Note: Descriptions are shown in the official language in which they were submitted.
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GK-OEH-158
500638.20060
10
20 METHOD AND DEVICE FOR DETECTING NEUROLOGICAL AND PSYCHO-
PHYSIOLOGICAL STATES
The invention is directed to a biofeedback method for the detection
and self regulation of neurophysiological and psychophysiological states in
which a
user's biosignals are determined and evaluated and to a device for carrying
out the
method.
In particular, the invention enables the realization of a user-specific
biofeedback system for spontaneous and evoked brain activity and the
influencing
thereof in interactions with the physiological systems and is realized on the
basis of
a central unit and a portable unit.
REPLACEMENT SHEET (RULE 26)
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In the field of biofeedback, and particularly of EEG biofeedback or
neurofeedback, there exist different systems, devices and processes for use in
clinical practice as described, e.g., in the patents cited in the following.
US 5,740,812 concerns a method and apparatus for EEG biofeedback
while carrying out defined tasks, e.g., working at the computer, playing a
game, etc.
The associated apparatus comprises headphones to which EEG sensors are
attached.
The detected EEG signals are then evaluated by means of a computer and the
concentration and alertness of the human subject are indicated by means of
audio
feedback and visual feedback.
US 5,465,729 and US 5,343,871 describe devices for audio feedback
and video feedback in which audio-visual sequences simulate real scenes, so
that
desired psychic states can be induced. Activation of the desired physiological
parameters is rewarded. In so doing, control over these parameters is made
possible
by remembering the shown sequences.
US 5,406,957 discloses a biofeedback device for the feedback of
frequency bands determined by FFT. The feedback is presented in the form of
acoustic signals or spoken words.
US 5,036,858 shows a device for audio feedback and visual feedback
in which the calculated EEG frequency and the difference with respect to the
desired
frequency are presented simultaneously.
US 5,024,235 discloses a device for audio feedback and video
feedback in which the amplitude of an EEG frequency band is determined and is
displayed in comparison to a threshold.
US 3,890,957 describes a device for audio feedback in which a DC
signal is generated corresponding to the zero crossings determined in the
detected
signal and this DC signal is used for modulating an audio output.
In the apparatus for biofeedback known from US 3,821,949,
determined signal frequencies are determined in several channels
simultaneously
and corresponding acoustic signals are generated as output after reaching a
reference
value.
The commonest solutions with respect to technical equipment offer
the possibility of feeding back a plurality of physiological signals such as
EMG,
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Enclosure 2
Pages of specification to be exchanged
Page 3
temperature, breathing, skin conductivity and EEG. In the field of feedback of
human brain
activity, there are devices which achieve the feedback of different EEG
components such as theta
rhythms, alpha rhythms and beta rhythms, SMR rhythm or ratios of these brain
activities. The
existing devices offer the trainer the limited selection of determined
neurofeedback protocols,
wherein prescribed electrode positions are used. A biofeedback method that is
used very often
for a wide variety of different neuronal diseases is based, for example, on
the SMR rhythm.
However, this is usually carried out in a highly nonspecific manner because
the existing
technology does not offer enough flexibility or room for individualized
treatment.
Problems with the requirements for a successful biofeedback strategy grow out
of
the limitations of commercially available EEG technology: the measurement
hardware usually
does not allow reliable detection of specific signal components, the software
supplied is usually
oriented to routine EEG examinations and implements only conventional
evaluating processes.
A continuous online-capable monitoring of the changes in frequency and
amplitude of
fundamental rhythms is necessary for control of the feedback in EEG learning
processes. Known
EEG feedback controls are based on evaluations within longer time windows or
signal segments.
Therefore, acknowledgments of successful rhythm control are possible only in
intervals of
several seconds. In particular, there is a lack of high-resolution methods
with respect to time and
frequency and topographic methods by which the dynamics of brain processes can
be explored
online while taking into account the stochastic EEG character. Accordingly,
the preconditions
for understanding the delicate temporal microstructure of physiological and
pathological brain
events are nonexistent.
Further, practice has shown, for example, in the training of epileptic users
based
on slow potentials, that the biofeedback sessions should be conducted at least
2 to 3 times per
week over a period of several months. This is difficult to achieve in the case
of working or out-
of town users and this type of treatment is often discarded for this reason.
Difficulties also arise
in a follow-up phase in which
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the user has no possibility of monitoring the correctness of the exercises due
to the
lack of apparatus.
It is the object of the invention to provide a method and a device of
the type mentioned in the beginning with which specific indications of a
multiple,
personalized profile and for which a monitored initial training can be
detected and
which can also be applied outside of the training practice.
According to the invention, this object is met by a method containing
the features indicated in claim 1 and by a device containing the features
indicated in
claim 12:
Advantageous developments are indicated in the subclaims.
The invention makes it possible to realize a flexible, integrated
multichannel system comprising components for specifically indicating a
multiple,
personalized profile and for a monitored initial training. Based on the
protocol
which is adapted to this central system, transfer to a modular, individually
adjustable
mobile device for home use or for use outside the trainer's practice can be
earned
out, for example, for use during a follow-up phase. Accordingly, monitoring,
control and evaluation of the plurality of sessions taking place
simultaneously, but
not necessarily at the same location, and readjustment of the biofeedback
protocols
via Internet or communications protocols can also be realized.
The invention is characterized in particular by the following
advantages:
The invention is realized by a central system and portable miniature
system that can be coupled to this central system;
a profiler which is integrated in the central unit serves as a decision
support system for preparing a user-specific profile used as a basis for the
choice of
activities to be taught and the objective validation of the biofeedback
strategy by
means of signal-analytic processes and statistical tests compared to an
initial state
and a standard group;
a freely interactive arrangement of biofeedback protocols by the
trainer in the form of mathematical functions is possible, e.g.,
(Aa(OI)+ Aa(Oz)+ Aa(02))lA8(Oz)
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sum of the amplitudes of alpha activity under electrodes O1, Oz, 02
divided by the amplitude of the theta activity under electrode Oz
(P~10-12J(Oz))l(P~8-lOJOz))
ratio of the instantaneous output (electrode Oz) of the activity in the
S frequency range 10<=f<=12 Hz compared to activity in the frequency
range of 8<=f<10 Hz
F(P3)
instantaneous frequency of activity under electrode P3
ASMR(C3)
SMR amplitude - position C3
SCP(Cz)
Slow cortical potential under Cz
C(C4)
local coherence - position C4;
1 S the configuration of the software for the portable system is realized
by joining individual software components when setting the protocol in the
central
system and transferring from the central system to the portable system;
the monitoring, control and evaluation of the sessions and the
readjustment of the biofeedback protocols can be carried out through the
Internet
(for example, through the use of an integrated web chip) or by means of
communication protocols;
the monitoring and control of a plurality of sessions which take place
simultaneously but not necessarily at the same location and which are carned
out
with the portable system is made possible by means of the central system via a
2S biofeedback monitoring device within therapy offices, hospitals and studios
or by
means of biofeedback telemonitoring while training, e.g., at home;
the free choice of feedback channel or cortical localization (e.g.,
speech center, music center, etc..) can be carried out with simultaneous
monitoring
of the real signals and the feedback parameters of all detected channels at
the central
system;
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there is the possibility of simultaneous detection of EEG components
such as theta rhythms, alpha rhythms and beta rhythms and similar EEG rhythms
of
slow components (SCP) and other polygraphic signals;
the possibility of integrating interactions with other physiological
systems whose processes can be trained in a reinforcing manner is likewise
realized,
and their influences and the correlative and functional relationships with the
primary
feedback process is constantly monitored (example: monitoring and feedback of
the
relationship between slow brain potential and breathing);
there is the possibility of detecting abnormal brain activity,
particularly of epileptic graphic elements and the need for biofeedback
training;
further, there is the possibility of detection and feedback of evoked
potentials through the use of many visual, acoustic and cognitive stimuli at
the
central nervous system, for example, through coupling with a visual or
acoustic
perimeter or other visual, acoustic, somatosensory stimulation units;
it enables variable duration and capability of combining the feedback
trials, interstimulus intervals and pauses at the central system;
the choice of different signal processing methods or parameters for
the same channel or for different channels and their simultaneous display for
optimizing the feedback protocol at the central system;
the use of adaptive-recursive estimates as a basis for the continuous
online control of the feedback;
it contains multimedia feedback modules which can be configured
individually by the trainer or also by the user, as the case may be, by
selecting or
importing music files, film files, images or vibrations; the sensitivity of
the feedback
can also be set individually;
the control of films as feedback, for example, playing the film, is
carried out only until the corresponding activity is controlled in the desired
direction; otherwise, the playback is stopped;
the central system is advisably implemented as a two-monitor system
(user monitor and trainer monitor), either as a 2-PC system (communication via
RS232 or TCP/IP, for example) or as a 1-PC system with the use of internal
communications (e.g., DDE, TCP/IP);
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it enables compatibility with current polygraphic and EEG systems
and accordingly enables realization based on commercially available equipment
and
does not require any special hardware solution;
it is possible to choose between monitor, video panel, video glasses
or display worn on the head for feedback;
the portable miniature system can be realized on the basis of portable
computers, body-worn computers, palmtops or play stations.
The high degree of functionality and flexibility and the possibilities
for individual optimization not only increase the efficiency of neurofeedback
training, but new perspectives in treatment are also opened up by the design
of new
biofeedback protocols. Not least, the portable solution allows the user an
economical alternative that does not depend on appointments and accordingly
permits free planning. Further, by combining a central system with several
portable
systems, biofeedback monitoring spaces can be set up for monitoring the user
and
less personnel is required.
The invention will be described more fully in the following with
reference to an embodiment example.
In the accompanying drawings:
Figure 1 shows the sequence of method steps of the biofeedback
method according to the invention;
Figure 2 shows the flowchart of a neurofeedback training;
Figure 3 shows a schematic view of the neurofeedback system;
Figure 4 shows a function chart of the neurofeedback system; and
Figure 5 shows a block wiring diagram for a miniaturized portable
unit.
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P. age 8
As can be seen from Figure 1, the quantification of the EEG (QEEG) derived by
long-term monitoring forms the starting point of the method. In this way,
characteristic
quantities describing the state of the user can be obtained from the EEG that
was recorded while
resting or, depending upon the application, during different provocation
methods. By means of a
predefined vector of parameters, a user-specific profile is made. In addition
to the quantities
occurnng through the quantification, user-specific data such as, e.g.,
information about the
spontaneous emotional state and the environment, prior history, results of 1Q
test or
psychological tests, are also recorded in this profile. The user-specific
profile is then used for
determining the strategy in biofeedback. During the first biofeedback sessions
to be defined as
initial, a monitoring of the real signals and feedback parameters is carried
out via all detected
channels. A choice of different signal processing methods for one channel or
different channels
is also possible. After determining the optimal methods for the user - i.e.,
choice of activity,
cortical localization, calculation method, triggering of start of feedback,
and modalities of the
stimulation paradigms in case of evocation - a determined quantity of training
procedures can be
carned out either at the central system or at the home system (after
transferring the corresponding
modules). Long-term monitoring can then be carried out followed by
quantification. The profile
is continually expanded by the newly obtained parameters. Based on selected
statistical methods
and according to predefined criteria, comparisons can be made between the
state vectors . The
results are used to assess the success of the applied neurofeedback therapy.
The results of the
evaluation serve for adapting the treatment methods. This would mean that when
an activity is
not successfully controlled, this control can be replaced in future therapy
sessions by the control
of another activity or by combining the controlling of different EEG
parameters.
Figure 2 shows the sequence of a neurofeedback training.
As can be seen in Figure 3, the central biofeedback system comprises the
following components:
control of measurements and stimulation, signal detection, signal processing,
signal presentation,
feedback and stimulation (optional).
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The use of multi-channel derivations in neurofeedback investigations
is essential for the initial phase. This procedure allows an appreciable
improvement
in observation of the correlation of functional and morphological findings. It
is to
be expected that a user-specific and more effective neurofeedback therapy can
be
designed by taking into account the topographic peculiarities of the
pathological
EEG signals and by means of efficient online monitoring. Further, other
biological
signals should be derived simultaneously. In this way, valuable conclusions
can be
made about time-correlating accompanying phenomena or other physiological or
pathological processes and can be taken into account in the biofeedback.
In order to achieve the possibility of complete information about the
physiological processes taking place, polygraphic data containing, e.g., the
EEG,
VEOG, HEOG, EKG and breathing curve can be recorded. Positions of established
EEG derivation systems are used For derivation of the EEG. The derivations are
carned out referentially against the connected mastoids. Other montages such
as
transverse, longitudinal and temporal are possible. The transitional
impedances are
brought to values of less than 3 kS2. The filter is set in the range of 0 - 70
Hz, where
DC (0 Hz) is necessary predominantly with the derivation of slow potentials
(SCP).
The sampling rate is between 100 and 500 Hz. The derivation of the rest of the
signals is carried out in a bipolar manner. The EEG and EOG are carried out
using
offset- and drift-reducing electrodes. The breathing curve is recorded by
means of a
breathing belt. The biofeedback training following the initial examination and
feedback session is carried out using a sharply reduced quantity of electrodes
which
depends on the selection of activity.
Use of the neurofeedback system should be flexible and in so doing
should give the trainer the possibility of experimental examinations. For this
reason,
the preconditions should be created for monitoring both evoked and spontaneous
activities. In the first case, numerous stimulation procedures are required in
addition to the provocation methods established in the neurological routine.
SI-S2
paradigms, the oddball paradigms, visual stimulation by means of a
checkerboard or
perimeters are some examples of this.
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The demand for flexibility implies taking into account a greater
quantity of spontaneous and evoked brain activity components. Above all,
signals
are selected whose experimental use in the framework of a neurofeedback
procedure
was connected with a positive therapeutic effect. Examples of such EEG rhythms
are theta rhythm, alpha rhythm, beta rhythm, SMR rhythm or combinations
thereof.
The CNV, CPV, P300, VEP et al. belong to the field of ERP. Additional
relationships between different cortical localizations such as bilateral
asymmetries,
bilateral and local coherences are included. The superposition of relevant EEG
signals with a plurality of artifacts of biological and nonbiological origin
makes
efficient pre-processing indispensable. A compromise must be made in the
selection
of methods and algorithms for purposes of an optimal signal quality.
The signal processing routines form the core of a neurofeedback
system. The results of the evaluation of potentials are used in four different
ways:
for artifact reduction;
for presentation of results and monitoring by the trainer or medical
technician; a combination of the directly measured and calculated value can be
prepared and displayed;
for controlling feedback;
for subsequent offline evaluation of the neurofeedback session and
for statistical comparison with the preceding sessions or with existing
averages.
In the first three cases, only online-capable methods can be used or
methods in which the evaluations are carried out based on epochs (quasi-
online).
Methods of the following groups are implemented depending on the type of
calculation:
methods based on windows, e.g., the FFT, baseline calculation,
averaging, correlations, VEOG correction, HEOG correction;
recursive methods such as adaptive-recursive estimates (ARE).
Controlling by means of the control characteristic quantities
calculated from the measurement data gives the instantaneous state of feedback
for a
determined, measured physiological state of the user. The actual feedback
consists
in that this state is perceptible (e.g., acoustically, visually or audio-
visually) by the
user through a multimedia presentation and a change in this state, within the
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framework of the training procedure, is first detected by means of this
presentation
and can then be trained. The arrangement of the feedback should be carried out
in a
simple manner that is not too complex and should be age-dependent. In the
system
shown herein, the feedback is realized in the form of high-quality animation,
films,
musical pieces or vibrations that can be controlled via RS232, DDE or TCP/IP.
Movement-oriented and achievement-oriented types are implemented. It is
possible
to adapt the triggering of feedback to the possibilities of the user (within
the
individual parameter range of the signal to be controlled). The data files
required
for the control mechanism (images, music, films) can be introduced in
determined
formats as desired by the trainer and possibly by the user.
The basis of the central system is formed by a polygraphic EEG
device (DC-AC amplifier). This offers the possibility of flexible design of
the
measurement arrangements. A possible configuration would be, e.g., 28 unipolar
channels for EEG and 4 bipolar channels for VEOG, HEOG, EKG and breathing .
Figure 4 shows the function chart of the neurofeedback system. In
order to produce the required feedback, the data stream must first be
transferred
from the amplifier to the measurement computer. Subsequently, a characteristic
quantity used for controlling the feedback is calculated from the raw data.
The design of the control of the feedback by the three paths described
above (by RS323, DDE or TCP/IP) allows the central system to be realized
through
the use of two PCs and two screens or also by means of one PC and one or two
screens. The portable unit is realized based on portable computers, body-worn
computers, palmtops or play stations. Either current monitors, e.g., TFT
displays, or
special LCD glasses with integrated headphones, e.g., a personal LCD monitor
or
head-mounted display, can be used in the central and portable systems. The
above-
mentioned possibilities allow an additional miniaturization and mobile use of
the
portable solution. An arrangement of this kind is shown in the chart in Figure
5.
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ABBREVIATIONS
QEEG quantified EEG
EEG electroencephalogram
EKG electrocardiogram
BF biofeedback
NT neurotherapy
NF neurofeedback
S1, S2 stimulus
ISI interstimulus interval
SCP slow cortical potential
DSV digital signal processing
VEOG vertical electrooculogram
HEOG horizontal electrooculogram
DDE dynamic data exchange
EMG electromyogram
FFT fast Fourier transform
VEP visually evoked potential
ERP event-related potential
CNV contingent negative variation
CPV contingent positive variation
TCP/IP transmission control protocol over
Internet protocol
PC personal computer
EOG electrooculogram
