Feedback system

Abstract

To provide a feedback system capable of real-time feedback of information about hemisphere predominance whose individual difference is corrected, to a subject.SOLUTION: A feedback system includes: a measurement part measuring a brain activity level of the left cerebrum hemisphere of a subject and a brain activity level of the right cerebrum hemisphere of the subject by near infrared spectroscopy; a determination part determining baseline value; a correction part correcting the brain activity level of the left cerebrum hemisphere and the brain activity level of the right cerebrum hemisphere on the basis of the baseline value; an index calculation part calculating a laterilization index with a result of subtracting from a representative value of the brain activity level of the right cerebrum hemisphere a representative value of the brain activity level of the left cerebrum hemisphere as a numerator and with a result of adding up the representative value of the brain activity level of the left cerebrum hemisphere and the representative value of the brain activity level of the right cerebrum hemisphere as a denominator; an estimation part estimating hemisphere predominance on the basis of the laterilization index; a generation part generating sound or an image on the basis of the hemisphere predominance; and a presentation part presenting the generated sound or image to the subject.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a feedback system.

Background Art

[0002] As a method for measuring cerebral activity, near-infrared spectroscopy (NIRS) is known. In near-infrared spectroscopy, light including near-infrared light is irradiated from the scalp to the brain, and the cerebral activity is measured based on the ratio of the light absorbed by hemoglobin in the blood of the brain. Near-infrared spectroscopy has the advantages that it is easy to attach a measuring device to the head of a subject and has high tolerance to the body movement of the subject as compared with other methods for measuring cerebral activity. Therefore, near-infrared spectroscopy is often used not only for measuring the cerebral activity of adults but also for measuring the cerebral activity of infants.

[0003] Also, neurofeedback is known as a treatment method for mental diseases and cognitive decline. In neurofeedback, the cerebral activity of a subject is measured, and information based on the measured cerebral activity is fed back to the subject. By the subject's trial and error based on the fed-back information, the subject autonomously adjusts the cerebral activity, and as a result, the mental state of the subject becomes better.

[0004] In terms of language understanding and emotion, the difference between the cerebral activity of the left brain and the cerebral activity of the right brain is measured, and findings regarding the measurement result are obtained. Based on this finding, a neurofeedback system has been developed for the purpose of the subject autonomously adjusting the left-right difference in cerebral activity.

[0005] There are two forms of neurofeedback using near-infrared spectroscopy: an immediate form and a delayed form. In the immediate form of neurofeedback, the left-right difference index is calculated in real time based on the amount of brain activity measured according to the sampling period of the measuring device, and the information on hemispheric dominance estimated based on the left-right difference index is fed back to the subject in real time. In contrast, in the delayed form of neurofeedback, the left-right difference index is calculated based on the amount of brain activity measured within a certain period according to the sampling period of the measuring device, and the information on hemispheric dominance estimated based on the left-right difference index is fed back to the subject in non-real time.

[0006] In neurofeedback, for the hemoglobin concentration change amount "Hb" representing the change amount of the ratio of light absorbed by hemoglobin, the deviation (amplitude) from the baseline value is measured as the amount of brain activity. Also, the difference between the amount of activity in the left brain and the amount of activity in the right brain is calculated as the left-right difference index of the amount of brain activity, and the information on hemispheric dominance estimated based on the left-right difference index is fed back to the subject (see Non-Patent Document 1 and Non-Patent Document 2).

[0007] As the left-right difference index, the laterality index (LI) is known. The laterality index is expressed as in Equation (1).

[0008]

Equation

[0009] The laterality index expressed in Equation (1) is normalized by dividing the difference between the amount of activity in the left brain and the amount of activity in the right brain by the sum of the amount of activity in the left brain and the amount of activity in the right brain (the total amount of the subject's brain activity) (see Patent Document 1). As a result, in the laterality index expressed in Equation (1), individual differences in the total amount of brain activity are corrected.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Non-Patent Literature

[0011]

Non-Patent Literature 1

Non-Patent Literature 2

Summary of the Invention

Problems to be Solved by the Invention

[0012] However, in the lateralization index represented by Equation (1), when both the activity level of the left brain "Hb L " and the activity level of the right brain "Hb R " are negative values, the sign of the numerator "Hb L - Hb R " of the lateralization index and the sign of the denominator "Hb L + Hb R " of the lateralization index are reversed. In this case, since the positive or negative value of the lateralization index is reversed, there is a problem that the estimation result of which of the left brain or the right brain is dominant (hemisphere dominance) changes.

[0013] FIG. 26 is a diagram showing an example of changes in the lateralization index based on brain activity. When one of the activity levels of the left brain and the right brain is a positive value and the other is a negative value, and both the absolute value of the activity level of the left brain and the absolute value of the activity level of the right brain are sufficiently small, there is also a problem that the denominator of the lateralization index represented by Equation (1) becomes small, so that the lateralization index becomes an extremely large value.

[0014] As a countermeasure against these problems, in the above-described delayed form of neurofeedback, in order to prevent either the activity level of the left brain or the activity level of the right brain from becoming a negative value, the maximum amplitude (positive value) of the brain activity within a certain period is adopted as a parameter used for calculating the lateralization index. However, in the above-described immediate form of neurofeedback, there is a problem that information on hemispheric dominance with corrected individual differences cannot be fed back to the subject.

[0015] In view of the above circumstances, an object of the present invention is to provide a feedback system capable of real-time feedback to a subject of information on hemispheric dominance with corrected individual differences.

Means for Solving the Problems

[0016] One aspect of the present invention is a measurement unit that measures the brain activity amount of the left cerebral hemisphere and the brain activity amount of the right cerebral hemisphere of a subject at a predetermined cycle by near-infrared spectroscopy, and a baseline determination period defined within the rest period of the subject. A determination unit that determines a baseline value based on the amplitudes of the brain activity amounts of the left cerebral hemisphere and the right cerebral hemisphere so as to reduce the possibility that at least one of the brain activity amounts of the left cerebral hemisphere and the right cerebral hemisphere becomes a negative value during the subsequent feedback period; A correction unit that corrects the brain activity amount of the left cerebral hemisphere and the brain activity amount of the right cerebral hemisphere based on the baseline value during the feedback period; during the feedback period, the brain activity amount of the right cerebral hemisphere is subtracted from the representative value of the brain activity amount of the left cerebral hemisphere. Or, an index calculation unit that calculates a lateralization index with the result of subtracting the representative value of the brain activity amount of the left cerebral hemisphere from the representative value of the brain activity amount of the right cerebral hemisphere as the numerator and the result of adding the representative value of the brain activity amount of the left cerebral hemisphere and the representative value of the brain activity amount of the right cerebral hemisphere as the denominator; based on the lateralization index, An estimation unit that estimates the hemispheric dominance of the left cerebral hemisphere or the right cerebral hemisphere; and a generation unit that generates sound or an image based on the estimated hemispheric dominance, and presents the generated sound or the image to the subject. A feedback system comprising a presentation unit.

Advantages of the Invention

[0017] According to the present invention, it is possible to provide real-time feedback to the subject with information on hemispheric dominance corrected for individual differences.

Brief Description of the Drawings

[0018]

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Mode for Carrying Out the Invention

[0019] Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a feedback system 1 in an embodiment. The feedback system 1 is a system (neurofeedback system) that measures the brain activity levels of the left and right cerebral hemispheres of a subject and provides real-time feedback to the subject on the hemispheric dominance information with individual differences corrected based on a lateralization index (left-right difference index) corresponding to the measurement results. The feedback system 1 provides real-time feedback to the subject on the hemispheric dominance information using, for example, at least one of sound (auditory stimulus) and image (visual stimulus).

[0020] The feedback system 1 includes a measurement unit 2, a feedback device 3, and a presentation unit 4. The feedback device 3 may include the presentation unit 4. The feedback device 3 includes a storage device 31, a memory 32, an interface 33, a processing unit 34, and an operation unit 35. The processing unit 34 includes a determination unit 341, a correction unit 342, an index calculation unit 343, an estimation unit 344, and a generation unit 345.

[0021] The measurement unit 2 (measurement device) is detachably attached to the head of the subject. The measurement unit 2 measures the brain activity level of the left cerebral hemisphere and the brain activity level of the right cerebral hemisphere of the subject at a predetermined period (predetermined sampling period) by near-infrared spectroscopy (NIRS) such as continuous-wave near-infrared spectroscopy (CW-NIRS). The measurement unit 2 may be detachably attached near the left prefrontal cortex and the right prefrontal cortex of the subject. The measurement unit 2 may measure the brain activity level of the left prefrontal cortex of the subject as the brain activity level of the left cerebral hemisphere of the subject. The measurement unit 2 may measure the brain activity level of the right prefrontal cortex of the subject as the brain activity level of the right cerebral hemisphere of the subject.

[0022] The cerebral activity amount is represented by, for example, the amount of change in hemoglobin concentration. The amount of change in hemoglobin concentration is, for example, at least one of the amount of change in oxygenated hemoglobin concentration, the amount of change in deoxygenated hemoglobin concentration, and the amount of change in total hemoglobin concentration. The amount of change in hemoglobin concentration is obtained from a plurality of measurement channels of the measurement unit 2. The amount of change in hemoglobin concentration may be obtained from each measurement channel attached near each of the left cerebral hemisphere and the right cerebral hemisphere of the subject, or may be obtained from each measurement channel of the measurement unit 2 attached at any position capable of measuring the cerebral activity amount of the left cerebral hemisphere and the right cerebral hemisphere of the subject. The measurement unit 2 transmits the measurement results of the time-series cerebral activity amount to the interface 33 using a wireless line or a wired line.

[0023] The feedback device 3 is an information processing device, for example, a personal computer, a tablet terminal, or a smartphone terminal. A program stored in a storage device 31 having a non-volatile recording medium (non-temporary recording medium) is expanded in a memory 32, and when a processor such as a CPU (Central Processing Unit) executes the expanded program, some or all of the functional units of the feedback device 3 are realized as software. The program may be recorded on a computer-readable recording medium. A computer-readable recording medium is, for example, a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD-ROM (Compact Disc Read Only Memory), a hard disk built in a computer system, and a non-temporary recording medium such as a storage device such as a solid state drive.

[0024] Some or all of the functional units of the feedback device 3 may be realized using hardware including an electronic circuit (electronic circuit or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0025] FIG. 2 is a diagram showing an example of a training period, a resting period, and a neurofeedback period. The training period (neurofeedback training period) consists of a resting period “T REST ” and a neurofeedback period “T NF ”.

[0026] During the resting period “T REST ”, the brain activity of the subject at rest is measured. The neurofeedback period “T NF ” is a period in which the subject tries and makes mistakes to achieve a predetermined task based on the hemispheric dominance information feedbacked (presented) in real time. The task is not limited to a specific task, but for example, is a task of making the state of hemispheric dominance approach the target state. During the neurofeedback period, at least one of sound (auditory stimulus) and image (visual stimulus) is feedbacked to the subject in real time according to the brain activity amount of the left cerebral hemisphere and the brain activity amount of the right cerebral hemisphere of the subject (according to the state of hemispheric dominance).

[0027] There is a finding that the amplitude of the change in spontaneous hemoglobin concentration obtained by near-infrared spectroscopy (frequency band: 0.01 - 0.05 Hz) is related to the spontaneous potential fluctuations obtained from electroencephalograms (Reference 1: Chen et al. (2020), ‘Amplitude of fNIRS Resting-State Global Signals Is Related to EEG Vigilance Measures: A Simultaneous fNIRS and EEG Study’, Frontiers in Neuroscience, Volume 14.). Although the length of the rest period is not limited to a specific length, based on this finding, the length of the rest period is, for example, about 5 to 50 seconds. Also, the neurofeedback period is about 30 to 60 seconds.

[0028] Returning to FIG. 1, the description of the configuration example of the feedback system 1 will be continued. The interface 33 acquires the measurement results of the time-series brain activity amount from the measurement unit 2. The interface 33 records the measurement results of the time-series brain activity amount in the storage device 31.

[0029] The determination unit 341 acquires the measurement results of the time-series brain activity amount from the storage device 31. The determination unit 341 determines the baseline value so as to reduce the possibility that at least one of the brain activity amounts of the left cerebral hemisphere and the right cerebral hemisphere becomes a negative value during the feedback period (neurofeedback period) following the rest period, based on the amplitudes of the brain activity amounts of the left cerebral hemisphere and the right cerebral hemisphere during the baseline determination period defined within the rest period.

[0030] The correction unit 342 corrects (offsets) the brain activity amounts of the left cerebral hemisphere and the right cerebral hemisphere based on the baseline value during the feedback period.

[0031] The lateralization index calculation unit 343 calculates the lateralization index "LI" as shown in Equation (2), with the result "L - R" obtained by subtracting the representative value "R" of the brain activity level of the right cerebral hemisphere from the representative value "L" of the brain activity level of the left cerebral hemisphere for a certain period of time immediately before the current time, for example, during the feedback period, as the numerator, and the result "L + R" obtained by adding the representative value "L" of the brain activity level of the left cerebral hemisphere and the representative value "R" of the brain activity level of the right cerebral hemisphere as the denominator. The representative value is, for example, a moving average value or a moving median value.

[0032] [Number]

[0033] The lateralization index calculation unit 343 may also calculate the lateralization index "LI" as shown in Equation (3), with the result "R - L" obtained by subtracting the representative value "L" of the brain activity level of the left cerebral hemisphere from the representative value "R" of the brain activity level of the right cerebral hemisphere for a certain period of time immediately before the current time, for example, during the feedback period, as the numerator, and the result "R + L" obtained by adding the representative value "L" of the brain activity level of the left cerebral hemisphere and the representative value "R" of the brain activity level of the right cerebral hemisphere as the denominator.

[0034] [Number]

[0035] The estimation unit 344 estimates the hemispheric dominance of the left cerebral hemisphere or the right cerebral hemisphere based on the lateralization index. That is, the estimation unit 344 estimates which of the left cerebral hemisphere or the right cerebral hemisphere is dominant based on the lateralization index. The generation unit 345 generates sound or an image based on the estimated hemispheric dominance.

[0036] The presentation unit 4 is a display device having, for example, a liquid crystal display or the like. The presentation unit 4 presents the generated image to the subject. The presentation unit 4 may present the generated predetermined index image to the subject as an image of the fixation point. The presentation unit 4 may present an operable operation key image (operation button image). The presentation unit 4 may be, for example, an audio processing device to which a speaker or headphones or the like is connected. The presentation unit 4 presents the generated sound to the subject.

[0037] The operation unit 35 is an operation device such as a keyboard, a mouse, and a touch panel. When the operation unit 35 is a touch panel, an operation key image may be displayed on the touch panel. The operation unit 35 receives, for example, an operation by the user. The operation unit 35 outputs a signal corresponding to the operation to the processing unit 34. The signal corresponding to the operation is, for example, a signal instructing the start or end of training.

[0038] Next, the details of the feedback system 1 will be described. FIG. 3 is a diagram showing an example of the amount of brain activity during the baseline determination period. The length of the baseline determination period “T” defined within the rest period is equal to or less than the length of the rest period. The measurement unit 2 measures the amount of brain activity in the left cerebral hemisphere and the amount of brain activity in the right cerebral hemisphere of the subject at a predetermined sampling period by near-infrared spectroscopy. BASELINE The determination unit 341 determines the average value “M” of the amount of brain activity in the left cerebral hemisphere based on the amplitude of the amount of brain activity in the left cerebral hemisphere during the baseline determination period defined within the rest period, in order to determine the baseline value (reference value) of the amplitude of the amount of brain activity (change amount of hemoglobin concentration) during the neurofeedback period. Also, the determination unit 341 determines the average value “M” of the amount of brain activity in the right cerebral hemisphere based on the amplitude of the amount of brain activity in the right cerebral hemisphere during the baseline determination period defined within the rest period.

[0039] FIG. 4 is a diagram showing an example of the average value “M” of the amount of brain activity during the baseline determination period. In order to determine the baseline value (reference value) of the amplitude of the amount of brain activity (change amount of hemoglobin concentration) during the neurofeedback period, the determination unit 341 determines the average value “M” of the amount of brain activity in the left cerebral hemisphere based on the amplitude of the amount of brain activity in the left cerebral hemisphere during the baseline determination period defined within the rest period. L Also, the determination unit 341 determines the average value “M” of the amount of brain activity in the right cerebral hemisphere based on the amplitude of the amount of brain activity in the right cerebral hemisphere during the baseline determination period defined within the rest period. R

[0040] FIG. 5 is a diagram showing an example of the difference (absolute value) between the amplitude of the brain activity amount in the left cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the left cerebral hemisphere during the baseline determination period. The determination unit 341 determines the absolute value "A" (n is the identification number of the sample) of the difference between the amplitude of the brain activity amount in the left cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the left cerebral hemisphere. L During the baseline determination period, the determination unit 341 determines the absolute value "A" (n is the identification number of the sample) of the difference between the amplitude of the brain activity amount in the left cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the left cerebral hemisphere. L " of the difference between the amplitude of the brain activity amount in the left cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the left cerebral hemisphere. Ln " (n is the identification number of the sample).

[0041] FIG. 6 is a diagram showing an example of the difference (absolute value) between the amplitude of the brain activity amount in the right cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the right cerebral hemisphere during the baseline determination period. The determination unit 341 determines the absolute value "A" (n is the identification number of the sample) of the difference between the amplitude of the brain activity amount in the right cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the right cerebral hemisphere. R During the baseline determination period, the determination unit 341 determines the absolute value "A" (n is the identification number of the sample) of the difference between the amplitude of the brain activity amount in the right cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the right cerebral hemisphere. R " of the difference between the amplitude of the brain activity amount in the right cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the right cerebral hemisphere. Rn " (n is the identification number of the sample).

[0042] FIG. 7 is a diagram showing an example of the maximum value of the difference (absolute value) between the amplitude of the brain activity amount in the cerebral hemisphere and the average value "M" of the amplitude of the brain activity amount in the cerebral hemisphere during the baseline determination period for each of the left cerebral hemisphere and the right cerebral hemisphere. The determination unit 341 extracts the maximum amplitude "A" from the absolute values "A" of the difference in the brain activity amount in the left cerebral hemisphere during the baseline determination period. The determination unit 341 extracts the maximum amplitude "A" from the absolute values "A" of the difference in the brain activity amount in the right cerebral hemisphere during the baseline determination period. Ln " of the difference, and extracts the maximum amplitude "A". LMAX " from the absolute values "A" of the difference in the brain activity amount in the left cerebral hemisphere during the baseline determination period. The determination unit 341 extracts the maximum amplitude "A" from the absolute values "A" of the difference in the brain activity amount in the right cerebral hemisphere during the baseline determination period. Rn " of the difference, and extracts the maximum amplitude "A". RMAX " from the absolute values "A" of the difference in the brain activity amount in the right cerebral hemisphere during the baseline determination period.

[0043] FIG. 8 is a diagram showing an example of the maximum value of the difference (absolute value) between the amplitude of the brain activity amount in the cerebral hemisphere and the average value of the amplitude of the brain activity amount in the cerebral hemisphere during the baseline determination period. The determination unit 341 determines the larger amplitude between the maximum amplitude "A" of the brain activity amount in the left cerebral hemisphere and the maximum amplitude "A" of the brain activity amount in the right cerebral hemisphere as the maximum amplitude value "A" of the spontaneous brain activity during the baseline determination period. LMAX " of the brain activity amount in the left cerebral hemisphere and the maximum amplitude "A" of the brain activity amount in the right cerebral hemisphere as the maximum amplitude value "A" of the spontaneous brain activity during the baseline determination period. RMAX " of the brain activity amount in the right cerebral hemisphere, and determines the larger amplitude as the maximum amplitude value "A" of the spontaneous brain activity during the baseline determination period. MAX " of the spontaneous brain activity during the baseline determination period.

[0044] FIG. 9 is a diagram showing an example of a baseline value determined during a baseline determination period. The determination unit 341 determines the maximum amplitude "A" of the brain activity amount in the left cerebral hemisphere during the baseline determination period. LMAX " and the maximum amplitude "A" of the brain activity amount in the right cerebral hemisphere during the baseline determination period. RMAX " of the larger amplitude "A" among them and the weight coefficient "ω", and determines the baseline value "ωA" of the amplitude during the neurofeedback period "T". MAX " based on NF " MAX ".

[0045] It is desirable that the weight coefficient "ω" be a positive value of an appropriate magnitude so that the brain activity amount measured during the neurofeedback period following the rest period does not become a negative value. Here, it is desirable that the weight coefficient "ω" not be a positive value of an excessive magnitude so that the brain activity amount measured during the neurofeedback period does not become too large.

[0046] FIG. 10 is a diagram showing an example of the correction of the brain activity amount during the neurofeedback period. During the neurofeedback period following the baseline determination period, the correction unit 342 corrects (offsets) the measured brain activity amount so that the baseline value of the measured brain activity amount becomes "ωA". Specifically, the correction unit 342 adds "-M + ωA" to the brain activity amount "x" of the left cerebral hemisphere based on the average value "M" of the amplitude of the brain activity amount of the left cerebral hemisphere and the baseline value "ωA". The correction unit 342 adds "-M + ωA" to the brain activity amount "x" of the right cerebral hemisphere based on the average value "M" of the amplitude of the brain activity amount of the right cerebral hemisphere and the baseline value "ωA". MAX " L " MAX " L " L " MAX " R " MAX " R " R " MAX ".

[0047] FIG. 11 is a diagram showing an example of the moving average of the amount of brain activity during the neurofeedback period. The index calculation unit 343 calculates a representative value "L" of the amount of brain activity in the left cerebral hemisphere for a certain period "T" immediately before the current time, for example, during the neurofeedback period, for each measured amount of brain activity in the left cerebral hemisphere. MARGINE The index calculation unit 343 calculates a representative value "R" of the amount of brain activity in the right cerebral hemisphere for a certain period "T" immediately before the current time, for example, during the neurofeedback period, for each measured amount of brain activity in the right cerebral hemisphere. MARGINE

[0048] The length of the certain period "T" is equal to or less than the length of the baseline determination period. Based on the finding that the fluctuation of cerebral blood flow derived from neural activity has a delay of about 5 seconds (see the above-mentioned reference 1), the length of the certain period "T" is, for example, about 5 seconds. The index calculation unit 343 calculates a lateralization index based on the representative value "L" of the amount of brain activity in the left cerebral hemisphere and the representative value "R" of the amount of brain activity in the right cerebral hemisphere for a certain period "T" immediately before the current time during the neurofeedback period. MARGINE MARGINE MARGINE

[0049] FIG. 12 is a diagram showing, for each weight coefficient "ω", an example of the ratio (Negative Value Ratio) of the number of samples of the amount of brain activity that is still negative even after correction to the total number of samples of the amount of brain activity during the neurofeedback period. The ratio of the number of samples of the amount of brain activity that is still negative even after correction is expressed as in Equation (4).

[0050]

Equation

[0051] Here, "N" NF represents the total number of samples during the neurofeedback period. "K" NF represents the number of samples of the amount of brain activity that is still negative even after correction in a certain period "T" immediately before the current time. MARGINE

[0052] ​​​​​ FIG. 13 is a diagram showing an example of a weight coefficient "ω" used for a subject during a neurofeedback period. That is, FIG. 13 shows an example of an ideal weight coefficient "ω" associated with an individual.

[0053] FIG. 14 is a diagram showing an example of a weight coefficient "ω" used for a group of subjects during a neurofeedback period. That is, FIG. 14 shows an example of an ideal weight coefficient "ω" associated with a group. Whether the weight coefficient for a subject (individual) or the weight coefficient for a group of subjects (group) is used for training can be switched (selected) based on an instruction operation by the user of the feedback system 1.

[0054] FIG. 15 is a diagram showing an example of a change in a lateralization index based on brain activity corrected to reduce the possibility of becoming a negative value during a neurofeedback period. The lateralization index based on the corrected brain activity does not become a huge value like the lateralization index illustrated in FIG. 26 and is stable.

[0055] The generation unit 345 generates sound or an image based on the hemispheric dominance estimated by the estimation unit 344. Here, the generation unit 345 generates a sound or an image corresponding to the lateralization index as information on the estimated hemispheric dominance. The generation unit 345 may generate a sound or an image representing the numerical value of the lateralization index itself as information on the estimated hemispheric dominance.

[0056] FIG. 16 is a diagram showing a display example of a first index image corresponding to a lateralization index during a neurofeedback period. In FIG. 16, the information on hemispheric dominance is represented by an image having a size corresponding to the lateralization index. The generation unit 345 may generate a first index image 103 including a lateralization index image 101 having a size corresponding to the lateralization index inside a target image 102 as information on the estimated hemispheric dominance. The diameter of the target image 102 is constant regardless of the lateralization index. The presentation unit 4 displays the first index image 103.

[0057] FIG. 17 is a diagram showing an example of display of a first index image that changes according to a lateralization index during the neurofeedback period. During the neurofeedback period, the subject tries to achieve the task of making the left cerebral hemisphere dominant over the right cerebral hemisphere while gazing at the displayed first index image 103. In the first index image 103, as an example, the generation unit 345 increases the diameter of the lateralization index image 101 with the diameter of the target image 102 as the upper limit as the left cerebral hemisphere becomes more dominant over the right cerebral hemisphere.

[0058] FIG. 18 is a diagram showing an example of display of a second index image according to a lateralization index during the neurofeedback period. In FIG. 18, the information on hemisphere dominance is represented by sounds and images of sizes according to the lateralization index. The generation unit 345 may generate a second index image 201 representing the volume and sound pressure according to the lateralization index as the estimated information on hemisphere dominance. Further, the generation unit 345 causes white noise with a volume and sound pressure according to the lateralization index to be output from the presentation unit 4.

[0059] FIG. 19 is a diagram showing an example of display of a second index image that changes according to a lateralization index during the neurofeedback period. During the neurofeedback period, the subject tries to achieve the task of making the left cerebral hemisphere dominant over the right cerebral hemisphere while gazing at the displayed second index image 201. In the second index image 201, as an example, the generation unit 345 makes the decibel value displayed for the sound pressure of the white noise a smaller value as the left cerebral hemisphere becomes more dominant over the right cerebral hemisphere. The generation unit 345 reduces the number of arc images representing the volume of the white noise in the second index image 201 as the left cerebral hemisphere becomes more dominant over the right cerebral hemisphere. Further, the generation unit 345 reduces the volume and sound pressure of the white noise output from the presentation unit 4 as the left cerebral hemisphere becomes more dominant over the right cerebral hemisphere.

[0060] Next, an operation example of the feedback system 1 will be described. FIG. 20 is a flowchart showing an operation example of the feedback system 1 in the embodiment. The measurement unit 2 measures the brain activity amount of the left cerebral hemisphere of the subject and the brain activity amount of the right cerebral hemisphere of the subject at a predetermined sampling period during a baseline determination period defined within the rest period of the subject (step S101). The determination unit 341 determines a baseline value based on the amplitude of the brain activity amount of the left cerebral hemisphere and the amplitude of the brain activity amount of the right cerebral hemisphere during a baseline determination period defined within the rest period of the subject (step S102).

[0061] The measurement unit 2 measures the brain activity amount of the left cerebral hemisphere of the subject and the brain activity amount of the right cerebral hemisphere of the subject at a predetermined sampling period during a neurofeedback period following the rest period (step S103). The correction unit 342 corrects the brain activity amount of the left cerebral hemisphere and the brain activity amount of the right cerebral hemisphere based on the baseline value during the neurofeedback period (step S104). The index calculation unit 343 calculates a lateralization index based on the representative value "L" of the brain activity amount of the left cerebral hemisphere and the representative value "R" of the brain activity amount of the right cerebral hemisphere for a certain period immediately before the current time during the neurofeedback period (step S105).

[0062] The estimation unit 344 estimates the hemispheric dominance of the left cerebral hemisphere or the right cerebral hemisphere based on the lateralization index (step S106). The generation unit 345 generates a sound or an image based on the estimated hemispheric dominance (step S107). The presentation unit 4 presents the generated image or sound to the subject (step S108).

[0063] The determination unit 341 determines whether to end the training period (step S109). If the determination unit 341 determines to end the training period (step S109: YES), the feedback system 1 ends the training period. If the determination unit 341 determines to continue the training period (step S109: NO), the feedback system 1 returns the process to step S103.

[0064] Note that the feedback system 1 may update the baseline value based on the larger amplitude of the maximum amplitude of the brain activity of the left cerebral hemisphere and the maximum amplitude of the brain activity of the right cerebral hemisphere at a predetermined timing during the neurofeedback period. This can reduce the possibility that the measurement result of the brain activity becomes a negative value due to the baseline value becoming inappropriate over time.

[0065] As described above, the measurement unit 2 measures the brain activity of the left cerebral hemisphere (left brain activity) and the brain activity of the right cerebral hemisphere (right brain activity) of the subject at a predetermined sampling period by near-infrared spectroscopy (NIRS). The measurement unit 2 may measure the brain activity of the left prefrontal cortex as the brain activity of the left cerebral hemisphere of the subject. The measurement unit 2 may measure the brain activity of the right prefrontal cortex as the brain activity of the right cerebral hemisphere of the subject. The determination unit 341 determines, based on the amplitude "A RESET " of the brain activity of the left cerebral hemisphere and the amplitude "A BASELINE " of the brain activity of the right cerebral hemisphere during the baseline determination period "T L " defined within the rest period "T R " of the subject, to reduce the possibility that at least one of the brain activity of the left cerebral hemisphere and the brain activity of the right cerebral hemisphere becomes a negative value during the feedback period (neurofeedback period "T RESET ") following the rest period "T NF ". For example, the determination unit 341 determines the baseline value "ωA RESET " based on the larger amplitude "A BASELINE " of the maximum amplitude of the brain activity of the left cerebral hemisphere during the baseline determination period "T LMAX " defined within the rest period "T RESET ", the maximum amplitude "A BASELINE " of the brain activity of the right cerebral hemisphere during the baseline determination period "T RMAX " defined within the rest period "T MAX ", and the weighting coefficient "ω". MAX "

[0066] During the feedback period, the correction unit 342 corrects (offsets) the cerebral activity amount of the left cerebral hemisphere and the cerebral activity amount of the right cerebral hemisphere based on the baseline value.

[0067] The index calculation unit 343 uses, as the numerator, the result "L - R" obtained by subtracting the representative value "R" of the cerebral activity amount of the right cerebral hemisphere from the representative value "L" of the cerebral activity amount of the left cerebral hemisphere, and, as the denominator, the result "L + R" obtained by adding the representative value "L" of the cerebral activity amount of the left cerebral hemisphere and the representative value "R" of the cerebral activity amount of the right cerebral hemisphere, for a certain period immediately before the current time (for example, 5 seconds immediately before the current time) during the feedback period, to calculate the lateralization index "(L - R) / (L + R)". Further, the index calculation unit 343 may use, as the numerator, the result "R - L" obtained by subtracting the representative value "L" of the cerebral activity amount of the left cerebral hemisphere from the representative value "R" of the cerebral activity amount of the right cerebral hemisphere, and, as the denominator, the result "R + L" obtained by adding the representative value "L" of the cerebral activity amount of the left cerebral hemisphere and the representative value "R" of the cerebral activity amount of the right cerebral hemisphere, for a certain period immediately before the current time during the feedback period, to calculate the lateralization index "(R - L) / (R + L)". The representative value is, for example, a moving average value or a moving median value.

[0068] The estimation unit 344 estimates the hemispheric dominance of the left cerebral hemisphere or the right cerebral hemisphere based on the lateralization index. The generation unit 345 generates a sound or an image based on the estimated hemispheric dominance. The presentation unit 4 (display device) presents the generated image to the subject. The presentation unit 4 (audio processing device and speaker) presents the generated sound to the subject.

[0069] As a result, it is possible to provide real-time feedback to the subject with information on hemispheric dominance in which individual differences are corrected.

[0070] (Effect example) The physical phenomenon "agari", in which performance cannot be demonstrated as usual due to psychological pressure, is known to be a physical phenomenon related to the left-right difference in the cerebral hemispheres. For example, when the brain activity in the cerebral hemispheres is in a left-dominant state, the motor performance is high. On the other hand, when the brain activity in the cerebral hemispheres is in a right-dominant state, the motor performance is low. Therefore, the results of an experiment to verify the effect of improving motor performance even under psychological pressure are shown below as an example of the effect of neurofeedback training using the feedback system 1 (system with offset).

[0071] The subjects underwent neurofeedback training using the feedback system 1 to adjust the left-right difference in brain activity in the cerebral hemispheres to a left-dominant state. It was verified whether the neurofeedback training could improve the motor performance even under psychological pressure.

[0072] The experimental period was a total of 5 days, consisting of a pre-test period (1 day), a neurofeedback training period (3 days) after the pre-test period, and a post-test period (1 day) after the neurofeedback training period. The pre-test period consisted of a practice period and a main event period. Similarly, the post-test period consisted of a practice period and a main event period.

[0073] Figure 21 is a diagram showing an example of the experimental protocol. During the pre-test period, the subject wearing the measurement unit 2 on the head threw darts, and the dart performance was measured. During the practice period of the pre-test period, a single subject performed a total of 5 dart throws (all 5 sessions of practice trials) in a non-pressure environment (non-competitive format). During the main event period of the pre-test period, the subject performed a total of 5 dart throws (all 5 sessions of main event trials) in a pressure environment (2 vs. 2 competitive format).

[0074] During the pre-test period, the subject threw darts according to the following protocol (i), (ii), (iii). (i) A rest period (10 seconds) during which the subject lowers their own hand, does not pay attention to dart throwing, and relaxes (ii) A concentration period (10 seconds) during which the subject holds a dart arrow and concentrates on dart throwing (iii) A rest period (10 seconds) after dart throwing during which the subject lowers their own hand, does not pay attention to dart throwing, and relaxes

[0075] During the neurofeedback training period after the pre-test period, the subject performed trial-and-error training 5 times a day using the feedback system 1 to make the left-right difference in the cerebral hemispheres of the subject in a left-dominant state. Specifically, the subject performed trial-and-error training to reduce the volume and sound pressure of the white noise output from the presentation unit 4 while gazing at the second index image 201 displayed on the presentation unit 4.

[0076] The subject underwent neurofeedback training (NF training) according to the following protocol followed by (A) and (B). (A) A rest period (30 seconds) (B) A neurofeedback period (60 seconds)

[0077] The baseline value was set at 1 mM·mm. The sampling frequency of the brain activity amount was 10 Hz. Dart performance data was acquired using the back surface of the magnetic dart board. The maximum radius of the magnetic dart board is 17 cm.

[0078] By applying a band-pass filter to the measured brain activity amount, a low-frequency fluctuation component (a fluctuation component of 0.01 - 0.05 Hz) was extracted from the measured brain activity amount. As an index representing the magnitude of the amplitude of the low-frequency fluctuation component, the sum of the differential values (absolute values) of the low-frequency fluctuation component was calculated. Using this calculated sum as a parameter, a laterality index (LI) was calculated for each of the left and right cerebral hemispheres.

[0079] The change amount "X" of hemispheric dominance (left - right difference in brain activity) by neurofeedback training was defined as "X = (the maximum value of the laterality index in all 5 sessions on the 3rd day) - (the maximum value of the laterality index in all 5 sessions on the 1st day)".

[0080] The distance from the center of the magnetic dartboard to the dart stuck in the magnetic dartboard was defined as the error value. Dart performance was defined as "Dart performance = 17 - error value" based on the maximum radius of the magnetic dartboard. Also, the dart performance "Y" in a pressure environment was defined as "Y = (the average value of dart performance in the official trial) - (the average value of dart performance in the practice trial)".

[0081] Figure 22 is a diagram showing an example of the average dart performance (average value of dart performance) before neurofeedback training. Figure 23 is a diagram showing an example of the average dart performance after neurofeedback training. Figure 24 is a diagram showing an example of the average dart performance of the official trial based on the practice trial.

[0082] The subjects who underwent neurofeedback training using the feedback system 1 (system with offset) improved their motor performance (average dart performance) in a pressure environment more than the subjects who underwent neurofeedback training using a system without offset.

[0083] Figure 25 is a diagram showing an example of the change amount of hemispheric dominance (left - right difference in brain activity) from the 1st day to the 3rd day. The subjects who underwent neurofeedback training using the feedback system 1 (system with offset) changed the hemispheric dominance to a left - dominant state more than the subjects who underwent neurofeedback training using a system without offset.

[0084] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and designs and the like within the scope not departing from the gist of the present invention are also included.

Explanation of Signs

[0085] 1... Feedback system, 2... Measurement unit, 3... Feedback device, 4... Presentation unit, 31... Storage device, 32... Memory, 33... Interface, 34... Processing unit, 35... Operation unit, 101... Lateralization index image, 102... Target image, 103... First index image, 201... Second index image, 341... Decision unit, 342... Correction unit, 343... Index calculation unit, 344... Estimation unit, 345... Generation unit

Claims

1. A measurement unit that measures the brain activity level of the left cerebral hemisphere of a subject and the brain activity level of the right cerebral hemisphere of the subject at a predetermined cycle by near-infrared spectroscopy; Based on the amplitudes of the brain activity levels of the left cerebral hemisphere and the amplitudes of the brain activity levels of the right cerebral hemisphere during a baseline determination period defined within the rest period of the subject, a determination unit that determines a baseline value so as to reduce the possibility that at least one of the brain activity levels of the left cerebral hemisphere and the brain activity levels of the right cerebral hemisphere becomes a negative value during a feedback period following the rest period; A correction unit that corrects the brain activity level of the left cerebral hemisphere and the brain activity level of the right cerebral hemisphere based on the baseline value during the feedback period; An index calculation unit that calculates a lateralization index with the result of subtracting the representative value of the brain activity level of the right cerebral hemisphere from the representative value of the brain activity level of the left cerebral hemisphere, or the result of subtracting the representative value of the brain activity level of the left cerebral hemisphere from the representative value of the brain activity level of the right cerebral hemisphere during the feedback period as the numerator, and the result of adding the representative value of the brain activity level of the left cerebral hemisphere and the representative value of the brain activity level of the right cerebral hemisphere as the denominator; An estimation unit that estimates the hemispheric dominance of the left cerebral hemisphere or the right cerebral hemisphere based on the lateralization index; A generation unit that generates sound or an image based on the estimated hemispheric dominance; A presentation unit that presents the generated sound or image to the subject A feedback system comprising the same.

2. The determination unit determines the baseline value based on the larger amplitude of the maximum amplitude of the brain activity level of the left cerebral hemisphere during the baseline determination period and the maximum amplitude of the brain activity level of the right cerebral hemisphere during the baseline determination period, and a weighting coefficient. The feedback system according to Claim 1.

3. The brain activity level of the left cerebral hemisphere is the brain activity level of the left prefrontal cortex, The brain activity level of the right cerebral hemisphere is the brain activity level of the right prefrontal cortex. The feedback system according to Claim 1.

4. The representative value is a moving average value or a moving median value. The feedback system according to Claim 1.

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