Neurofeedback system, neurofeedback method, control program, and recording medium

Abstract

A neurofeedback system (100) for achieving an effective NF system using SWRs comprises: a brain wave signal acquisition unit (11) that acquires a brain wave signal measured in a patient; and a feedback unit (an index calculation unit 12, an output control unit 14) that calculates an index related to a sharp wave ripple included in the acquired brain wave signal in real time and allows the patient to recognize the calculated index in real time.

Description

Neurofeedback system, neurofeedback method, control program, and recording medium

[0001] The present disclosure relates to neurofeedback systems.

[0002] In recent years, neurofeedback training techniques have been developed and proposed to guide a subject's state in a more favorable direction based on electroencephalogram (EEG) measurements of the subject. Neurofeedback training is expected to be effective in improving the subject's cognitive abilities and alleviating symptoms of mental illnesses (see Patent Document 1 and Non-Patent Document 1).

[0003] On the other hand, it has been elucidated that electroencephalograms with specific frequency characteristics are involved in various brain functions. For example, sharp wave ripple (SWR) waves with frequencies of 70 to 250 Hz frequently occur during immobile wakefulness and slow-wave sleep, and have been shown to be involved in various brain functions such as memory consolidation, temporal and spatial cognition, inferential thinking, and memory retrieval (see Non-Patent Documents 2 to 5).

[0004] US 2022 / 0322993

[0005] A. Belinskaia et al, "Short-delay neuralfeedback facilitates training of the parietal alpha rhythm," Journal of Neural Engineering, Volume 17, Number 6, 16 December 2020.H. Zhang et al, "Electrophysiological mechanisms of human memory consolidation," Nature communications, Volume 9, p4103, 2018.AP Vaz et al, "Replay of cortical spiking sequences during human memory retrieval," Science 367, p1131-1134, 2020.TK Leonard et al, "Sharp Wave Ripples during Visual Exploration in the Primate Hippocampus." Journal of Neuroscience, Volume 35, Number 44, p14771-14782, 2015.G. Girardeau et al, "Selective suppression of hippocampal ripples impairs spatial "Nature Neuroscience, Volume 12, Number 10, P1222-1223, 2009.

[0006] An object of one aspect of the present disclosure is to realize an effective neurofeedback system using SWR waves.

[0007] In order to solve the above problems, a neurofeedback system according to one embodiment of the present disclosure includes an EEG signal acquisition unit that acquires EEG signals measured from a subject, and a feedback unit that instantly calculates an index related to sharp wave ripple waves contained in the acquired EEG signals and makes the subject instantly aware of the calculated index.

[0008] Furthermore, a neurofeedback method according to one aspect of the present disclosure includes an electroencephalogram (EEG) signal acquisition step of acquiring an EEG signal measured from a subject, and a feedback step of instantly calculating an index related to sharp wave ripple waves contained in the acquired EEG signal and allowing the subject to instantly recognize the calculated index.

[0009] The neurofeedback system according to each aspect of the present disclosure may be realized by a computer. In this case, the control program for the neurofeedback system that causes the computer to operate as each part (software element) of the neurofeedback system and realizes the neurofeedback system on the computer, and the computer-readable recording medium on which the program is recorded, also fall within the scope of the present disclosure.

[0010] According to one aspect of the present disclosure, an effective NF system using SWR waves can be provided.

[0011] 1 is a block diagram showing an example configuration of a neurofeedback system according to one embodiment of the present disclosure;

[0023] FIG. 1 is a diagram showing an example of an electroencephalogram signal measured from the brain of a subject, and an example of a component between 70 Hz and 150 Hz extracted from the measured electroencephalogram signal;

[0024] FIG. 1 is a diagram showing an example of an SWR wave included in the electroencephalogram signal measured from the brain of a subject;

[0025] FIG. 2 is a diagram explaining an example of a method for making a subject recognize an index;

[0026] FIG. 3 is a flowchart showing an example of a processing flow executed by a neurofeedback system;

[0027] FIG. 4 is a diagram showing an example result when a subject is made to recognize the frequency of appearance of sharp wave ripple waves included in the electroencephalogram signal measured from the brain of the subject, and is instructed to control at least one of his or her own thoughts, emotions, and cognitive functions.

[0012] [Embodiment] (Neurofeedback System 100) A neurofeedback system 100 according to an embodiment of the present disclosure will be described in detail below with reference to FIG. 1. FIG. 1 is a block diagram showing an example configuration of the neurofeedback system 100. The neurofeedback system 100 is a system that enables neurofeedback training using sharp wave ripple waves (hereinafter referred to as SWR waves), which are known to be involved in various brain functions. The neurofeedback system 100 may include an information processing device 1 and an output device 3 that can present information output from the information processing device 1 to a subject T.

[0013] (Information Processing Device 1) First, the configuration of the information processing device 1 will be described with reference to Fig. 1. The information processing device 1 acquires an electroencephalogram signal measured from the subject T, instantly calculates an index related to sharp wave ripple waves (hereinafter referred to as SWR waves) contained in the electroencephalogram signal, and instantly presents output information corresponding to the calculated index on the output device 3. The information processing device 1 can instantly (for example, within 0.1 seconds) perform the following processes (1) to (3), thereby allowing the subject T to recognize the index related to the SWR waves contained in his or her own electroencephalogram signal.

[0014] (1) Extract SWR waves from the acquired EEG signal.

[0015] (2) Calculate the index for the extracted SWR wave.

[0016] (3) Present the output information on the output device 3.

[0017] As shown in FIG. 1 , the information processing device 1 includes a control unit 10 and a storage unit 20. The control unit 10 may be configured by a control device such as a CPU (central processing unit) or a processor. Each unit of the control unit 10 shown in FIG. 1 can be realized by a control device such as a CPU reading out a program stored in a storage unit 20 implemented by a ROM (read only memory) or the like into a RAM (random access memory) and executing the program. The control unit 10 includes at least an EEG signal acquisition unit 11, an index calculation unit 12 (feedback unit), and an output control unit 14 (feedback unit). The control unit 10 may further include an instruction unit 13.

[0018] The electroencephalogram signal acquiring unit 11 acquires electroencephalogram signals measured from the subject T. Fig. 1 shows an electrode E placed in the hippocampus of the brain of the subject T. The following describes an example in which the electroencephalogram signal acquiring unit 11 acquires electroencephalogram signals derived from the hippocampus, measured by the electrode E placed in the hippocampus of the brain of the subject T.

[0019] The EEG signal acquiring unit 11 may be configured to acquire EEG signals measured using electrodes E placed in the brain of the subject T. Alternatively, the EEG signals may be electrocorticogram (ECoG) signals measured using electrodes placed in the cortex of the brain of the subject T. Alternatively, the EEG signals may be scalp electroencephalograms (scalp EEG) or magnetoencephalograms (MEG), which are EEG signals measured non-invasively from the body surface of the subject T. In this case, the EEG signals of the subject T may be measured by electrodes arranged on a wearable device such as a headband or headgear, which contact the subject T's head, for example. The EEG signal acquiring unit 11 may be configured to store the acquired EEG signals as EEG signal data 21 in the storage unit 20.

[0020] The index calculation unit 12 includes an SWR extraction unit 121 that instantly extracts SWR waves contained in the EEG signal acquired by the EEG signal acquisition unit 11, and a calculation unit 122 that instantly calculates an index related to the extracted SWR waves.

[0021] The processing performed by the SWR extraction unit 121 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of an electroencephalogram signal measured from the brain of subject T (waveform A) and an example of a component of 70 Hz or more and 150 Hz or less contained in the measured electroencephalogram signal (waveform B).

[0022] Waveform A shown in Fig. 2 is unprocessed (raw) data of the EEG signal measured by electrode E. The SWR extraction unit 121 performs filtering on the EEG signal measured by electrode E to extract signals with frequencies between 70 Hz and 150 Hz. Waveform B shown in Fig. 2 is obtained by performing filtering on waveform A. After filtering, the SWR extraction unit 121 extracts (detects) SWR waves in waveform B. Note that Fig. 2 shows periods P1, P2, and P3 as periods during which SWR waves are detected. Fig. 3 is a diagram showing an example of an SWR wave (waveform C) extracted by the SWR extraction unit 121.

[0023] The calculation unit 122 instantly calculates an index related to the SWR waves contained in the EEG signal acquired by the EEG signal acquisition unit 11. Here, the index calculated by the calculation unit 122 may be at least one of the duration, signal strength (amplitude), and occurrence frequency of the SWR waves contained in the EEG signal. The duration of the SWR waves may be the length of time from the appearance to the disappearance of the SWR waves extracted by the SWR extraction unit 121. The occurrence frequency of the SWR waves may be, for example, the number of SWR waves detected per unit time (e.g., one second).

[0024] The output control unit 14 causes the output device 3 to output output information corresponding to the index calculated by the calculation unit 122, thereby allowing the subject T to instantly recognize the index.

[0025] The neurofeedback system 100 may output, to the subject T, who is being made to recognize the indicator (i.e., who is being presented with the output information), instruction voices, instruction messages, etc., instructing the subject T to control at least one of his / her thoughts, emotions, and cognitive functions. In this case, the control unit 10 may further include an instruction unit 13, as shown in FIG. 1 . The instruction unit 13 appropriately reads instruction voices, instruction messages, etc., for the subject T from instruction data 22 stored in the storage unit 20. The output control unit 14 may cause the output device 3 to output instruction voices, instruction messages, etc. By providing such instruction voices and instruction messages to the subject T, who is being made to recognize the indicators, it is possible to assist the subject T in controlling the intensity and frequency of SWR waves included in the EEG signal.

[0026] (Output Device 3) Next, the output device 3 will be described with reference to FIG. 1 . The output device 3 includes an index presenting unit 31. The index presenting unit 31 is capable of providing at least one of a sensory stimulus and an electrical stimulus in a manner corresponding to the index related to the SWR wave calculated by the information processing device 1 to the subject T in real time. This allows the neurofeedback system 100 to allow the subject T to instantly recognize output information corresponding to the index related to his or her own SWR wave. Here, the sensory stimulus may be at least one of a visual stimulus, a tactile stimulus, an olfactory stimulus, an auditory stimulus, and a gustatory stimulus.

[0027] For example, the output device 3 may be a display device, and in this case, the index presenting unit 31 can cause the subject T to recognize the index by presenting an image (output information) or the like in which the index related to SWR waves is visually represented. For example, the output device 3 may be a drive device that can apply a tactile stimulus to the body of the subject T, and in this case, the index presenting unit 31 can cause the subject T to recognize the index by presenting to the subject T a tactile stimulus of an intensity corresponding to the index related to SWR waves. For example, the output device 3 may be a device that emits an odor corresponding to the index related to SWR waves to the subject T, and in this case, the index presenting unit 31 can cause the subject T to recognize the index by presenting to the subject T an olfactory stimulus corresponding to the index related to SWR waves. For example, the output device 3 may be a device that emits a sound of a pitch or volume corresponding to the index related to SWR waves, and in this case, the index presenting unit 31 can cause the subject T to recognize the index by presenting to the subject T an auditory stimulus corresponding to the index related to SWR waves.

[0028] The output device 3 may include an instruction output unit 32 capable of outputting instruction sounds, instruction messages, etc. The instruction output unit 32 may be a display capable of displaying instruction messages, etc., or may be a speaker capable of outputting instruction sounds, etc.

[0029] 1, the output device 3 for causing the subject T to recognize the indices related to SWR waves also includes an instruction output unit 32, but the present invention is not limited to this configuration. For example, the neurofeedback system 100 may include a device (not shown) capable of outputting instruction voices and instruction messages to the subject T, separate from the output device 3 for causing the subject T to recognize the indices presented to the subject T. Instruction voices and instruction messages will be described later with specific examples.

[0030] <Example of Output Information> Here, an example of output information will be described using FIG. 4 . FIG. 4 is a diagram illustrating an example of a method for making a subject recognize the output information. As shown in FIG. 4 , when the occurrence frequency of SWR waves included in the EEG signal acquired from the subject T is low, the information processing device 1 causes the index presentation unit 31 of the output device 3 to display, for example, a small circle Q in real time, so that the subject T can visually recognize it (left side of FIG. 4 ). On the other hand, when the occurrence frequency of SWR waves included in the EEG signal acquired from the subject T is high, the information processing device 1 causes the index presentation unit 31 of the output device 3 to display, for example, a large circle Q in real time, so that the subject T can visually recognize it (right side of FIG. 4 ). In other words, the subject T can recognize an increase or decrease in the occurrence frequency of SWR waves included in his or her EEG signal as a change in the size of the circle Q displayed on the index presentation unit 31.

[0031] The information processing device 1 can make the subject T visually recognize such a circle within, for example, 0.1 seconds after acquiring the EEG signal from the subject T. That is, when the frequency of SWR waves included in the EEG signal of the subject T increases, the subject T visually recognizes a gradually increasing circle, and when the frequency of SWR waves included in the EEG signal of the subject T decreases, the subject T visually recognizes a gradually decreasing circle. In this way, the information processing device 1 can make the subject T immediately recognize fluctuations in the occurrence frequency (index) of SWR waves included in the EEG signal of the subject T.

[0032] (Processing Performed by Information Processing Device 1) First, the EEG signal acquiring unit 11 acquires an EEG signal measured from the subject T (S1: EEG signal acquiring step). Next, the index calculating unit 12 immediately calculates an index related to the SWR waves contained in the acquired EEG signal (S2: feedback step), and the output control unit 14 immediately makes the subject aware of the calculated index (S3: feedback step).

[0033] If the information processing device 1 is equipped with an instruction unit 13, the instruction unit 13 instructs the subject T, who has recognized the output information, to control at least one of his or her thoughts, emotions, and cognitive functions (S4: instruction process).

[0034] This configuration makes it possible to realize an effective neurofeedback system 100 that utilizes SWR waves contained in the electroencephalogram signal of the subject T. By appropriately selecting instructions to be given to the subject T, this neurofeedback system 100 can also be applied to improving the cognitive ability of the subject T and alleviating the symptoms of mental illness.

[0035] [Modification] In the neurofeedback system 100, the information processing device 1 may be configured to acquire EEG signals measured from multiple subjects T. For example, the multiple subjects T may be located in different medical facilities or rooms, and the EEG signals of the subjects T measured at each medical facility or room may be transmitted to the information processing device 1 from a communication device (not shown) installed in each medical facility or room. Here, the communication device may be, for example, a computer equipped with an output device 3 installed in each medical facility or room. In this case, the information processing device 1 may be connected to each communication device via a LAN. Alternatively, the information processing device 1 may be communicably connected via the Internet. That is, the information processing device 1 may be a device that applies cloud computing or a device installed within a specific medical facility.

[0036] According to this configuration, the information processing device 1 can instantly calculate an index related to the SWR waves contained in each of the EEG signals measured from multiple subjects T, and can output output information corresponding to the index calculated for each subject T to the output device 3.

[0037] [Example of implementation by software] The functions of the neurofeedback system 100 (hereinafter referred to as the "device") can be realized by a program that causes a computer to function as the system, and a program that causes a computer to function as each control block of the device (particularly each part included in the control unit 10 of the information processing device 1).

[0038] In this case, the system includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The functions described in each of the above embodiments are realized by executing the program using the control device and storage device.

[0039] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the system. In the latter case, the program may be supplied to the system via any wired or wireless transmission medium.

[0040] In addition, some or all of the functions of each of the control blocks can be realized by logic circuits. For example, integrated circuits in which logic circuits that function as each of the control blocks are formed are also included in the scope of the present disclosure. In addition, the functions of each of the control blocks can also be realized by, for example, a quantum computer.

[0041] Furthermore, each process described in each of the above embodiments may be executed by AI (Artificial Intelligence). In this case, the AI ​​may run on the control device or on another device (for example, an edge computer or a cloud server).

[0042] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0043] [Summary] The neurofeedback system according to aspect 1 of the present disclosure includes an electroencephalogram signal acquisition unit that acquires an electroencephalogram signal measured from a subject, and a feedback unit that instantly calculates an index related to sharp wave ripple waves contained in the acquired electroencephalogram signal and makes the subject instantly aware of the calculated index.

[0044] In a neurofeedback system according to aspect 2 of the present disclosure, in the above-mentioned aspect 1, the indicator may be at least one of the duration, signal strength, and frequency of occurrence of sharp wave ripple waves contained in the EEG signal.

[0045] The neurofeedback system according to aspect 3 of the present disclosure may further include an instruction unit instructing the subject, who has been made aware of the indicator, to control at least one of his or her own thoughts, emotions, and cognitive functions, in the above-mentioned aspect 1 or 2.

[0046] In a neurofeedback system according to aspect 4 of the present disclosure, in any one of aspects 1 to 3 above, the feedback unit may provide the subject with at least one of sensory stimulation and electrical stimulation in a manner corresponding to the indicator, thereby allowing the subject to instantly recognize the output information.

[0047] A neurofeedback system according to aspect 5 of the present disclosure is the same as that according to aspect 4 above, wherein the sensory stimulus may be at least one of a visual stimulus, a tactile stimulus, an olfactory stimulus, an auditory stimulus, and a gustatory stimulus.

[0048] A neurofeedback system according to a sixth aspect of the present disclosure is any one of the first to fifth aspects, wherein the electroencephalogram signal is an electroencephalogram signal derived from the hippocampus.

[0049] A neurofeedback system according to aspect 7 of the present disclosure, in any one of aspects 1 to 6 above, may be such that the electroencephalogram signal is an electroencephalogram signal measured non-invasively from the subject.

[0050] A neurofeedback system according to an eighth aspect of the present disclosure is any one of the first to seventh aspects, wherein the electroencephalogram signal is an electroencephalogram signal derived from the cortex.

[0051] A neurofeedback method according to aspect 9 of the present disclosure includes an electroencephalogram (EEG) signal acquisition step of acquiring an EEG signal measured from a subject, and a feedback step of instantly calculating an index related to sharp wave ripple waves contained in the acquired EEG signal and allowing the subject to instantly recognize the calculated index.

[0052] The neurofeedback method according to aspect 10 of the present disclosure may further include, in aspect 9 above, an instruction step of instructing the subject who has been made aware of the indicator to control at least one of his or her own thoughts, emotions, and cognitive functions.

[0053] A control program according to aspect 11 of the present disclosure is a control program for causing a computer to function as a neurofeedback system described in any one of aspects 1 to 8 above, and is a control program for causing a computer to function as the EEG signal acquisition unit and the feedback unit.

[0054] A recording medium according to aspect 12 of the present disclosure is a computer-readable recording medium on which the control program according to aspect 11 above is recorded.

[0055] An embodiment of the present disclosure is described below.

[0056] Electrodes were placed in the hippocampus of nine subjects, and EEG signals were acquired from each subject. The acquired EEG signals were filtered to selectively extract frequencies between 70 Hz and 150 Hz, and SWR waves contained in each subject's EEG signals were extracted. The subjects were then presented with output information (see Figure 4) corresponding to the frequency of the extracted SWR waves. Instructions 1 through 5 were given to the subjects, and we examined whether differences in the frequency of SWR waves occurred. Instruction 1: "Think freely." Instruction 2: "Try to relax and not think about anything as much as possible." Instruction 3: "Subtract sevens from 100." Instruction 4: "Read this book." Instruction 5: "Meditate." (Results) The frequency of SWR waves in the EEG signals of subjects instructed to do calculations (Instruction 3) and read (Instruction 4) was significantly lower than when instructed to think freely (Instruction 1). Conversely, the frequency of SWR waves in the EEG signals of subjects instructed to relax and not think about anything (instruction 2) was significantly higher than that of subjects instructed to think freely (instruction 1). The frequency of SWR waves in the EEG signals of subjects instructed to meditate (instruction 5) was the same as that of subjects instructed to think freely (instruction 1).

[0057] Thus, it was found that the SWR wave-related indicators (e.g., frequency of SWR waves) contained in one's own EEG signal change depending on the instructions given to the subject. It was also verified that an effective neurofeedback system can be constructed by having the subject recognize the SWR wave-related indicators contained in the EEG signal.

[0058] In the embodiment, the subject is given the instructions 1 to 5, but giving such instructions is not essential. For example, the subject may be configured to voluntarily control at least one of his / her own thoughts, emotions, and cognitive functions. In this case, the subject can learn how to control at least one of his / her own thoughts, emotions, and cognitive functions in order to change the index related to SWR waves contained in his / her EEG signal.

[0059] REFERENCE SIGNS LIST 1 Information processing device 3 Output device 11 Electroencephalogram signal acquisition unit 12 Index calculation unit (feedback unit) 13 Instruction unit 14 Output control unit (feedback unit) 100 Neurofeedback system S1 Electroencephalogram signal acquisition step S2, S3 Feedback step S4 Instruction step

Claims

1. A neurofeedback system comprising: an electroencephalogram signal acquisition unit that acquires electroencephalogram signals measured from a subject; and a feedback unit that instantly calculates an index related to sharp wave ripple waves contained in the acquired electroencephalogram signals and makes the subject instantly aware of the calculated index.

2. The neurofeedback system according to claim 1, wherein the index is at least one of the duration, signal strength, and occurrence frequency of sharp wave ripple waves contained in the electroencephalogram signal.

3. The neurofeedback system of claim 1, further comprising an instruction unit that instructs the subject, who is made aware of the indicator, to control at least one of his or her own thoughts, emotions, and cognitive functions.

4. A neurofeedback system as described in claim 1, wherein the feedback unit provides the subject with at least one of sensory stimulation and electrical stimulation in a manner corresponding to the indicator, thereby allowing the subject to instantly recognize the indicator.

5. The neurofeedback system according to claim 4, wherein the sensory stimulus is at least one of a visual stimulus, a tactile stimulus, an olfactory stimulus, an auditory stimulus, and a gustatory stimulus.

6. The neurofeedback system according to claim 1, wherein the electroencephalogram signal is an electroencephalogram signal derived from the hippocampus.

7. The neurofeedback system according to claim 1, wherein the electroencephalogram signal is an electroencephalogram signal measured non-invasively from the subject.

8. The neurofeedback system of claim 1, wherein the electroencephalographic signal is a cortical electroencephalographic signal.

9. A neurofeedback method comprising: an electroencephalogram signal acquisition step of acquiring an electroencephalogram signal measured from a subject; and a feedback step of instantly calculating an index related to sharp wave ripple waves contained in the acquired electroencephalogram signal and making the subject instantly recognize the calculated index.

10. The neurofeedback method according to claim 9, further comprising an instruction step of instructing the subject, who has been made aware of the indicator, to control at least one of his / her own thoughts, emotions, and cognitive functions.

11. A control program for causing a computer to function as the neurofeedback system according to claim 1, the control program causing a computer to function as the electroencephalogram signal acquisition section and the feedback section.

12. A computer-readable recording medium having the control program according to claim 11 recorded thereon.

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