.S. Provisional Patent Application Serial
Number
12/254,832 filed October 20, 2008 (Attorney Docket No. 5032.039US1) and titled
"SYSTEM
AND METHOD FOR CONDITIONING ANIMAL TISSUE USING LASER LIGHT," and U.S.
Provisional Patent Application Serial Number 61/015,665 filed December 20,
2007 (Attorney
Docket No. 5032.041PV1) and titled "LASER STIMULATION OF THE AUDITORY
SYSTEM AT 1.94 gM AND MICROSECOND PULSE DURATIONS," each of which is
incorporated herein by reference in its entirety.
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FIELD OF THE INVENTION
[003] The invention relates generally to the detection of neural activity
using optics and
more particularly to methods and apparatus for neural signal capture used to
drive
neuroprostheses or to stimulate or control bodily function.
BACKGROUND OF THE INVENTION
[004] Various strategies exist for detecting neural activity using light. For
example, axonal
swelling can be monitored based on passive movement of water across cell
membranes as ions
flow during an action potential (e.g., phase-sensitive optical low-coherence
reflectometry).
[005] Attached to the end of U.S. Provisional Patent Application 61/081,732
(Attorney
Docket 5032.044PV1) filed on July 17, 2008, titled "METHOD AND APPARATUS FOR
NEURAL SIGNAL CAPTURE TO DRIVE NEUROPROSTHESES OR BODILY
FUNCTION," which is incorporated herein by reference in its entirety, are two
appendices
which include detailed studies of neural-signal capture. Both of these
appendices are
incorporated herein by reference in their entirety. Appendix A is titled
"Effects of measurement
method, wavelength, and source-detector distance on the fast optical signal,"
and is authored by
Gabriele Gratton et al. Appendix B is titled "Progress of near-infrared
spectroscopy and
topography for brain and muscle clinical applications," and is authored by
Martin Wolf et al. In
some embodiments, the present invention uses techniques and apparatus such as
described in
these references in the improved invention described herein.
[006] Another neural-activity-detection strategy involves spectroscopically
analyzing
chemical concentrations that mediate action potentials (AP's). Examples
include analyzing
increases in oxygen (02) consumption in the brain, monitoring concentrations
of molecules that
fluoresce (e.g., flavin adenine dinucleotide (FAD), nicotinamide adenine
dinucleotide (NADH),
etc.) using fluorescence spectroscopy, and monitoring concentrations of other
molecules
involved in action potential (e.g., free intracellular Cat+, free
neurotransmitters, etc.).
Fluorescence spectroscopy can target molecules/proteins involved in the
transduction or
propagation of an action potential (directly or indirectly, such as blood
flow). Optical coherence
tomography can also be used to detect potentials (via changes in blood flow or
membrane
movement-leading to fast scattering changes).
[007] There are recent descriptions of research as to the sources of human
volition, which
are based on electrical stimulation of the brain during surgery when the skull
is open and the
brain exposed. See, e.g., Haggard, "The Sources of Human Volition", Science, 8
May 2009,
Vol. 324: pp 731-733 and Desmurget et al., "Movement Intention after Parietal
Cortex
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Stimulation in Humans," Science, 8 May 2009, Vol. 324: pp 811-813, each of
which is
incorporated by reference. Desmurget et al. describe electrically stimulating
patients, each being
stimulated at a number of sites in the frontal, parietal and temporal regions
on the exposed brain
surface of the patients, and determining various particular Brodmann area (BA)
sites, which,
when stimulated, produced a desire to move (and/or a sensation that a movement
had been
accomplished) without any overt movement being produced.
[008] Various cortical area-to-function mapping schemes exist. One mapping is
based on
Brodmann areas, which are regions of the cortex defined based on their
cytoarchitecture, or
organization of cells. Brodmann areas (BAs) were originally defined and
numbered by
Korbinian Brodmann in 1909. Such mapping relies on the notion that certain
areas of the brain
(e.g., BAs) are dedicated to particular functions, such as action execution
(e.g., sending signals
to muscles to move, or for speech), action inhibition, action observation,
action preparation, or
action motor learning. Other brain areas (e.g., BAs) are dedicated to
cognition (including
attention, of language, language orthography, language phonology, language
semantics,
language speech, language syntax, memory explicit, memory implicit, memory-
working, music,
reasoning, soma, space, and time), emotion (including anger, anxiety, disgust,
fear, sadness),
interoception (including of hunger and sexuality), perception (including
audition, olfaction,
somesthesis, and pain), and perception vision (including of color, motion, and
shape).
[009] U.S. Patent 5,213,105 to Gratton, et al. that issued May 25, 1993 is
titled "Frequency
domain optical imaging using diffusion of intensity modulated radiation" and
is incorporated
herein by reference. This patent describes arrangements for producing images
based upon
diffusional-wave theory and frequency-domain analysis. A medium to be imaged
is illuminated
with amplitude modulated radiation, and diffusional radiation transmitted or
reflected by the
medium is detected at a plurality of detection locations, as by a television
camera. The phase
and also the amplitude demodulation of the amplitude modulated diffusional
radiation are
detected at each detection location. A relative phase image and also a
demodulation amplitude
image of the medium are then generated from respectively the detected relative
phase values and
the detected demodulation amplitudes of the diffusional radiation at the
plurality of locations.
The body is illuminated with near infrared radiation (NIR) having a wavelength
between 600
and 1200 nanometers that is amplitude modulated at a frequency in the
megahertz to gigahertz
range, and internal images of the patient are generated for medical diagnosis.
[0010] U.S. Patent 5,088,493 to Giannini, et al. that issued February 18, 1992
titled
"Multiple wavelength light photometer for non-invasive monitoring" is
incorporated herein by
reference. This patent describes a multiple wavelength light spectrophotometer
for non-invasive
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monitoring of a body organ in vivo including: a single pulsed light source,
optical fibers for
transmitting to and receiving the infrared radiation from the organ, a
radiation detector capable
of branching received radiation into several different wavelengths, an
amplifier, and a data
acquisition system including a microprocessor capable of compensating for
light-diffusion
effects by employing a specific algorithm.
[0011] U.S. Patent 5,564,417 to Chance that issued October 15, 1996 titled
"Pathlength
corrected oximeter and the like" is incorporated herein by reference. This
patent describes a
path-length-corrected spectrophotometer for tissue examination that includes
an oscillator for
generating a carrier waveform of a selected frequency, an LED light source for
generating light
of a selected wavelength that is intensity modulated at the selected frequency
introduced to a
subject, and a photodiode detector for detecting light that has migrated in
the tissue of the
subject. The spectrophotometer also includes a phase detector for measuring a
phase shift
between the introduced and detected light, a magnitude detector for
determination of light
attenuation in the examined tissue, and a processor adapted to calculate the
photon migration
path length and determine a physiological property of the examined tissue
based on the path
length and on the attenuation data.
[0012] A survey paper by Peter Rolfe titled "In Vivo Near-Infrared
Spectroscopy" Annu.
Rev. Biomed. Eng. 2000. 02:715-54 is incorporated herein by reference. In this
paper, Rolfe
described various methods for determining the spatial location of structures
and activities in a
living person, including analysis of propagation in tissue, in vivo
multivariate analysis, time-
resolved spectroscopy, time-domain methods, frequency domain methods, and
spatially resolved
spectroscopy. Rolfe notes that light scattering has two possible forms,
elastic and inelastic.
With inelastic scattering, the incident energy is absorbed by the scatterer,
and energy at a
different wavelength is then emitted as the excited molecule falls back to one
of several
alternative states. This may lead to fluorescence or phosphorescence, for
example. With elastic
scattering, however, there is no loss of energy, but the re-emitted energy
merely moves on in a
different direction than that of the incoming energy. In tissues, it is
possible for both elastic and
inelastic scattering to take place when NIR wavelengths are used for
interrogation, although
most early work has been concerned with the use of elastic scattering
phenomena. Early in the
development of in vivo near-infrared spectroscopy (ivNIRS), it was apparent
that the difference
between physical (geometrical)-path length, L, and optical-path length, Lo,
has a profound effect
on calculations of chemical concentration made by using the simple Lambert-
Beer law. A
correction for this effect could be made if a path length factor ~ is applied
to the physical-path
length measurement L,, - ~ L. Applying that analysis to a tissue sample in
which scattering
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takes place, extending the path length from L to Lo by an amount that is
determined from the
differential-path-length factor ~. Determination of ~ for a tissue sample
allows this aspect of
scatter to be accounted for, and this approach was indeed carried out by
several groups (Wyatt
JS, et al. 1990, "Measurement of optical path length for cerebral near
infrared spectroscopy in
newborn infants," Dev. Neurosci. 12:140-44). However, this is not the whole
story, because the
Lambert-Beer law must be modified appropriately to add a scattering term G,
which depends on
the nature of the tissues and geometry: A = log(I/lo) = s[C]L + G. Absolute
quantitative
concentration cannot be obtained without knowledge of G. However, partly to
overcome this
difficulty, assumptions may be made that the effect of scatter remains
constant, and therefore the
additional scattering term can be eliminated by mathematical manipulations.
This approach led
to the use of multivariate analysis to determine quantitative measurement of
changes in absorber
concentration [AC] from changes in absorption AA. The precise wavelengths used
in NIRS
instruments vary somewhat, as is described below. In the earlier instruments
developed by
Rolfe's group, the wavelengths used were 775, 845, and 904 nm. An additional
wavelength of
805 nm was also used for some experimental work. Changes in concentration of
each oxygen-
dependent absorber, [AC], can then be calculated, where the extinction
coefficients for each
chromophore at each of the three wavelengths are specified. This set of
equations can then be
used to obtain the change in concentration of each of the three absorbers. As
a first
approximation, it is assumed that ~ is the same for the three wavelengths. The
s,;j values have
been determined in vitro by using laboratory spectrophotometers (see Van
Assendelft OW,
"Spectrophotometry of Haemoglobin Derivatives," Assen, The Netherlands:
Vangorcum, 1970;
Rea PA, Crowe J, Wickramasinghe Y, Rolfe P, "Non-invasive optical methods for
the study of
cerebral metabolism in the human newborn: a technique for the future?" J Med.
Eng. Technol.
9(4):160-66, 1985; Wray S, Cope M, Delpy DT, Wyatt JS, Reynolds EOR,
"Characterisation of
the near infra-red absorption spectra of cytochrome aa3 and haemoglobin for
the non invasive
monitoring of cerebral oxygenation," Biochim. Biophys. Acta 933:184-92, 1988).
The distance
traveled by scattered photons between the transmitter and the receiver is
longer than that
traveled by unscattered photons. Approaches based on time-resolved
spectroscopy (Chance B,
Leigh JS, Miyake M, Smith DS, Nioka S, et al. "Comparison of time-resolved and
-unresolved
measurements of deoxyhemoglobin in brain," Proc. Natl. Acad. Sci. USA 85:4971-
75, 1988;
Patterson MS, Chance B, Wilson BC, "Time resolved reflectance and
transmittance for the
noninvasive measurement of tissue optical properties," Appl. Opt. 28:2331-36,
1989) include
time-domain (TD) and frequency-domain (FD) methods. These methods were
reviewed, and the
theoretical basis for their operation was described thoroughly, by Arridge SR,
Cope M, Delpy
DT, "The theoretical basis for the determination of optical pathlengths in
tissue: temporal and
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frequency analysis," Phys. Med. Biol. 37(7):1531-60, 1992). Here the path-
length factor
introduced above, ~ , is referred to as the differential path length factor.
With the TD method, a
short light pulse (about 2-5 ps) is delivered to the sample and, after
propagation, is detected
with, for example, a streak camera (Delpy DT, Cope M, van der Zee P, Arridge
SR, Wray S,
Wyatt JS, "Estimation of optical pathlength through tissue from direct time of
flight
measurement," Phys. Med. Biol. 33(12):1433-42, 1988). The family of photon
paths produced
by scattering leads to a broadening of the pulse with the temporal point
spread function (TPSF).
The time tmax at which the maximum detected intensity occurs relative to the
input pulse is the
mean arrival time of photons, and this may be used, together with velocity of
light in vacuo (co)
and tissue refractive index nt to calculate mean optical path length =
(cõ/nt)tmax. Use of the
measurement of time gives the method its alternative name, "time-of-flight."
Although the TD
method is a valuable tool for conducting basic research, the apparatus is
large and expensive and
not directly suited to clinical monitoring. The FD approach has the potential
to overcome this
problem. In FD spectroscopy, the interrogating energy is intensity modulated
(IM), and the
detected energy exhibits a phase shift, 1, as compared with the modulating
signal, owing to the
propagation delay, as well as attenuation from absorption and scattering. The
detected intensity
is of the form: I = Id, + Iac sin(2 7rvt q)). The measurement of q) can allow
optical path length
to be calculated because L. = q) cT, / 2 lrvnt ; where v is the modulating
frequency, nt is the
refractive index of the tissue, and cT, is the speed of light in vacuo.
Because phase measurement
is used in this way, the approach is also referred to as "phase modulation"
(Chance B, Maris M,
Sorge J, Zhang MZ, "A phase modulation system for dual wavelength difference
spectroscopy
of hemoglobin deoxygenation in tissues," Proc. SPIE 1204:481-91, 1990; Weng J,
Zhang MZ,
Simons K, Chance B, "Measurement of biological tissue metabolism using phase
modulation
spectroscopic techniques," Proc. SPIE 1431: 161-70, 1991). Measurement of
tissue-absorption
and scattering coefficients can also be achieved by means of a further
evolution of FD methods.
This approach overlaps with the concepts and techniques referred to as
spatially resolved (SR)
methods below. Fishkin & Gratton solved the diffusion equation by considering
a homogeneous
infinite medium and assuming that the modulation frequency is much smaller
than the typical
frequency of scattering processes (Fishkin JB, Gratton E, "Propagation of
photon-density waves
in strongly scattering media containing an absorbing semi-infinite plane
bounded by a straight
edge," J. Opt. Soc. Am. A 10:127-40, 1993; Fishkin JB, So PTC, Cerussi AE,
Fantini S,
Franceschini MA, Gratton E, "Frequency-domain method for measuring spectral
properties in
multiple-scattering media: methemoglobin absorption spectrum in a tissue-like
phantom," Appl.
Opt. 34(7):1143-55, 1995). Spatially resolved spectroscopy (SRS) addresses the
practical
difficulty presented by very high absorbance during attempts to make
measurements through
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thick tissue sections has undoubtedly led to increased efforts to gain more
information from
reflection, diffuse reflection, or backscatter measurements. In this mode, the
input-output sites
on the tissue are adjacent, and their spacing may be controlled to ensure
adequate signal levels
for reliable analysis. Much work has therefore been done to develop further
the fundamental
photon propagation relationships so that they can be applied to a variety of
reflection/backscatter
configurations. This is relevant to multisite measurement, sometimes called
multi-distance
spectroscopy, which is of growing importance. The SR method is based on
solution of the
diffusion approximation for a highly scattering medium. Patterson et al.
(Patterson MS, Chance
B, Wilson BC, "Time resolved reflectance and transmittance for the noninvasive
measurement
of tissue optical properties," Appl. Opt. 28:2331-36, 1989) solved this
problem with a semi-
infinite half-space geometry for an input-function. See also Matcher SJ,
Kirkpatrick P, Nahid K,
Cope M, Delpy DT, "Absolute quantification methods in tissue near infrared
spectroscopy,"
Proc. SPIE 2389:486-95, 1995.
[0013] A number of patents describe various aspects of NIR spectroscopy,
including U.S.
Patent 4,768,516 by Stoddart et al. issued September 6, 1988 titled "Method
and apparatus for in
vivo evaluation of tissue composition," U.S. Patent 4,972,331 by Chance issued
November 20,
1990 titled "Phase modulated spectrophotometry," U.S. Patent 5,122,974 by
Chance issued June
16, 1992 titled "Phase modulated spectrophotometry," U.S. Patent 5,139,025 by
Lewis, et al.
issued August 18, 1992 titled "Method and apparatus for in vivo optical
spectroscopic
examination," U.S. Patent 5,187,672 by Chance, et al. issued February 16, 1993
titled "Phase
modulation spectroscopic system," U.S. Patent 5,213,105 by Gratton, et al.
issued May 25, 1993
titled "Frequency domain optical imaging using diffusion of intensity
modulated radiation," U.S.
Patent 5,386,827 by Chance, et al. issued February 7, 1995 titled
"Quantitative and qualitative in
vivo tissue examination using time resolved spectroscopy," U.S. Patent
5,402,778 by Chance
issued April 4, 1995 titled "Spectrophotometric examination of tissue of small
dimension," U.S.
Patent 6,246,892 by Chance issued June 12, 2001 titled "Phase modulation
spectroscopy," U.S.
Patent 6,263,221 by Chance, et al. issued July 17, 2001 titled "Quantitative
analyses of
biological tissue using phase modulation spectroscopy," U.S. Patent 6,272,367
by Chance issued
August 7, 2001 titled "Examination of a biological tissue using photon
migration between a
plurality of input and detection locations," U.S. Patent 6,542,772 by Chance
issued April 1,
2003 titled "Examination and imaging of biological tissue," U.S. Patent
6,564,076 by Chance
issued May 13, 2003 titled "Time-resolved spectroscopic apparatus and method
using streak
camera," U.S. Patent 6,956,650 by Boas, et al. issued October 18, 2005 titled
"System and
method for enabling simultaneous calibration and imaging of a medium," U.S.
Patent 7,139,603
by Chance issued November 21, 2006 titled "Optical techniques for examination
of biological
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tissue," U.S. Patent Application 20080009748 Al by Enrico Gratton et at.
published January 10,
2008 titled "Method And Apparatus for the Determination of Intrinsic
Spectroscopic Tumor
Markers by Broadband-Frequency Domain Technology," U.S. Patent Application
20080161697
Al by Chance; Britton published July 3, 2008 titled "Examination of subjects
using photon
migration with high directionality techniques," U.S. Patent Application
20090030327 Al by
Chance; Britton published January 29, 2009 titled "Optical coupler for in vivo
examination of
biological tissue," and PCT Pub. No. WO/2000/025112 from International
Application No.
PCT/GB1999/003563 published May 4, 2000 by Peter ROLFE, titled "OPTICAL
MONITORING", each of which is each incorporated herein by reference.
[0014] What is needed is an apparatus and method that uses NIR to detect
neural activity of
a particular type and function (e.g., by deriving a spatial pattern or image
of the neural activity,
and in some embodiments, determine a temporal and spatial pattern), determine
an intended
function for that pattern (e.g., to flex the right-hand index finger), and
generate a signal, image,
or other data for diagnostic purposes, or to control a neuroprosthesis, to
drive a neural stimulator
that regenerates a compound nerve-action potential (CNAP) signal in vivo, to
control a
computer, speech synthesizer, or other machine or function.
SUMMARY OF THE INVENTION
[0015] In some embodiments, the present invention provides a light-based
apparatus for
capturing signals indicative of neural activity. The signals are used for any
of a plurality of uses,
including use in prosthetic devices, nerve repair, stimulation of limbs
lacking nerve connections,
and the like. In some embodiments, the present invention provides a method and
apparatus for
detecting brain activity and particular thought patterns (e.g., for
controlling prosthetic devices,
stimulation of nerves to damaged limbs or organs, truth-versus-deception
detection, and the
like), wherein some embodiments perform such brain-activity detection non-
invasively and/or
from a distance (such as across a room) using person-tracking devices to
maintain the laser-light
source on the specific area of the brain of the person being monitored.
[0016] In some embodiments, the present invention detects nerve activity of an
animal (such
as activity in the brain of a human) by outputting a first light signal, which
includes a light pulse
having a first wavelength, onto a volume of animal tissue such that the first
light signal interacts
with the volume of animal tissue; detecting neural-signal activity by
measuring a second light
signal resulting from the interaction of the first light signal with the
volume of animal tissue;
transmitting an electrical signal based on the measured second light signal;
processing the
electrical signal; and outputting a response signal. In some embodiments, the
method further
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includes coupling the response signal to a prosthetic device, and processing
the coupled
response signal in the prosthetic device to control an action by the
prosthetic device. In some
embodiments, the first light signal includes a plurality of wavelengths that
are emitted
simultaneously from one or more locations. In some embodiments, the first
light signal includes
a plurality of wavelengths that are emitted at different times (i.e., in a
sequence). In some
embodiments, the first light signal includes a plurality of pulses at a first
wavelength that are
emitted at different times (i.e., in a sequence). In some embodiments, the
first light signal
includes a plurality of pulses each having one or more wavelengths of a
selected plurality of
wavelengths that are emitted at different times (i.e., in a sequence). In some
embodiments, the
outputting of the light pulse having the first wavelength is done outside a
human skull and the
volume of animal tissue includes human brain tissue inside the human skull. In
some
embodiments, the outputting of the light pulse having the first wavelength is
done at the dura of
the brain inside a human skull and the volume of animal tissue includes human
brain tissue
inside the human skull. In some embodiments, the outputting of the light pulse
having the first
wavelength is done outside a human vertebra (e.g., either non-invasively from
outside the skin,
or as an implanted device under the skin and/or muscle but outside the
vertebra) and the volume
of animal tissue includes human spinal cord tissue inside the vertebra. In
some embodiments,
the outputting of the light pulse having the first wavelength is done through
an opening formed
in a human vertebra (e.g., via a light emitter embedded in a wall of the
vertebra or via an optic
fiber that guides light from a location at some distance from the vertebra
(either from an
implanted passive light receiver implanted under the skin that receives light
from an emitter
outside the skin, or from an implanted light-emitting device under the skin
and/or muscle but
outside and at some distance from the vertebra) and the volume of animal
tissue includes human
spinal cord tissue inside the vertebra. In some embodiments, the outputting of
the light pulse
having the first wavelength is done from a light emitter embedded inside a
wall of the vertebra
and the volume of animal tissue includes human spinal cord tissue inside the
vertebra. In some
embodiments, the outputting of the light pulse having the first wavelength is
done from an
implanted light emitter and the volume of animal tissue includes human
peripheral-nerve tissue
inside the human patient. In some embodiments, the outputting of the light
pulse having the first
wavelength is done from a light emitter external to the human patient, and
after the light passes
into the patient (e.g., through the skin), this initial light is received by a
passive implanted light
receiver (e.g., a fiber-optic array affixed to a flexible substrate, which is
placed against the nerve
area of interest) and the received light (i.e., still the initial light signal
before interaction with the
tissue of interest) is conveyed to the desired location (i.e., to the tissue
of interest) within the
patient via optic fibers or a fiber bundle. In some embodiments, the volume of
animal tissue of
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interest includes human peripheral-nerve tissue and/or spinal cord tissue
and/or brain tissue
inside the human patient. There, the light interacts with the tissue of
interest, such that the
amount of light redirected to one or more detectors changes in intensity
and/or the amount of
delay (e.g., in some embodiments, this delay is detected by analysis of the
changes to phase of
the intensity modulation on the light signal). (The changes in intensity and
delay are due to
interaction of the light with the nerve tissue. It is thought that the
interaction typically includes
(1) diffusion through translucent tissue, (2) repeated scattering and/or (3)
refractions due to
changes in index of refraction coinciding with nerve firing or other time-
varying physiological
events. It is also believed changes in index of refraction cause a change in
the amount of delay
(such as can be measured by a change in phase of a high-frequency intensity
modulation
imposed on the light pulse) between the time of initial emission of the output
light pulse and the
time of detection of the interacted pulse.)
[0017] In some embodiments, the interaction of the first light signal with the
particular
nerve or brain area whose activity is being monitored causes a fluorescent
emission of light
having a second wavelength different than the first wavelength, and the
measuring of the second
light signal includes detecting light of the second wavelength.
[0018] In some embodiments, the interaction of the first light signal with the
particular
nerve or brain area whose activity is being monitored causes a change in
scattering, reflection,
birefringence or other effect on the light having the first wavelength, and
the measuring of the
second light signal includes detecting light of the first wavelength. In some
embodiments, the
first light signal is an emitted light pulse of the first wavelength and the
measuring of the second
light signal includes detecting light of the first wavelength during one or
more time periods
shortly following the emitted pulse (e.g., detecting a response waveform
(e.g., the amplitude
and/or phase delay) of light at the first wavelength) from one or more
detection locations. In
some embodiments, a mathematical transform is performed on the detected light
signal from a
plurality of sensors each located at a location (e.g., located at a point of a
Cartesian grid or array)
that permits triangulation or other location techniques to determine a
location in three-
dimensional space relative to the patient. For example, in some embodiments,
the detector
sensors are located on a grid against the scalp of the patient, and are used
to determine a
particular pattern of brain regions that are active (e.g., as a nerve signal
is processed and
propagated to different locations in the brain), wherein the pattern would
normally result in
sending the nerve signal to the limb being moved. For example, the pattern may
start as the
INTENTION for a limb movement is formed in one area of the brain (e.g., the
pre-motor cortex
or the presupplementary motor area, where neural activity may indicate
planning the movement,
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but before the movement starts) and then is propagated to another region of
the patient's brain
where the MUSCLE/MOTOR CONTROL is effected. In a patient who is missing that
limb, the
detected nerve signal can then be used to control a prosthetic limb, while in
another patient who
has nerve damage in nerves to a limb or organ, the detected nerve signal can
then be used to
control a nerve-stimulation device that causes a nerve stimulation beyond the
nerve-damage area
in order to obtain control of the limb or organ.
[0019] In some embodiments, the first light signal is an emitted light pulse
of the first
wavelength and the measuring of the second light signal includes detecting
light of a second
wavelength, which is different than the first wavelength, during one or more
time periods shortly
following the emitted pulse (e.g., detecting a response waveform of light at
the second
wavelength, e.g., a wavelength that is a fluorescent re-emission of light that
was absorbed by
some region of the nerve or surrounding tissue). In some embodiments, the
first light signal is
an emitted light pulse at each of a first plurality of wavelengths and the
measuring of the second
light signal includes detecting light at each respective one of the first
plurality of wavelengths,
which are the same respective wavelengths that were originally emitted, during
one or more time
periods shortly following the emitted pulse (e.g., detecting a response
waveform of light at the
second wavelength). In some embodiments, the detected light of the second
wavelength is
indicative of a brain activity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. IA is a block diagram of neural-signal-capture system 101
according to some
embodiments of the present invention.
[0021] FIG. IB is a block diagram of neural-signal-capture system 102
according to some
embodiments of the present invention.
[0022] FIG. 1C is a block diagram of single-laser vertical cavity surface
emitting laser
(VCSEL) source 103 according to some embodiments of the present invention.
[0023] FIG. 1D is a block diagram of one-dimensional VCSEL source linear array
104
according to some embodiments of the present invention.
[0024] FIG. IE is a block diagram of two-dimensional VCSEL source array 105
according
to some embodiments of the present invention.
[0025] FIG. IF is a block diagram of two-dimensional VCSEL source/detector
array 106
according to some embodiments of the present invention.
[0026] FIG. 1G is a block diagram of flex-cuff linear VCSEL source/detector
array 107
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according to some embodiments of the present invention.
[0027] FIG. 1H is a block diagram of neural-signal-capture system 108
according to some
embodiments of the present invention.
[0028] FIG. 2A is a block diagram of neural-signal-capture system 201
according to some
embodiments of the present invention.
[0029] FIG. 2B is a block diagram of neural-signal-capture system 202
according to some
embodiments of the present invention.
[0030] FIG. 2C is a block diagram of neural-signal-capture system 203
according to some
embodiments of the present invention.
[0031] FIG. 2D is a block diagram of neural-signal-capture system 204
according to some
embodiments of the present invention.
[0032] FIG. 2E is a block diagram of neural-signal-capture system 205
according to some
embodiments of the present invention.
[0033] FIG. 2F is a block diagram of neural-signal-capture system 206
according to some
embodiments of the present invention.
[0034] FIG. 3A is a block diagram of neural-signal-capture system 301 that
uses a square-
pulse light signal according to some embodiments of the present invention.
[0035] FIG. 3B is a block diagram of neural-signal-capture system 302 that
uses a plurality
of simultaneous intensity-modulated-pulse light signals according to some
embodiments.
[0036] FIG. 3C is a block diagram of neural-signal-capture system 303 that
uses a plurality
of sequential intensity-modulated-pulse light signals according to some
embodiments.
[0037] FIG. 3D is a block diagram of neural-signal-capture system 304 that
uses a plurality
of rigid-unit portions, each having a plurality of VCSELs and a plurality of
circumferential
detectors, that are interconnected using flex circuitry according to some
embodiments.
[0038] FIG. 3E is a plan-view block diagram of rigid unit 305 having a
plurality of VCSELs
and a plurality of circumferential detectors according to some embodiments.
[0039] FIG. 3F is a cross-section-view block diagram of VCSEL/detector 306
having one
VCSEL and a plurality of circumferential detectors according to some
embodiments.
[0040] FIG. 3G is a block diagram of neural-signal-capture system 307 that
uses one or
more intensity-modulated-pulse light signals and a plurality of detectors
according to some
embodiments of the present invention.
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DETAILED DESCRIPTION
[0041] Although the following detailed description contains many specifics for
the purpose
of illustration, a person of ordinary skill in the art will appreciate that
many variations and
alterations to the following details are within the scope of the invention.
Accordingly, the
following preferred embodiments of the invention are set forth without any
loss of generality to,
and without imposing limitations upon the claimed invention.
[0042] In the following detailed description of the preferred embodiments,
reference is made
to the accompanying drawings that form a part hereof, and in which are shown
by way of
illustration specific embodiments in which the invention may be practiced. It
is understood that
other embodiments may be utilized and structural changes may be made without
departing from
the scope of the present invention.
[0043] The leading digit(s) of reference numbers appearing in the Figures
generally
corresponds to the Figure number in which that component is first introduced,
such that the
same reference number is used throughout to refer to an identical component
that appears in a
plurality of figures. Signals and connections may be referred to by the same
reference number
or label, and the actual meaning will be clear from its use in the context of
the description.
[0044] Figure IA is a block diagram of neural-signal-capture system 101
according to some
embodiments of the present invention. In some embodiments, system 101 includes
one or more
light sources 111 (such as a VCSEL (vertical-cavity surface-emitting laser),
VCSEL array,
point-source LED (light-emitting diode) array, and the like). In some
embodiments, the light
sources 111 emit light toward tissue volume 96 (which may include overlying
tissue 97 (e.g.,
skin, muscle and/or bone) and the tissue of interest 98). The scattered or
reflected light returns
and is detected by detectors 112, which generate electrical signals that are
analyzed by signal
processor 113. The signal processor 113 outputs one or more control signals
119 (e.g., to
control a nerve stimulator 114 that optically and/or electrically stimulates
nerves 99 of the
patient, thereby possibly bypassing areas of the patient's nerve or brain
damage). In some
embodiments, the control signals are coupled to a display that displays the
spatial and temporal
patterns of neural activity. In some embodiments, the control signals are
coupled to a diagnosis
apparatus that performs an analysis (e.g., a medical diagnosis or truth-versus-
deception
detection) of the spatial and temporal patterns of neural activity. In some
embodiments, the
control signals are coupled to a prosthesis (e.g., a neuroprosthesis, robotic
arm or leg, or the like)
that performs some function for the patient.
[0045] In some embodiments, the light sources 111 emit light in the wavelength
range of
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680 nm to 850 nm (in some embodiments, wavelengths of about 830 nm are used to
improve the
signal-to-noise (S/N) ratio; however, other embodiments use one or more
different wavelengths
in the range 800 nm to 850 nm. In some embodiments, wavelengths of 680 nm, 750
nm, 830
nm, 775 nm, 845 nm, 904 nm and/or 805 nm are used. In some embodiments, very
short
substantially square pulse sources are used (outputting pulses that are
shorter than 1 nanosecond
(ns)), while in other embodiments, pulses having a duration in the range of 1
ns to 10 ns or even
to 100 ns are used. In some embodiments, the pulses are also intensity
modulated with a high-
frequency sine wave (e.g., using a modulation frequency of 1 GHz, a 10-ns
pulse will have ten
cycles of the one-GHz intensity modulation, while a 100-ns pulse will have one
hundred cycles
of the one-GHz intensity modulation. In other embodiments, the present
invention uses square
pulses having pulse durations in the range of less than about 1 picosecond
(ps) to about 1
millisecond (ms) (e.g., in some embodiments, the duration of emitted pulses is
in a range of
about 1 to 10 ps; in other embodiments, the duration of emitted pulses is in a
range of about 1 to
1000 femtosecsonds (fs), inclusive; a range of about 10 to about 100 ps,
inclusive; a range of
about 100 to about 200 ps, inclusive; a range of about 200 to about 500 ps,
inclusive; a range of
about 500 to about 1000 ps, inclusive; a range of about 1 to about 2 ns,
inclusive; a range of
about 2 to about 5 ns, inclusive; a range of about 5 to about 10 ns,
inclusive; a range of about 10
to about 20 ns, inclusive; a range of about 20 to about 50 ns, inclusive; a
range of about 50 to
about 100 ns, inclusive; a range of about 100 to about 200 ns, inclusive; a
range of about 200 to
about 500 ns, inclusive; a range of about 500 to about 1000 ns, inclusive; a
range of about 1 to
about 2 s (microseconds), inclusive; a range of about 2 to about 5 s,
inclusive; a range of
about 5 to about 10 s, inclusive; a range of about 10 to about 20 s,
inclusive; a range of about
20 to about 50 s, inclusive; a range of about 50 to about 100 s, inclusive;
a range of about 100
to about 200 s, inclusive; range of about 200 to about 500 s, inclusive;
and/or a range of
about 500 to about 1000 s, inclusive.
[0046] In some embodiments, suitably long pulses are also intensity modulated
with a
modulation frequency of between about 50 MHz or less to about 1 GHz or more.
For example,
some embodiments output one or more pulses, each modulated with a frequency
selected from
the set consisting of 10 MHz, 20 MHz, 30 MHz, 40 MHz, 50 MHz, 60 MHz, 70 MHz,
80 MHz,
90 MHz, 100 MHz, 110 MHz, 120 MHz, 130 MHz, 140 MHz, 150 MHz, 160 MHz, 170
MHz,
180 MHz, 190 MHz, 200 MHz, 210 MHz, 220 MHz, 230 MHz, 240 MHz, 250 MHz, 260
MHz,
270 MHz, 280 MHz, 290 MHz, 300 MHz, 310 MHz, 320 MHz, 330 MHz, 340 MHz, 350
MHz,
360 MHz, 370 MHz, 380 MHz, 390 MHz, 400 MHz, 410 MHz, 420 MHz, 430 MHz, 440
MHz,
450 MHz, 460 MHz, 470 MHz, 480 MHz, 490 MHz, 500 MHz, 510 MHz, 520 MHz, 530
MHz,
540 MHz, 550 MHz, 560 MHz, 570 MHz, 580 MHz, 590 MHz, 600 MHz, 610 MHz, 620
MHz,
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630 MHz, 640 MHz, 650 MHz, 660 MHz, 670 MHz, 680 MHz, 690 MHz, 700 MHz, 710
MHz,
720 MHz, 730 MHz, 740 MHz, 750 MHz, 760 MHz, 770 MHz, 780 MHz, 790 MHz, 800
MHz,
810 MHz, 820 MHz, 830 MHz, 840 MHz, 850 MHz, 860 MHz, 870 MHz, 880 MHz, 890
MHz,
900 MHz, 910 MHz, 920 MHz, 930 MHz, 940 MHz, 950 MHz, 960 MHz, 970 MHz, 980
MHz,
990 MHz, 1000 MHz, 1100 MHz, 1200 MHz, 1300 MHz, 1400 MHz, 1500 MHz, 1600 MHz,
1700 MHz, 1800 MHz, 1900 MHz, 2000 MHz, 2100 MHz, 2200 MHz, 2300 MHz, 2400
MHz,
2500 MHz, 2600 MHz, 2700 MHz, 2800 MHz, 2900 MHz, 3000 MHz, 3100 MHz, 3200
MHz,
3300 MHz, 3400 MHz, 3500 MHz, 3600 MHz, 3700 MHz, 3800 MHz, 3900 MHz, 4000
MHz,
4100 MHz, 4200 MHz, 4300 MHz, 4400 MHz, 4500 MHz, 4600 MHz, 4700 MHz, 4800
MHz,
4900 MHz, 5000 MHz. In some embodiments, modulation frequencies above 5 GHz
(e.g.,
within the range of 5 GHz to 100 GHz) are used.
[0047] Water has an index of refraction of about 1.33, while air has an index
of refraction of
about 1.0003. Light in air travels about 30 centimeters per nanosecond. Light
in water travels
about 22.6 centimeters per nanosecond, which is 0.226 millimeters (mm) per
picosecond (the
inverse being about 4.42 picoseconds per mm). If the light is reflected or
scattered substantially
directly back to a detector next to the light emitter, a resolution of about
10 picoseconds should
locate the reflecting region within about 2.26 mm for the round trip, which
should give a depth
(one-way distance) resolution of about 1.1 mm. In some preferred embodiments,
pulses having
a duration in the range of 10 ps to 20 ps are used, which may result in a
depth resolution (i.e., a
precision of location determination) of about 1 to 2 mm measuring from a
center of the emitted
pulse to the center of the reflected pulse. In some embodiments, a measurement
to a leading or
trailing edge of the pulse is used, which may provide much finer resolution,
e.g., submillimeter.
[0048] Since a compound nerve action potential (CNAP) pulse will have a
duration of about
0.25 to 0.5 milliseconds, the present invention can transmit a large number of
light pulses across
the period in which a single CNAP pulse is active at a given location. For
example, in some
embodiments, pulses are emitted every 100 nanoseconds (10 million pulses per
second), such
that 2500 to 5000 pulses can be emitted and detected during a single CNAP
pulse (with a 10-ps
pulse duration, the duty cycle of the light pulses (e.g., laser pulses) in
such a system would be
about 0.0001). In other embodiments, pulses are emitted at other intervals,
such as every 1
microsecond (1 million pulses per second), such that 250 to 500 pulses can be
emitted and
detected during a single CNAP pulse, or such as every 10 microseconds (100
thousand pulses
per second), such that 25 to 50 pulses can be emitted and detected during a
single CNAP pulse,
or even such as every 100 microseconds (10 thousand pulses per second), such
that 2 to 5 pulses
can be emitted and detected during a single CNAP pulse.
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[0049] In some embodiments, the distance to the active neural tissue (the
tissue that causes a
change in interaction with the light) is determined by starting a timing pulse
when the light is
emitted or launched toward the tissue volume of interest, and terminating the
timing pulse with
the reflected signal is detected, such that the duration of the timing pulse
is proportional to the
distance to the region that reflected the light pulse. In some embodiments,
pulse durations of 1
nanosecond, 2 nanoseconds, 5 nanoseconds or 10 nanoseconds are used, wherein
the leading
edge of the emitted pulse to the leading edge of the reflected pulse are the
triggers for the start
and end of the timing pulse, respectively. For example, if the leading (or
trailing) edge of a 5-
nanosecond emitted light pulse starts the timing pulse and the leading (or
trailing) edge of the
reflected pulse stops the timing pulse, and the anomaly that retro-reflects
the pulse (reflects the
pulse at substantially 180 degrees, straight back at the emitter) is about 10
mm deep in tissue
that has an index of refraction approximately the same as water, the timing
pulse would have a
duration of about 88.5 picoseconds ((the round-trip distance of 20 mm) times
(the speed of light
in water of 4.425 ps/mm) = 88.5 ps). If the anomaly were about 11 mm deep in
the same tissue,
the timing pulse would have a duration of about 97.3 picoseconds. Thus a
measurement of the
time-of-flight timing pulse to within about plus-or-minus 8.8 picoseconds will
yield a depth
resolution of about plus-or-minus 1 mm. Accordingly, in some embodiments, when
using
relatively long pulses (e.g., 1 to 20 nanoseconds pulse duration), it is
important to have a
relatively fast rise time (if using the leading edge of the pulse) or a
relatively fast fall time (if
using the trailing edge of the pulse) in order to accurately determine the
depth to (or three-
dimensional location of) the active neural tissue by such time-of-flight
measurements.
[0050] In some such embodiments, time-of-flight measurements are used to
detect the
distance to the particular nerve or brain area whose activity is being
monitored. For example, in
some embodiments, time-of-flight measurements measure the time between when
the pulse is
emitted (e.g., the time of this event could be measured from the start of the
pulse, when the
pulse's leading edge first reaches I/e or 1/2 of the maximum intensity, the
middle of the pulse (if
the pulse is relatively short, e.g., 5 to 10 picoseconds for a resolution of
about 1 mm) or the end
(trailing edge) of the pulse) until the corresponding feature (e.g., leading
or trailing edge) of the
pulse that is reflected or scattered due to nerve activity is detected.
[0051] In some embodiments, a tissue phantom (simulated tissue material having
one or
more reflective or scattering anomalies at known locations) is used to help
calibrate the time-of-
flight-to-distance calculation. In some such embodiments, several different
nerves at different
locations are substantially simultaneously monitored by emitting short pulses
at different times,
and different detectors 112 detecting different scattering patterns are
processed with processor
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113 using techniques similar to those used for processing x-ray CAT scans or
MRI scans. In
some embodiments, nerve stimulators 114 are used to stimulate nerves that may
have been
severed or otherwise damaged. In some embodiments, other outputs are generated
by processor
113, such as outputting diagnostics, driving neuro-modulation devices or
neuroprostheses, truth-
versus-deception detection, and the like.
[0052] In some embodiments, the source-to-detector separation is used to probe
various
depths of tissue and relates to the spatial precision of our signal capture.
For example, aiming
the emitter(s) to transmit the light pulse at a 45-degree angle to the
external skin surface and
against the skull, and spacing the detectors about 2.8 cm away, the detectors
pointing back at
about a 45-degree angle to the external skin surface, a volume of tissue about
1.4 cm deep half
way between the emitters and detectors can be monitored. Also, in some
embodiments, the
angles of orientation of both source and detector are adjusted to empirically
determine and
maximize the signal captured from the detected light.
[0053] The inventors recognize that various areas of the brain (such as the
cortex), spinal
cord, and peripheral nerves are spatially organized to a specific function.
For example, the
motor control of the foot starts in a specific area of the brain (for the
intent to move) then goes to
another area of the brain (the motor-control initiation) and then is
transmitted within a specific
nerve-bundle location within the spinal cord. In some embodiments, by placing
a cuff of
sources and detectors around the spinal cord at a suitable vertebra along the
patient's spinal
column and measuring (through reflection and/or transmission) the light
signal, some
embodiments use signal processing to get information about a very small volume
or cross
section of neural tissue - specifically, the amplitude, position, and timing
of the signal within the
spinal cord. This yields information of the functional intent of the neuron or
group of neurons
firing which can be used as a diagnostic tool or to drive a closed-loop
prosthetic device (for
example, to bypass an area of nerve damage lower in the spinal cord).
Similarly, if the nerve
damage is quite high along the spinal cord, making it difficult or impossible
to detect nerve
activity in the spinal cord, some embodiments detect brain activity in the
motor-control area for
the specific muscle movement, or even detect brain activity in the intention-
forming areas of the
brain (to detect when the patient is forming the intent for a particular
motion even before that
intent is transferred to the motor-control area) if brain activity in the
motor-control area is
damaged or for some other reason difficult or impossible to accurately
monitor.
[0054] Figure IB is a block diagram of neural-signal-capture system 102
according to some
embodiments of the present invention. In some embodiments, system 102
transmits the light
pulses from light source 111 through overlying tissue such as skin 91, skull
bone 92, and dura 93
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in order to illuminate excitable neuronal tissue 94 (such as the brain, spinal
cord, spinal roots,
peripheral nerves and/or sensory nerves) non-invasively. In other embodiments,
an implanted
device is used, wherein the system 102 is configured to be implanted within
the patient to
perform the nerve-activity measurement and the resulting control function. In
some
embodiments, detectors 112 are arrayed around a room and surreptitiously used
to monitor a
subject person 89. The use of infra-red illumination light sources 111 such as
VCSEL lasers
prevents the subject person 89 from knowing she or he is being monitored.
[0055] Figure 1C is a block diagram of single-laser vertical cavity surface
emitting laser
(VCSEL) source 103 according to some embodiments of the present invention.
Source 103 can
be a semiconductor VCSEL, but in other embodiments, point-source diodes, LEDs,
diode-laser-
pumped fiber-based lasers (wherein one or more rare-earth species are used as
a dopant in the
optical fiber, wavelength-converted (e.g., a frequency-doubled erbium laser,
wherein the erbium
laser emits at about 1550 nm (which does not penetrate human tissue to any
great extent) and
this light is frequency-doubled to about 775 nm (which will penetrate human
tissue fairly
well))), or other lasers are used.
[0056] Figure 1D is a block diagram of one-dimensional VCSEL source linear
array 104
according to some embodiments of the present invention. In some embodiments,
array 104
consists of an integrated linear array of VCSELs.
[0057] FIG. lE is a block diagram of two-dimensional VCSEL source array 105
according
to some embodiments of the present invention. In some embodiments, array 105
includes laser
sources with one specific wavelength. In other embodiments, array 105 includes
laser sources
having a plurality of different wavelengths. In some embodiments, a single
pulse duration and a
single pulse-repetition-rate (PRR) frequency are used, while in other
embodiments, a plurality of
different pulse durations and/or PRR frequencies are used. In some
embodiments, array 105
consists of an integrated two-dimensional array of VCSELs.
[0058] FIG. IF is a block diagram of two-dimensional VCSEL source/detector
array 106
according to some embodiments of the present invention. In some embodiments, a
plurality of
different detector types is used, wherein each type is configured to be
sensitive to different
wavelengths. In some embodiments, a plurality of otherwise substantially
similar detectors are
coated with wavelength-selective filter coatings or Fabry-Perot
interferometers (e.g., either all
tuned to one specific wavelength or, in other embodiments, tuned to a
plurality of different
wavelengths) to only accept one or more specific wavelengths - thus boosting
signal-to-noise
ratios. In some embodiments, system 106 is substantially similar to array 105,
with the
exception that some of the sources have been replaced by detectors. In some
embodiments, a
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VCSEL-type device can be used as a detector by appropriate changes to the
biasing circuitry.
[0059] FIG. 1G is a block diagram of flex-cuff linear VCSEL source/detector
array 107
according to some embodiments of the present invention.
[0060] FIG. 1H is a block diagram of neural signal capture system 108
according to some
embodiments of the present invention. In some embodiments, system 108 is
substantially
similar to system 102 of Figure 1B, with the exception that an opening in the
skull has been
created to obtain finer resolution in the sensing of different nerve areas.
[0061] FIG. 2A is a block diagram of neural-signal-capture system 201
according to some
embodiments of the present invention. In some embodiments, system 201 is used
to detect
specific nerves in a nerve bundle of spinal cord 95. In other embodiments,
system 201 is used to
detect specific neural activity in nerves in a nerve bundle of peripheral
nerves. In some
embodiments, detectors 112 and light source 111 are arranged in a flexible
cuff surrounding
some or all of spinal cord 95, in order to detect nerve signals on one side of
a break in the spinal
cord and to create stimulation signals from device 114 to a portion of the
spinal cord 95 on the
opposite side of the break. In some embodiments, system 201 includes a series
of devices that
sense nerve signals going the opposite direction and recreating stimulation
back on the original
side of the break.
[0062] FIG. 2B is a block diagram of neural-signal-capture system 202
according to some
embodiments of the present invention. In some embodiments, system 202 includes
a non-
invasive cap holding light sources 111, detectors 112, and processors 113. In
some
embodiments, system 202 is used to detect neural activity in one or more
specific brain areas of
a cerebral cortex or other brain area of brain 94. In other embodiments,
system 202 is used to
detect specific nerves in one or more other brain areas. In some embodiments,
detectors 112 and
source(s) 111 are arranged in a non-invasive opaque cap 222 (which, in some
embodiments,
holds one or more very-short-pulse VCSEL sources 111, detectors 112, and
signal processors
113), which, when operating, surrounds some or all of the head of person 89,
in order to detect
neural activity in an area of the brain (e.g., in a case where the person 89
has some brain damage
or damage in the spinal cord such that she or he can no longer control some
motor or speech
function). System 202 creates stimulation signals from nerve-stimulation
device 114 to nerves
99 (e.g., in the case shown here, one or more efferent nerves of a limb or
organ lacking effective
connections to the brain) in a portion of the spinal cord 95 or peripheral
nervous system closer to
the muscles or organ to be controlled. In some embodiments, system 202 also
includes one or
more devices that sense nerve signals going the opposite direction and
recreating brain-detected
sensations in a certain area of the brain 94 using nerve stimulation of either
nerves in the spinal
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cord or brain.
[0063] FIG. 2C is a block diagram of neural-signal-capture system 203
according to some
embodiments of the present invention. In some embodiments, system 203 includes
an implanted
device 232 (which, in some embodiments, holds light sources (e.g., VCSEL
arrays) 111,
detectors 112, and signal processors 113) that has been embedded in the skull
bone 92. In some
embodiments, other aspects of system 203 are as described above for Figure 2A.
In some
embodiments, system 203 has the advantages of being more stable (less movement
relative to
the brain), while being less invasive than system 204 described below. System
203 also has the
advantages of having less tissue to go through (relative to system 202
described above) to reach
the areas of the brain that are being monitored.
[0064] FIG. 2D is a block diagram of neural-signal-capture system 204
according to some
embodiments of the present invention. In some embodiments, system 204 includes
an implanted
device 242 (holding light sources 111, detectors 112, and processors 113) that
has been
implanted between the skull bone 92 and the brain 94. In some embodiments,
other aspects of
system 203 are as described above for Figure 2A. In some embodiments, system
204 has the
advantages of being perhaps even more stable (less movement relative to the
brain), although
being more invasive than systems 202 and 203 described above. System 204 also
has the
advantages of having much less tissue to go through (relative to system 202 or
system 203
described above) to reach the areas of the brain that are being monitored.
[0065] FIG. 2E is a block diagram of neural-signal-capture system 205
according to some
embodiments of the present invention. In some embodiments, system 205 is
substantially
similar to system 204 of Figure 2D with the exception that, in some
embodiments, the detected
brain patterns are further analyzed in device 214 and used to drive actuator
drives 87 that drive
movement in appendages (e.g., fingers 86) and other functions of prosthetic
device 88 for person
89. Implanted device 252 is otherwise similar to device 242 described for
Figure 2D above.
[0066] FIG. 2F is a block diagram of neural-signal-capture system 206
according to some
embodiments of the present invention. In some embodiments, system 206 is used
in the
opposite direction of previous conventional devices, such as those described
in the related patent
applications and patents listed at the beginning of this application, in that
sensory nerve signals
are provided and stimulation signals conveying the sensory device are sent to
the brain 94. For
example, in some embodiments, the light sources 111 emit light toward tissue
volume 96
(which, as described above in Figure IA, may include overlying tissue 97
(e.g., skin, muscle
and/or bone) and the tissue of interest 98 (in this case, an afferent nerve
bundle)). The scattered
or reflected light returns or is transmitted generally through the tissue
volume 96 and is detected
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by detectors 112, which generate electrical signals that are analyzed by
signal processor 113.
The signal processor 113 outputs one or more control signals (e.g., to control
a nerve stimulator
114 that optically and/or electrically stimulates brain 94 of the person 89,
thereby, if the person
is affected by such problems, bypassing areas of the patient's nerve damage or
brain damage)
based on the actual senses of person 89 whose afferent nerves (within tissue
96) are monitored.
[0067] FIG. 3A is a block diagram of neural-signal-capture system 301 that
uses a square-
pulse light signal (e.g., a pulse that is not modulated with a higher-
frequency sine wave such as
are described in Figure 3B and Figure 3C) according to some embodiments of the
present
invention. In some embodiments, system 301 provides an electrical signal
having the square-
pulse shape as shown (amplitude in the vertical direction versus time in the
horizontal direction),
and applies the electrical pulse to one or more VCSEL sources 311 (which
generate a light pulse
having a light intensity or power corresponding to the applied electrical
pulse). In some
embodiments, system 301 includes one or more light sources 311 (such as a
VCSEL (vertical-
cavity surface-emitting laser), VCSEL array, point-source LED (light-emitting
diode) array, and
the like). In some embodiments, the light sources 311 emit light toward tissue
volume 96
(which, as shown in Figure IA, may include overlying tissue 97 (e.g., skin,
muscle and/or bone)
and the tissue of interest 98). The scattered transmitted or reflected light
returns and is detected
by detectors 312, which generate electrical signals that are analyzed by
signal processor 313.
The signal processor 313 outputs one or more control signals which are used as
described above
for Figure IA. In other embodiments, pulse shapes other than square are used,
e.g., triangular,
saw-tooth (i.e., having either a fast rise time or a fast fall time), ramped
up or down, or other
suitable shapes.
[0068] FIG. 3B is a block diagram of neural-signal-capture system 302 that
uses a plurality
of simultaneous intensity-modulated-pulse light signals according to some
embodiments of the
present invention. In some embodiments, system 302 provides a plurality of
electrical signals
having the simultaneous intensity-modulated square-pulse shape as shown
(amplitude in the
vertical direction versus time in the horizontal direction), and applies the
electrical pulse to one
or more VCSEL sources 321 (which each generate a light pulse having a light
intensity or power
corresponding to the respective applied electrical pulse). In some
embodiments, system 302
includes a plurality of light sources 321 (such as a VCSEL (vertical-cavity
surface-emitting
laser), VCSEL array, point-source LED (light-emitting diode) array, and the
like). In some
embodiments, the light sources 321 emit light toward tissue volume 96. The
scattered
transmitted or reflected light returns and is detected by detectors 322 that
in some embodiments,
include a plurality of intensity-frequency filters 324 (i.e., bandpass filters
that pass only signals
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within the intensity-modulation frequencies used in the modulation of the
original light pulse),
each of which generate electrical signals that are analyzed by signal
processor 323. In some
embodiments, each one of a plurality of the intensity-modulated square-pulses
has an overall
envelope with a square (constant-intensity) shape that is modulated with a
plurality of cycles of
a higher-frequency modulation frequency. (In other embodiments, pulse
envelopes other than
square are used, e.g., triangular, saw-tooth, ramped up or down, or other
suitable shapes.) In the
embodiment shown, a 10-ns pulse is modulated with seven cycles of a 700 MHz
cosine wave for
the uppermost signal shown, a 10-ns pulse is modulated with eight cycles of a
800 MHz cosine
wave for the upper-middle signal shown, a 10-ns pulse is modulated with nine
cycles of a 900
MHz cosine wave for the lower-middle signal shown, or a 10-ns pulse is
modulated with ten
cycles of a 1000 MHz cosine wave for the lowermost signal shown. In some
embodiments, each
of the different-modulated-frequency pulses is emitted simultaneously, wherein
each detector is
followed by a plurality of parallel-wired frequency filters (e.g., one filter
having a relatively
narrow bandpass at 700 MHz, another filter having a relatively narrow bandpass
at 800 MHz,
another filter having a relatively narrow bandpass at 900 MHz, and another
filter having a
relatively narrow bandpass at 1000 MHz). In some embodiments, the different
intensity-
modulation-frequency pulses are each launched from a different VCSEL at spaced-
apart
locations. Thus, each of the filters is outputting a signal that came from
only one of the VCSEL
locations, allowing simultaneous triangulation to the neural activities being
monitored. In some
embodiments, the simultaneous emission of pulses having a plurality of
different intensity-
modulation frequencies, along with detectors each having a corresponding set
of bandpass filters
at the different intensity-modulation frequencies, allows faster repetition of
the pulses (a higher
pulse-repetition rate (PRR)) and thus greater data acquisition at the cost of
the additional
filtering circuits 324 and/or signal-processing circuits 323. In some
embodiments, device 302
outputs a series of such parallel-in-time intensity-modulated sets of light
pulses one after
another, with the time gap between pulses being relatively short (e.g., as
short as 10 ns or less in
embodiments similar to the embodiment shown (which shows only a single set of
substantially
parallel-in-time (simultaneous) pulses), such that the PRR can be as high as
50 million pulses
per second (MPPS) (with 10-ns pulses separated in time by 10-ns gaps) or more.
In some
embodiments, each of a plurality of VCSEL sources can each emit at a different
wavelength
(e.g., 680 nm, 750 nm and 830 nm) and each of a plurality of detectors
includes a wavelength
bandpass filter tuned to a corresponding different wavelength (e.g., 680 nm,
750 nm and 830
nm), such that simultaneous pulses at different light wavelengths from the
plurality of different
emitters can be each detected by a different detector, further increasing the
data-capture
capability. The signal processor 323 outputs one or more control signals, used
as described
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above for Figure IA.
[0069] FIG. 3C is a block diagram of neural-signal-capture system 303 that
uses a plurality
of sequential intensity-modulated-pulse light signals according to some
embodiments of the
present invention. In some embodiments, system 303 provides a plurality of
electrical signals
having the sequentially-launched intensity-modulated square-pulse shape as
shown (amplitude
in the vertical direction versus time in the horizontal direction), and
applies the electrical pulse
to one or more VCSEL sources 331 (which generate a light pulse having a light
intensity or
power corresponding to the applied electrical pulse). In some embodiments,
system 303
includes a plurality of more light sources 331 (such as a VCSEL (vertical-
cavity surface-
emitting laser), VCSEL array, point-source LED (light-emitting diode) array,
and the like). In
some embodiments, the light sources 331 emit light toward tissue volume 96.
The scattered
transmitted or reflected light returns and is detected by detectors 332, each
of which generates
electrical signals that are analyzed by signal processor 333. In some
embodiments, each one of a
plurality of the intensity-modulated square-pulses has an overall envelope
with a square
(constant-intensity) shape that is modulated with a plurality of cycles of a
higher-frequency
modulation frequency. In some embodiments, each pulse is modulated with the
same frequency,
while in other embodiments, each pulse is intensity modulated using a
different frequency (for
example, in the embodiment shown, modulated with seven cycles of a 700 MHz
cosine wave,
with eight cycles of a 800 MHz cosine wave, with nine cycles of a 900 MHz
cosine wave for the
lower-middle signal shown, or with ten cycles of a 1000 MHz cosine wave). In
some
embodiments, each of the different-modulated-frequency pulses is emitted
sequentially, wherein
each detector is followed by one or more frequency filters. In some
embodiments, the different
intensity-modulation pulses are each launched from a different VCSEL at spaced-
apart
locations. In some embodiments, the sequential emission of pulses having a
single intensity
modulation frequency, along with detectors each having a corresponding single
bandpass filter
at the given intensity-modulation frequencies, allows a lower-cost, simpler
system (for a given
pulse-repetition rate (PRR)) without the cost of the additional filtering
circuits (such as 324 of
Figure 3B) and/or signal-processing circuits 333. In some embodiments, system
303 includes a
plurality of light sources 331 (such as a VCSEL (vertical-cavity surface-
emitting laser), VCSEL
array, point-source LED (light-emitting diode) array, and the like). In some
embodiments, the
light sources 331 emit light toward tissue volume 96. The scattered
transmitted or reflected light
returns and is detected by detectors 332, each of which generates electrical
signals that are
analyzed by signal processor 333. The signal processor 333 outputs one or more
control signals
which are used as described above for Figure IA.
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[0070] FIG. 3D is a block diagram of neural-signal-capture system 304 that
uses a plurality
of rigid-unit portions 305, each having a plurality of VCSELs and a plurality
of circumferential
detectors, that are interconnected using flex circuitry 342 according to some
embodiments of the
present invention. In some embodiments, the rigid-unit portions 305 each
include a plurality of
VCSELs (e.g., three in the embodiment shown, however a fewer or greater number
of such light
emitters are used in other embodiments), each arranged in the center of two
rows of
circumferentially arranged detectors. In some embodiments, neural-signal-
capture system 304 is
formed into a skull-surrounding cap that is placed against the scalp of the
patient (person 89)
and used to capture and determine the locations of neural activity in a
plurality of areas of
interest.
[0071] FIG. 3E is a plan-view block diagram of rigid unit 305 having a
plurality of VCSELs
and a plurality of circumferential detectors (detectors 363 arranged around a
circumference)
according to some embodiments of the present invention. In some embodiments,
each such
rigid unit 305 includes a plurality of VCSELs (e.g., three in the embodiment
shown, however a
fewer or greater number of such light emitters are used in other embodiments),
each arranged in
the center of one or more rows of circumferentially arranged detectors (e.g.,
two rows of four
detectors each in the embodiment shown, however a fewer or greater number of
such rows
and/or detectors per row are used in other embodiments). In some embodiments,
rigid unit 305
is fabricated as a single integrated circuit chip, while in other embodiments,
a hybrid module is
formed from a plurality of component chips. In some embodiments,
VCSEL/detector portion
306 is configured to emit and detect light of a first wavelength (e.g., 680
nm), while
VCSEL/detector portion 306' is configured to emit and detect light of a second
wavelength (e.g.,
750 nm), and VCSEL/detector portion 306" is configured to emit and detect
light of a third
wavelength (e.g., 830 nm). In other embodiments, other wavelengths are used.
In some
embodiments, a VCSEL control electronics and power-driver circuit 351 drives
the one or more
VCSEL/detector portions 306, 306', and/or 306". In some embodiments, the
plurality of
detectors in each of the plurality of rows allows detection of scattered light
in each of a plurality
of directions, and the plurality of rows allows detection of scattered light
at different radii. In
some embodiments, an array having a much larger number of light emitters and
detectors (e.g.,
arrays of 8-by-8, or 64-by-64, or other grid sizes of such sets of
VCSEL/detector portions 306,
306', and 306" are used, or similar grids of VCSEL/detector portions 306,
306', or 306" all of a
single wavelength).
[0072] FIG. 3F is a cross-section-view block diagram of VCSEL/detector 306
having one
VCSEL and a plurality of circumferential detectors (only one of which is shown
here) according
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to some embodiments of the present invention. In some embodiments, a plurality
of electrical
contacts 361 (only one is shown here to simplify the drawing) provide
electrical connections to
the detector 363 and VCSEL active layer 365, a bottom-side (relative to this
drawing) very-high-
reflectivity mirror 366 and a top-side (relative to this drawing) partially
transmissive and high-
reflectivity mirror 364 provide laser feedback to active layer 365. In some
embodiments, a
suitable substrate material such as GaAs, GaN, sapphire or the like is used
upon which to
fabricate the other portions. In some embodiments, a focusing reflector and/or
lens element 368
is used to output the light signal 369. In some embodiments, a wavelength-
bandpass filter 362
limits the range of wavelengths that reach detector 363, in order to reduce
background light
(noise) detection and improve the signal/noise (S/N) ratio. In some
embodiments, each detector
363 is sensitive for high-frequency (e.g., 50 MHz to 1 GHz or higher
frequencies) bandwidth
intensity-modulated light signals. That is, the wavelength bandwidth of filter
362 is narrow
(e.g., wavelengths centered on the emission wavelength plus-or-minus 10 nm or
less (or
narrower in some embodiments, e.g., plus-or-minus 5 nm, or plus-or-minus 2 nm
or plus-or-
minus 1 nm)), while the frequency bandwidth of the detector is high (e.g., 50
MHz to 1 GHz or
more (broader)).
[0073] FIG. 3G is a block diagram of neural-signal-capture system 307 that
uses one or
more intensity-modulated-pulse light signals and a plurality of detectors
according to some
embodiments of the present invention. In some embodiments, system 307 provides
a
modulation source that outputs a plurality of electrical signals having the
simultaneous (or
sequential) intensity-modulated square-pulse shape as shown in Figures 3B (or
Figure 3C) above
(which illustrate amplitude in the vertical direction versus time in the
horizontal direction), and
applies the electrical pulse to one or more VCSEL sources 371 (which each
generate a light
pulse having a light intensity or power corresponding to the respective
applied electrical pulse).
In some embodiments, system 307 includes a plurality of light sources 371
(such as a VCSEL
(vertical-cavity surface-emitting laser), VCSEL array, point-source LED (light-
emitting diode)
array, and the like). In some embodiments, the light sources 371 emit light
toward tissue
volume 96. The scattered transmitted or reflected light returns and is
detected by detectors 372
that in some embodiments, each of which generate electrical signals that are
analyzed by signal
processor 373.
[0074] In some embodiments, the present invention, using the various
strategies for neural
detection, uses component optical devices and electronic and/or software
signal-processing
technology that are assembled to form systems of the present invention. In
some embodiments,
the optical components include: an optical source having micro LED's (single
channels or
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arrays), VCSELs (vertical-cavity surface-emitting laser arrays) (single
channels or arrays) diode-
driven solid-state lasers (SSLs) and/or other small, light-emitting
substrates. Some
embodiments include optical fibers coupled to the light emitter on one end and
placed against or
near the tissue of interest at the other end for light delivery. In some
embodiments, the detector
includes one or more small detectors that are matched to the wavelength and
power
characteristics of the expected or predicted signal when light from the
optical source is applied
to tissue or region of interest. In some embodiments, the source and detector
are matched to one
another for each channel, while in other embodiments, a single source is used
in a configuration
with numerous detector elements. Some embodiments use one or more optical
fibers or other
optical elements (such as lenses and the like) for light collection.
[0075] In some embodiments, the tissue of interest includes neural tissues. In
some
embodiments, the detected signal indicates the fluid or ion pressure and/or
level of activity in a
given region. The detected and/or recorded response is converted to meaningful
data showing
the intended body function. In some embodiments, this data is output as a
signal whose
intended use is to be sent as space-and-time-sensitive signals to drive the
nerve stimulator within
the prosthetic device.
[0076] When the tissue of interest is the human brain, some embodiments use
devices for
signal capture of neural activity in the brain, wherein these devices include:
VCSEL or micro-
LED array (if one source-detector for each functional channel) that is placed
on the brain/cortex
or the dura or the skull or the skin. The source will pulse or continuously
apply light and the
detector will sample at a defined rate. Information on the power density of
the source and the
light intensity collected at the detector and the morphology/geometry of the
target tissue can be
used to monitor neural activity in a spatially and temporally selective
manner.
[0077] Movement of the brain relative to the emitter-detector probe depends on
the location
of the probe (whether the probe is inside the skull on the dura (which
achieves greater stability
and less movement), or outside the skull and/or scalp (which has more
movement, but is less
invasive and provides other advantages). Accordingly, some embodiments that
use probes
outside the scalp include remapping software that lets the user remap which
emitters and/or
detectors are used to detect particular neural patterns.
[0078] In some embodiments, the source includes a single array, a two-
dimensional array
(either in a flat (i.e., single plane, or a plurality of planes connected to
one another using flexible
(flex) circuitry), or along a curved surface such as entirely using a flex
circuit), and/or a three-
dimensional array (e.g., using a plurality of flex circuits) of light emitters
such as VCSELs or
light-emitting diodes (LEDs). In some embodiments, each channel includes a
single detector,
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while in other embodiments, each channel includes a plurality of detectors.
[0079] In some embodiments, source-detector size and geometry is optimized to
maximum
light intensity collection (i.e., strong signal capture). Source or detector
may have beam-shaping
optics to only collect signals of a certain depth. The timing of on-off of a
single source or
channel can be used to locate the recorded response from a plurality of
detectors (i.e., to provide
higher contrast and higher resolution).
[0080] In some embodiments, the source/detector signal-capture system is
passively placed
over the tissue region of interest and embedded into the skull for stability.
The system of the
present invention can transmit through some bone or bone and skin. In some
embodiments,
portions or all of the system may be placed below the dura.
[0081] Nerve-potential detection and location-determining devices of the
present invention
for signal capture of neural activity in nerve or spinal cord, in some
embodiments, include a cuff
surrounding the spinal cord or a nerve or nerve bundle with source-detector
pairs separated by
180 degrees, such that information regarding the signal (neural activity) is
contained in the
transmissive characteristics of the light from the source to the detector. By
using many source-
detector sets simultaneously, the position in three-dimensional (3-D) space of
a given signal can
be extrapolated by signal processing and sent to the prosthesis device.
[0082] Some embodiments include a cuff surrounding tissue with source-detector
pairs
adjacent to each other such that signal is contained within the reflective
characteristics of the
light. Position and beam-shaping optics will control depth of tissue probed
(in addition to laser
parameters used, like wavelength).
[0083] In some embodiments, these have a cylindrical geometry, such that a
plurality of
depths can be analyzed with the device fixed at a given tissue-surface
position. The device may
be positioned along any portion of the nervous system for signal capture.
[0084] The use of optical spectroscopy for detecting and determining the
locations and time
periods (the spatial and temporal characteristics) of neural activity provides
unprecedented
resolution (generally 10 to 50 times better than current techniques), is less
sensitive to motion,
and is very fast. Optical spectroscopy is also damage-free because the process
is less invasive
(outside the dura or skull), and the intensity is well below Food and Drug
Administration (FDA)
standards (the average power is less than 1 milliwatt (mW) through the skull).
The penetration
depth for optical spectroscopy is generally greater than 1 centimeter (cm) in
the cortex and
nerves.
[0085] Near-infrared spectroscopy (NIRS) is a specific type of spectroscopy
used to detect
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neural activity. LAIRS detects action potentials through fast-scattering
changes in real time and is
effective for a variety of wavelengths (this provides a plurality of source
options). LAIRS can run
in a continuous wave (DC) or pulsed (AC modulation) mode and the latency is
generally in the
tens of milliseconds. The wavelength operation for LAIRS generally varies from
690 nanometers
(nm) to 830 nm, or in some embodiments, up to about 904 or 1200 nm, but the
longer
wavelengths are preferred because at shorter wavelengths (e.g., 690 nm),
scattering is decreased
and hemoglobin absorption is increased (thereby decreasing the signal-to-noise
ratio), whereas at
longer wavelengths (e.g., 830 nm), scattering is increased and hemoglobin
absorption is
decreased (thereby increasing signal-to-noise ratio). In some embodiments, the
use of a plurality
of detectors each detecting one of a plurality of different wavelengths in
LAIRS improves signal-
to-noise ratio and contrast.
[0086] In some embodiments, the present invention provides an apparatus that
performs
time-resolved LAIRS to measure neural activity. In some embodiments, this time-
domain
spectroscopy uses an optical pulse source (that emits pulses that have a
duration of about 100
picosecond (ps)), since, in some embodiments, little background subtraction is
required with
such a short pulse (which provides increased signal-to-noise (T S/N) ratio).
Some embodiments
further include a detector unit that measures light intensity and "time of
flight" from a plurality
of detector sensors that are analyzed by a signal processor via a time point
spread function.
Some embodiments further include a plurality of detectors to reduce the
influence of noise due
to, e.g., superficial layers of tissue, and changes in tissue (i.e., the
interfaces between tissue types
having differing indices of refraction cause reflections, some of which, in
some embodiments,
are noise relative to the signal that is desired to be detected).
[0087] Some embodiments use optical-electrodes (optrodes) which conduct light
signals and
electrical signals to and/or from the tissue of interest (e.g., using an
optical signal to stimulate a
CNAP and detecting the resulting CNAP with the electrode, or vice versa). Some
embodiments
use an interface gel or other light-coupling enhancement between the light
emitters and the
patient's skin. Some embodiments use spatially resolved spectroscopy to reduce
or cancel
extraneous light noise.
[0088] In some embodiments, the present invention provides a method that
includes
calculating tissue optical properties using a diffusion-approximation
analysis, either for
calibration or for signal extraction.
[0089] Some embodiments detect a change in scattering to determine the
intensity of a
neural response (i.e., wherein higher-intensity neural activity (more neurons
firing within a
given period of time) indicate a higher intended force of muscle contraction),
such that the force
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applied by the prosthetic device is based on the detected intensity of neural
activity.
[0090] Some embodiments use time-of-flight determination and the source-
detector
separation to determine the exact location of neural activity (i.e., using an
empirically calibrated
brain activity map to determine which muscle the patient intended to move, and
to thus control a
prosthesis to effect that movement).
[0091] The present invention provides much quantitative information in a rapid
manner and
with high DR or data rate. The devices are highly sensitive and provide deep
penetration.
[0092] On the other hand, in some embodiments, the instrumentation is large
and when
considered as a whole is commercially unavailable, and thus is developed using
off-the-shelf
components and parts. These are then changed to a commercially viable form
suitable for
economies-of-scale improvements to reduce cost. Also, some embodiments include
a slow
hemodynamic response present in signal.
[0093] Some embodiments use a phase-modulated NIRS to measure neural activity.
In
some such embodiments, the methodology used includes frequency-domain
spectroscopy using
Fourier-type frequency analysis. In some such embodiments, the emitted light
signal pulse has
been intensity modulated at 50 MHz to 1 GHz and has an optical power on the
order of tens to
100 microwatts ( W). In some embodiments, the short pulse requires little
background
subtraction, resulting in increased signal/noise ratio (T S/N). In some
embodiments, the detected
light signal is measured in a manner that determines mean light intensity
(e.g., measured as a DC
amplitude), amplitude (e.g., measured as an AC amplitude), and phase of wave
from each one of
a plurality of detectors. In some embodiments, the time-of-flight is
determined from the phase
measurement. In some embodiments, a sequence of pulses each is modulated using
a different
frequency, wherein this scan through a plurality of frequencies allows
adequate detection using
fewer detectors (J, #D's), while a single frequency can be used for the
intensity-modulation
frequency if the device is operated in spatially resolved spectroscopy (SRS)
mode.
[0094] Some embodiments of the present invention use a plurality of detectors
(a plurality
of D's using a plurality of intensity-modulation frequencies and/or
wavelengths) such that noise
influence of various tissue features (e.g., superficial layers, changes in
tissue, placement of
optrodes, light coupling) is cancelled out.
[0095] Some embodiments simulate or calculate tissue optical properties with
diffusion-
approximation analysis, in order to calibrate the device relative to depth and
spot location. For
example, for each optical source, a calibration procedure determines which
sensors are giving
what signal in response to the patient desiring a particular movement or other
activity.
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[0096] In some embodiments, the DC signal is captured (in some embodiments,
this is
typically relatively large), and subtracted from the signal to eliminate noise
(which significantly
enhances the S/N ratio).
[0097] In some embodiments, the AC amplitude is captured and used to estimate
the
intensity of neural activity and this in turn controls a corresponding
response (i.e., intended force
of muscle contraction drives a corresponding prosthesis movement or motor-
nerve stimulation
closer to the patient's muscle to be controlled).
[0098] In some embodiments, the phase change in the detected signal is
detected, and used
with the given distance value (indicating source-detector separation) to
determine the exact
location of neural activity (e.g., a location on the brain, which location is
mapped to three-space
and used to determine which muscle the patient intended to move).
[0099] In some embodiments, the advantages of this technique include that it
is technically
relatively simple, there is rapid signal capture with a high S/N ratio. It is
highly sensitive and
has deep penetration. On the other hand, the instrumentation is relatively
large; it uses relatively
costly lasers and detectors, and complex signal processing.
[00100] In some embodiments, the present invention provides an apparatus that
includes
optical cellular arrays (e.g., a VCSEL array vertical-cavity surface-emitting
laser array).
These have sources as small as 50 m (microns), the pulses can have a duration
(pulse width) as
short as 100 ps (or shorter), or longer pulses with durations through
continuous wave (CW)
(wherein CW can have light emitted as long as power is applied). In some
embodiments, the
power is greater than 1 milliwatt (mW) per channel in NIR wavelengths. In some
embodiments,
a plurality of wavelengths is used (resulting in increased speed and increased
signal/noise ratio).
[00101] In some embodiments, the present invention provides a device for
reliable, precise
signal capture, which generates one or more signals to drive a neuroprosthetic
device.
[00102] Some embodiments develop a plurality of individual "channels" each
having one or
more sources, a plurality of detectors, and control electronics. Some
embodiments empirically
optimize source-detector (S-D) separation and geometry to increase contrast
and the quality of
the signal. In some embodiments, the present invention uses small NIR VCSELs
with improved
efficiency to reduce the electrical power consumption for implanted devices,
as well as using
highly sensitive, miniaturized detectors, and empirically optimized pulse
characteristics (such as
pulse duration, frequency of the intensity modulation, and wavelength(s)).
[00103] Some embodiments use a VCSEL array having a plurality of channels,
wherein the
channels are clustered with a plurality of channels per functional neural
group (e.g., using a
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plurality of channels to distinguish intended movement of the index finger
versus the middle
finger). Some embodiments empirically optimize "channel" separation by
changing the position
of the source-detector unit, or by changing the mapping selections of the
emitter and sensors
while leaving the source-detector unit in the same one physical location, such
that the light
emission and detection pattern is modified (e.g., under software control)
without moving the
device.
[00104] In some embodiments, the present invention provides an apparatus that
includes
integrated, miniaturized electronics to reduce overall device size and to
reduce power
consumption.
[00105] In some embodiments, the present invention provides software using
statistical-
analysis algorithms and supporting software, which are run on suitable
hardware (e.g.,
embedded high-speed, compact signal processors with high-reliability operating
systems). The
statistical-analysis algorithms output one or more signals based on the
analysis of the detected
signal's DC, AC and phase, as well as detector position, to determine location
of neural activity.
Some embodiments further include eliciting, receiving and using other user
input as to the
degree of bodily function desired. The resulting output signal(s) of the
present invention
provide high-sensitivity, high-specificity control to the interface with
neuroprostheses.
[00106] In some embodiments, the present invention co-registers the placement
of the
implanted device with functional magnetic-resonance imaging (fMRI) during
performance of
functional tasks by the patient. Once implanted, the detected response is
correlated with the
degree and location of functional movement desired by the patient. The device
is then calibrated
using this information (which may change due to movement of the device) or a
determination
that other brain patterns can be better utilized to achieve the desired
function can be used to
remap the detection criteria for a particular desired output. In some
embodiments, position
accuracy is optimized using task-based analysis (having the patient attempt to
perform various
tasks, analyzing the signals that are captured), and then adjusting the signal
processing to output
the control signal that specifies that the prosthesis performs the function
corresponding to the
patient's intention. Other embodiments omit the fMRI and simply use the
patient's expressed
description of what was intended to map a particular detection pattern to a
particular intended
result.
[00107] In some embodiments, a muscle contraction is correlated to a detected
and/or
recorded nerve-activity-detection signal using statistical analysis, which
provides high
sensitivity and specificity.
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[00108] An Appendix C is attached at the end of U. S. Provisional Patent
Application
61/081,732 (Attorney Docket 5032.044PV1) filed on July 17, 2008, titled
"METHOD AND
APPARATUS FOR NEURAL SIGNAL CAPTURE TO DRIVE NEUROPROSTHESES OR
BODILY FUNCTION," which is incorporated herein by reference in its entirety.
That
Appendix C contains additional information on the methods and apparatus for
neural-signal
capture to drive neuroprosthesis.
[00109] In some embodiments, the present invention provides an apparatus that
includes at
least one light source, the at least one light source configured to output a
light pulse having a
wavelength onto a volume of human tissue; at least one light detector
configured to receive light
reflected and transmitted by the volume of human tissue and to transmit an
electrical signal,
wherein the light reflected and transmitted by the volume of human tissue
provides an indication
of neural activity; a signal-processing unit operatively coupled to the at
least one light detector
and configured to receive the electrical signal from the at least one light
detector. Some
embodiments further include a stimulator unit operatively coupled to the
signal-processing unit
and configured to output a response signal to a prosthetic device. Some
embodiments further
include the prosthetic device.
[00110] This signal-processing unit correlates the electrical signal from the
detector detecting
of light to a particular location within the patient to quantify the neural
signal (temporal
characteristics, location (therefore function), and amplitude of the response
(how many neurons
are firing)). Also, in some embodiments, a portion of the signal processing
removes motion
artifacts due to the movement of the tissue volume of interest (e.g., the
brain sloshing around in
the skull cavity while the device is fixed to the skull will change the
boundary conditions for the
interpretation of the response).
[00111] In some embodiments, the present invention detects nerve or other
tissue activities of
one or more peripheral nerves and/or surrounding tissues (e.g., epineurium,
perineurium,
endoneurium), and/or spinal cord and/or surrounding cerebral spinal fluid
and/or bone/cartilage.
[00112] In some embodiments of the apparatus, the at least one light source
includes a
vertical-cavity surface-emitting laser (VCSEL).
[00113] In some embodiments of the apparatus, the at least one light source
includes a
plurality of light sources, wherein the plurality of light sources includes a
one-dimensional array
of vertical-cavity surface-emitting lasers (VCSELs), and the at least one
light detector includes a
plurality of light detectors corresponding the plurality of light sources.
[00114] In some embodiments of the apparatus, at least one light source
includes a plurality
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of light sources, wherein the plurality of light sources includes a two-
dimensional array of
vertical cavity surface emitting lasers (VCSELs), and the at least one light
detector includes a
plurality of light detectors corresponding the plurality of light sources.
[00115] In some embodiments of the apparatus, the at least one light source
includes a micro-
light-emitting diode (micro-LED).
[00116] In some embodiments of the apparatus, the at least one light source
includes a
plurality of light sources, wherein the plurality of light sources includes a
one-dimensional array
of micro-light-emitting diodes (micro-LEDs), and the at least one light
detector includes a
plurality of light detectors corresponding the plurality of light sources.
[00117] In some embodiments of the apparatus, the at least one light source
includes a
plurality of light sources, wherein the plurality of light sources includes a
two-dimensional array
of micro-light-emitting diodes (micro-LEDs), and wherein the at least one
light detector includes
a plurality of light detectors corresponding the plurality of light sources.
[00118] In some embodiments of the apparatus, the volume of human tissue
further includes:
neuronal tissue of the human brain; a dura layer located on the neuronal
tissue of the human
brain; a skull layer located on the dura layer; and a skin layer located on
the skull layer. In some
such embodiments, the light pulse traverses through the skin layer, the skull
layer, and the dura
layer before encountering the neuronal tissue of the human brain. In some
embodiments, the
light pulse traverses through the skull layer and the dura layer before
encountering the neuronal
tissue of the human brain. In some embodiments, the light pulse traverses
through the dura layer
before encountering the neuronal tissue of the human brain. In some
embodiments, the at least
one light source is embedded into the skull layer and the light pulse
traverses through at least a
portion of the skull layer and through the entire dura layer before
encountering the neuronal
tissue of the human brain.
[00119] In some embodiments of the apparatus, the volume of human tissue
includes
neuronal tissue of a human brain. In some embodiments of the apparatus, the
volume of human
tissue includes neuronal tissue of a human spinal cord and/or surrounding
structures.
[00120] In some embodiments of the apparatus, the at least one light source
includes a
plurality of light sources and the at least one light detector includes a
plurality of light detectors,
wherein the plurality of light sources and the plurality of light detectors
are arranged
circumferentially around the volume of human tissue such that the plurality of
lights sources
alternates with the plurality of light detectors around the volume of human.
In some
embodiments of the apparatus, the at least one light source is located outside
the skull of a
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human and interacts with tissue of the brain inside the skull of the human.
[00121] In some embodiments of the apparatus, the wavelength of the light
pulse is between
about 650 nm and about 850 nm. In some embodiments of the apparatus, the
wavelength of the
light pulse is between about 700 nm and about 825 nm. In some embodiments of
the apparatus,
the wavelength of the light pulse is between about 775 nm and about 825 nm. In
some
embodiments of the apparatus, the wavelength of the light pulse is between
about 800 nm and
about 850 nm.
[00122] In some embodiments, the present invention provides a method that
includes
outputting a light pulse having a wavelength onto a volume of human tissue
such that the light
pulse interacts with the volume of human tissue; detecting neural-signal
activity by measuring a
light signal resulting from the interaction of the light pulse with the volume
of human tissue;
transmitting an electrical signal based on the reflected and transmitted light
signal; processing
the electrical signal; and outputting a response signal to a prosthetic device
based on the
processing of the electrical signal to control an action by the prosthetic
device.
[00123] In some embodiments of the method, the volume of human tissue includes
brain
tissue inside a human skull, and the outputting of the light pulse is done
outside the human skull.
In some embodiments of the method, the outputting a light pulse includes
configuring a vertical-
cavity surface-emitting laser (VCSEL) to emit light at a wavelength of about
675 nm to about
850 nm. In some embodiments of the method, the outputting a light pulse
includes configuring
a plurality of vertical-cavity surface-emitting lasers (VCSELs) to emit light
at a wavelength of
about 675 nm to about 850 nm. In some embodiments of the method, the
outputting a light
pulse includes configuring a micro-light-emitting diode (micro-LED) to emit
light at a
wavelength of about 675 nm to about 850 nm. In some embodiments of the method,
the
outputting a light pulse includes configuring a plurality of micro-light-
emitting diodes (micro-
LEDs) to emit light at a wavelength of about 675 nm to about 850 nm.
[00124] In some embodiments, the present invention provides a method that
includes signal
capture (detection) of neural activity using optical spectroscopy, and
outputting a control signal
based on the detected neural activity. In some embodiments, the neural
activity includes neural
activity of the central nervous system (i.e., the brain and/or spinal cord).
In some embodiments,
different geometry devices are used for the brain (e.g., detection of retro-
reflection or angled
scattering of one or more input optical pulses, wherein the devices have
emitters and detectors
that are all on one side of the tissue being observed), the spinal cord (e.g.,
detection of retro-
reflection or angled scattering of one or more input optical pulses or of
transmission of the light
pulses wherein the devices have emitters and detectors that are surrounding
the spinal-cord
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tissue being observed), and the peripheral nervous system (e.g., detection of
retro-reflection or
angled scattering of one or more input optical pulses or of transmission of
the light pulses
wherein the devices have emitters and detectors that are much closer to the
small-diameter the
peripheral nerves being observed). In some embodiments, the present invention
provides a
method that includes using of near-infrared spectroscopy (NIRS) and using time-
domain and/or
frequency-domain optical signal capture. In some embodiments, the present
invention provides
an apparatus that includes laser sources (such as semiconductor lasers) having
rise and/or fall
times on the order of ten (10) picoseconds in order to obtain spatial
resolutions on the order of
one (1) mm. In some embodiments, an emitter array that includes one or more
vertical-cavity
surface-emitting laser (VCSEL) arrays is used to emit pulses from a plurality
of locations (e.g., a
Cartesian grid) over an area of neural tissue to be observed.
[00125] In some embodiments, the emitter array selectively (e.g., under
control of a
microprocessor or other controller) emits light that has been amplitude-
modulated (i.e., intensity
modulated at, e.g., 50 MHz to 1 GHz and has an optical power on the order of,
e.g., tens to 100
microwatts ( W)). In some embodiments, the present invention uses pulses that
have a duration
of about 100 picosecond (ps), since, in some embodiments, little background
subtraction is
required with such a short pulse (which provides increased signal-to-noise (T
S/N) ratio).
[00126] In some embodiments, the present invention provides a method that
includes
measuring mean light intensity (DC) of the detected signal(s) as well as
amplitude (AC), and
phase of the detected waveform from a plurality of detectors. Some embodiments
use the
detected phase to determine the time-of-flight. Some embodiments scan through
a plurality of
intensity-modulation frequencies in order to reduce the number of detectors
required. Some
embodiments use a single frequency if they are operates in SRS (spatially
resolved
spectroscopy) mode.
[00127] In some embodiments, the emitted light pulses are all of a single
wavelength but are
amplitude modulated with a modulation frequency of between about 50 MHz and
about 1 GHz
or more, and the detectors are optionally wavelength-tuned or filtered to
detect the emitted
wavelength (e.g., the scattered light having the same wavelength as the
emitted wavelength),
wherein the neural activity changes the relative DC, AC amounts of the
detected wavelength as
well as the phase of the detected modulated light waveform. In some
embodiments, the emitted
light is also within an envelope of a pulse having a duration of about 1
nanosecond to about 1
microsecond. In other embodiments, the emitter array selectively (e.g., under
control of a
microprocessor or other controller) emits light pulses of a plurality of
different wavelengths, and
the detectors separately detect different wavelengths, in order to detect and
differentiate between
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different nerve activities (e.g., triggering CNAP pulse versus cell recovery
between CNAP
pulses) and/or differentiate between activity at different spatial locations
or depths. These
approaches are termed "frequency-domain" detection herein because of the use
of the intensity
modulation (e.g., having the frequency between about 50 MHz and about 1 GHz or
more) and
the phase detection, which is used to determine time-of-flight. In some
embodiments, such
approaches need not precisely determine the time the envelope of detected
pulses relative to the
emitted pulses because the phase detection provides that function. In some
embodiments, the
device outputs a control signal that is operatively coupled to control a
prosthetic device such as a
motorized robotic arm and hand, or leg and foot.
[00128] In some embodiments, the emitter array selectively (e.g., under
control of a
microprocessor or other controller) emits light pulses, wherein the emitted
light pulses have
sharp rise and/or fall times and/or are very short (e.g., having rise, fall,
or durations that are on
the order of about 10 picoseconds) and optionally are all of a single
wavelength, and the
detectors are very fast (and are optionally wavelength-tuned or filtered to
increase signal-to-
noise (S/N) ratios) to detect and differentiate a plurality of different time-
of-flight durations
(e.g., the scattered light having the same wavelength as the emitted
wavelength), wherein the
neural activity changes the relative amounts of scattering or reflection of
the emitted
wavelength. In other embodiments, the emitter array selectively (e.g., under
control of a
microprocessor or other controller) emits light pulses from different
locations, and the array of
detectors separately detect and differentiate the different time-of-flight
durations, in order to
determine and differentiate between different nerve-activity spatial locations
and/or depths. In
some embodiments, a signal-processing operation is performed on a plurality of
detected signals
to determine the location of the neural activity. These approaches are termed
"time-domain"
detection herein. In some embodiments, the device outputs a control signal
that is operatively
coupled to control a prosthetic device such as a motorized robotic arm and
hand, or leg and foot.
In other embodiments, the control signal is operatively coupled to drive a
closed-loop
neuroprosthesis or neuro-modulation device.
[00129] In some embodiments, the emitter array selectively (e.g., under
control of a
microprocessor or other controller) emits light pulses, wherein the emitted
light pulses are all of
a single wavelength, and the detectors are wavelength-tuned or filtered to
detect a plurality of
different wavelengths (e.g., the scattered light having the same wavelength as
the emitted
wavelength and/or one or more longer wavelengths of fluoresced light), wherein
the neural
activity changes the relative amounts of the plurality of detected
wavelengths. In other
embodiments, the emitter array selectively (e.g., under control of a
microprocessor or other
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controller) emits light pulses of different wavelengths, and the detectors
separately detect
different wavelengths, in order to detect and differentiate between different
nerve activities (e.g.,
triggering CNAP pulse versus cell recovery between CNAP pulses) and/or
differentiate between
activity at different spatial locations or depths. Both of these approaches
are termed
"wavelength-domain" detection herein. In some embodiments, such approaches
need not
precisely determine the time the detected pulses relative to the emitted
pulses-in some
embodiments, the location of the nerve activity is very close to the device
emitters and detectors
such that the detection of light by a particular detector specifies that the
neural activity was in
the location adjacent to that detector without needing to determine a time
(e.g., time-of-flight)
duration. In some embodiments, the device outputs a control signal that is
operatively coupled
to control a prosthetic device such as a motorized robotic arm and hand, or
leg and foot.
[00130] In some embodiments, the present invention provides a method that
includes
calibrating the device by associating a particular set of detected neural
activity to a particular
desired motor control, e.g., by empirically co-registering a functional image
(what movement the
patient desires to perform) to the sources and detectors that detect that
brain activity (the set of
spatially and temporally detected neural activities of various brain areas
detected by one or more
detectors using emitted light from one or more emitters, i.e., determining
that these detectors are
detecting neural activity resulting from the patient attempting middle finger
movement in the
upward direction).
[00131] In some embodiments of the method, the outputting of the light pulse
includes
intensity-modulating the light pulse at a frequency between about 50 MHz and
about 1000 MHz.
In some embodiments of the method, the light pulse traverses through the skin
layer, the skull
layer, and the dura layer and interacts with neuronal tissue of a human brain.
In some
embodiments of the method, the light pulse is intensity-modulated pulse at a
frequency between
about 50 MHz and about 1000 MHz. In some embodiments of the method, the
intensity-
modulated light pulse has a duration in a range of between about 10 ns and
about 1000 ns.
[00132] In some embodiments of the method, the outputting of the light pulse
is done from at
least one light source is embedded into the skull layer and the light pulse
traverses through at
least a portion of the skull layer and through the entire dura layer and then
interacts with
neuronal tissue of a human brain.
[00133] In some embodiments, the present invention provides a method that
includes
outputting a light pulse having a wavelength onto a volume of human tissue
such that the light
pulse interacts with the volume of human tissue; detecting neural signal
activity by measuring a
resulting light signal from the interaction; transmitting an electrical signal
based on the
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measured light signal; processing the electrical signal to generate a response
signal; and
outputting the response signal to a prosthetic device based on the processing
of the electrical
signal to effect an action by the prosthetic device.
[00134] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse is done outside a skull of a human and the volume of animal tissue
includes human brain
tissue inside the skull of the human.
[00135] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse includes emitting light at a wavelength of about 675 nm to about 850 nm
from a vertical-
cavity surface-emitting laser (VCSEL).
[00136] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse includes emitting light at a wavelength between about 675 nm to about
850 nm from a
micro-light-emitting diode (micro-LED).
[00137] In some embodiments of the prosthesis-control method, the light pulse
traverses
through the skin layer, the skull layer, and the dura layer and interacts with
neuronal tissue of a
human brain.
[00138] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse includes outputting a substantially square light pulse having a duration
between about 1 ps
and about 10 ps.
[00139] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse includes outputting a substantially square light pulse having a duration
between about 10
ps and about 100 ps.
[00140] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse includes intensity-modulating the light pulse at a frequency between
about 50 MHz and
about 1000 MHz. In some such embodiments, the intensity-modulated light pulse
has a duration
in a range of between about 10 ns and about 1000 ns.
[00141] In some embodiments of the prosthesis-control method, the outputting
of the light
pulse is done from at least one light source is embedded into the skull layer
and the light pulse
traverses through at least a portion of the skull layer and through the entire
dura layer and then
interacts with neuronal tissue of a human brain.
[00142] In some embodiments, the present invention provides a method that
includes
outputting a light pulse having a wavelength onto a volume of human tissue
such that the light
pulse interacts with the volume of human tissue; detecting neural signal
activity by measuring a
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resulting light signal from the interaction; transmitting an electrical signal
based on the
measured light signal; processing the electrical signal to generate a response
signal; and
outputting the response signal to a display device based on the processing of
the electrical signal
to display a spatial pattern of neural activity that changes over time.
[00143] In some embodiments of the display method, the outputting of the light
pulse is done
outside a skull of a human and the volume of animal tissue includes human
brain tissue inside
the skull of the human.
[00144] In some embodiments of the display method, the outputting of the light
pulse
includes emitting light at a wavelength of about 675 nm to about 850 nm from a
vertical-cavity
surface-emitting laser (VCSEL). In other embodiments, the outputting of the
light pulse
includes emitting light at a wavelength between about 675 nm to about 850 nm
from a micro-
light-emitting diode (micro-LED).
[00145] In some embodiments of the display method, the light pulse traverses
through the
skin layer, the skull layer, and the dura layer and interacts with neuronal
tissue of a human brain.
[00146] In some embodiments of the display method, the outputting of the light
pulse
includes outputting a substantially square light pulse having a duration
between about 1 ps and
about 10 ps. In other embodiments, the light pulse has a duration between
about 10 ps and about
100 ps.
[00147] In some embodiments of the display method, the outputting of the light
pulse
includes intensity-modulating the light pulse at a frequency between about 50
MHz and about
1000 MHz. In some such embodiments, the intensity-modulated light pulse has a
duration in a
range of between about 10 ns and about 1000 ns.
[00148] In some embodiments of the display method, the outputting of the light
pulse is done
from at least one light source is embedded into the skull layer and the light
pulse traverses
through at least a portion of the skull layer and through a dura layer and
then interacts with
neuronal tissue of a human brain.
[00149] In some embodiments, the present invention provides an apparatus that
includes
means for outputting a light pulse having a wavelength onto a volume of human
tissue such that
the light pulse interacts with the volume of human tissue; means for detecting
neural signal
activity by measuring a resulting light signal from the interaction and for
transmitting an
electrical signal based on the measured light signal; means for processing the
electrical signal to
generate a response signal; and means for outputting the response signal to a
prosthetic device
based on the processing of the electrical signal to effect an action by the
prosthetic device.
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Some embodiments further include the prosthetic device.
[00150] In some embodiments of this prosthetic apparatus, the means for
outputting of the
light pulse includes a vertical-cavity surface-emitting laser (VCSEL) that
emits light at laser
light at a wavelength of about 675 nm to about 850 nm.
[00151] In some embodiments of this prosthetic apparatus, the means for
outputting of the
light pulse includes means for intensity modulating the light pulse at a
frequency between about
50 MHz and about 1000 MHz. In some embodiments of this prosthetic apparatus,
the intensity-
modulated light pulse has a duration in a range of between about 10 ns and
about 1000 ns.
[00152] In some embodiments, the present invention provides an apparatus that
includes
means for outputting a light pulse having a wavelength onto a volume of human
tissue such that
the light pulse interacts with the volume of human tissue; means for detecting
neural signal
activity by measuring a resulting light signal from the interaction and for
transmitting an
electrical signal based on the measured light signal; means for processing the
electrical signal to
generate a response signal; and means for outputting the response signal to a
display device
based on the processing of the electrical signal to display a spatial pattern
of neural activity that
changes over time. In some embodiments of this display apparatus, the means
for outputting the
light pulse performs its operational function outside a skull of a human and
the volume of
animal tissue includes human brain tissue inside the skull of the human.
[00153] In some embodiments of this display apparatus, the means for
outputting the light
pulse includes a vertical-cavity surface-emitting laser (VCSEL) that emits
laser light at a
wavelength of about 675 nm to about 850 nm. In some embodiments of this
display apparatus,
the means for outputting the light pulse includes a micro-light-emitting diode
(micro-LED) that
emit light at a wavelength between about 675 nm to about 850 nm.
[00154] In some embodiments of this display apparatus, the means for
outputting the light
pulse includes means for intensity-modulating the light pulse at a frequency
between about 50
MHz and about 1000 MHz. In some embodiments, the intensity-modulated light
pulse has a
duration in a range of between about 10 ns and about 1000 ns.
[00155] It is to be understood that the above description is intended to be
illustrative, and not
restrictive. Although numerous characteristics and advantages of various
embodiments as
described herein have been set forth in the foregoing description, together
with details of the
structure and function of various embodiments, many other embodiments and
changes to details
will be apparent to those of skill in the art upon reviewing the above
description. The scope of
the invention should, therefore, be determined with reference to the appended
claims, along with
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the full scope of equivalents to which such claims are entitled. In the
appended claims, the
terms "including" and "in which" are used as the plain-English equivalents of
the respective
terms "comprising" and "wherein," respectively. Moreover, the terms "first,"
"second," and
"third," etc., are used merely as labels, and are not intended to impose
numerical requirements
on their objects.
41
