Patent Description:
Neurofeedback training or the like aiming at estimation of a brain function with the use of functional magnetic resonance imaging (which will also be abbreviated as "fMRI" below) representing one of techniques for non-invasive measurement of a brain activity and modulation of the brain function has been known. The neurofeedback training only with fMRI faces a challenge in viability such as cost.

Then, a method of combining an electromagnetic field measurement method such as electroencephalogram (which will also be abbreviated as "EEG" below) and fMRI has been proposed (see, for example, PTL <NUM> or the like). Variation in signal (a time waveform) measured in EEG is herein collectively referred to as "brain waves.

With the technique disclosed in PTL <NUM> or the like, an estimation model is created from measurement data obtained by simultaneous EEG and fMRI in a resting state (which will also be abbreviated as "EEG/fMRI simultaneous measurement data" below), and based on the created estimation model, neurofeedback is given using only EEG measurement data. EEG is more advantageous than other measurement techniques in terms of portability, mobility, a price, and possibility of prevalence. Therefore, by adopting the technique disclosed in PTL <NUM> or the like, cost can be reduced to thereby enhance viability of neurofeedback training.

It has been proposed to estimate an activity of each brain network based on fMRI measurement data in a resting state and to estimate "disorder-likelihood" based on a brain function expressed in a plurality of brain networks (see NPL <NUM> or the like). Estimation of "disorder-likelihood" is expected to be applied to diagnosis of psychiatric disorders, identification of a subtype of an identical disorder, and selection of a therapy.

NPL6 discloses a computing system for seizure detection using invasive and noninvasive electrographic data. Seizure focus is localized and brain network connectivity is estimated using resting state functional magnetic resonance imaging (rs-fMRI) and EEG data analysis. A method for processing multimodal rs-fMRI and EEG big data for epileptogenic network definition and prediction of seizure (ictal) onset and a deep-learning approach to extract high order features for seizure detection and prediction in epilepsy is disclosed.

Conventional neurofeedback training is directed to change in activity in a specific brain region or a specific brain network (change in time correlation of activities between a plurality of brain regions) (see, NPL <NUM>).

A technique that allows easier estimation of any disorder associated with a plurality of brain networks has been demanded.

An estimation system according to one embodiment of the present invention includes obtaining means configured to obtain brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from a subject. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The estimation system includes first calculation means configured to calculate first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, second calculation means configured to calculate second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, third calculation means configured to calculate a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and machine learning means configured to determine an estimation model for estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label.

The estimation system may further include estimation means configured to estimate disorder-likelihood of the subject by inputting the brain wave measurement data measured from the subject into the estimation model.

The estimation system may further include presentation means configured to calculate a second score in accordance with the estimated disorder-likelihood of the subject and present to the subject, information in accordance with the calculated second score.

The estimation model may be prepared for each disorder. At this time, an estimation model corresponding to a disorder that manifests in the subject may be applied to the subject.

Change in symptom of the subject may be assessed based on a second score in accordance with the estimated disorder-likelihood of the subject.

The third calculation means may calculate the score representing the disorder-likelihood based on a sum of results of multiplication of the plurality of second functional connectivities brought in correspondence with disorder-likelihood to be estimated by respective corresponding weight parameters.

The third calculation means may calculate the disorder-likelihood label by normalizing the score representing the disorder-likelihood and subject the normalized score to threshold processing.

The estimation model may include information for selecting first functional connectivity to be used for estimation among first functional connectivities for each channel combination and a weight parameter brought in correspondence with the selected first functional connectivity.

The first calculation means may calculate the first functional connectivity from a correlation value between time waveforms in a section included in a window set in common for time waveforms of brain waves in two channels of interest.

The first calculation means may calculate the first functional connectivity for each frequency band included in the brain wave measurement data and/or for each window size of a set window.

The estimation system may further include condition setting means configured to determine in advance in accordance with the subject, the frequency band included in the brain wave measurement data to be inputted to the estimation model and/or the window size.

The second calculation means may calculate the second functional connectivity from a correlation value between time waveforms in a section included in a window set in common for time waveforms indicating amounts of activities in two regions of interest.

An estimation method according to another embodiment of the present invention includes obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from a subject. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The estimation method includes calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and determining an estimation model for estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label.

A program according to yet another embodiment of the present invention causes a computer to perform obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from a subject. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The program causes the computer to perform calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and determining an estimation model for estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label.

According to yet another embodiment of the present invention, a trained estimation model for estimating disorder-likelihood of a subject based on brain wave measurement data measured from the subject is provided. Processing for constructing the estimation model includes obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from the subject. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. Processing for constructing the estimation model includes calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and determining the estimation model by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label.

According to yet another embodiment of the present invention, a brain activity training apparatus for conducting neurofeedback training is provided. The brain activity training apparatus includes a storage device where an estimation model for estimating disorder-likelihood of a subject generated before the neurofeedback training is conducted is stored and an electroencephalograph configured to measure brain wave measurement data of the subject in the neurofeedback training. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The brain activity training apparatus includes a presentation apparatus and a processing apparatus configured to calculate, in the neurofeedback training, disorder-likelihood of the subject with the estimation model based on measurement data from the electroencephalograph and outputs a signal for representation corresponding to the disorder-likelihood to the presentation apparatus.

The estimation model is generated by processing for obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from the subject, processing for calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, processing for calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, processing for calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and processing for determining the estimation model by estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label. The simultaneously measured brain wave measurement data includes a time waveform for each channel corresponding to each channel of the brain wave measurement data measured in the neurofeedback training.

According to yet another embodiment of the present invention, a brain activity training method for conducting neurofeedback training is provided. The brain activity training method includes obtaining an estimation model for estimating disorder-likelihood of a subject generated before the neurofeedback training is conducted and measuring brain wave measurement data of the subject in the neurofeedback training. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The brain activity training method includes calculating, in the neurofeedback training, disorder-likelihood of the subject with the estimation model based on the brain wave measurement data and outputting a signal for representation corresponding to the disorder-likelihood to a presentation apparatus. The obtaining an estimation model includes processing for obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from the subject, calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and determining the estimation model by estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label. The simultaneously measured brain wave measurement data includes a time waveform for each channel corresponding to each channel of the brain wave measurement data measured in the neurofeedback training.

According to yet another embodiment of the present invention, a brain activity training program for conducting neurofeedback training is provided. The brain activity training program causes a computer to perform storing an estimation model for estimating disorder-likelihood of a subject generated before the neurofeedback training is conducted and obtaining brain wave measurement data of the subject in the neurofeedback training. The brain wave measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of the subject. The brain activity training program causes the computer to perform calculating, in the neurofeedback training, disorder-likelihood of the subject with the estimation model based on the brain wave measurement data and outputting a signal for representation corresponding to the disorder-likelihood to a presentation apparatus. The estimation model is generated by processing for obtaining brain wave measurement data and functional magnetic resonance imaging measurement data simultaneously measured from the subject, processing for calculating first functional connectivity for each channel combination based on correlation between channels included in the brain wave measurement data, processing for calculating second functional connectivity for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data, processing for calculating a disorder-likelihood label by calculating a score representing disorder-likelihood to be estimated based on a plurality of second functional connectivities, and processing for determining the estimation model by estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label. The simultaneously measured brain wave measurement data includes a time waveform for each channel corresponding to each channel of the brain wave measurement data measured in the neurofeedback training.

According to one embodiment of the present invention, any disorder associated with a plurality of brain networks can more easily be estimated.

An embodiment of the present invention will be described in detail with reference to the drawings. The same or corresponding elements in the drawings have the same reference characters allotted and description thereof will not be repeated.

Overview of an estimation method according to the present embodiment will initially be described. <FIG> and <FIG> are schematic diagrams showing overview of the estimation method according to the present embodiment. <FIG> shows overview of processing (a learning phase) for determining an estimation model and <FIG> shows overview of processing (an estimation phase) for estimating disorder-likelihood with the determined estimation model.

The "disorder" herein is a term that encompasses not only sick symptoms of humans but also any mental or physical symptoms different from a condition that manifests in standard persons. A symptom that manifests in this case is also referred to as a "disorder-like symptom. " "Disorder-likelihood" is a term that encompasses possibility (probability) that a subject of interest has a symptom corresponding to a "disorder" of interest and possibility (probability) that a symptom corresponding to a "disorder" of interest manifests in a subject of interest.

An "estimation model" herein is not limited to an estimation model to be used for estimation of such possibility, and it may also be used for estimation of possibility that a healthy person is in a state of a brain activity different by a prescribed extent or more from a standard "healthy brain activity state" (an extent of difference). In other words, the estimation model may also be used for estimation of a relative state of a brain activity.

"Functional connectivity" herein is a term that encompasses an indicator indicating a degree of functional connection between regions in the brain. The "functional connectivity" can be calculated with any method based on data measured with any measurement method. The method of calculating "functional connectivity" herein is not limited except for a case where specific measurement data and a specific calculation method are specified.

Referring to <FIG>, in the estimation method in the present embodiment, initially, the same subject is simultaneously subjected to EEG and fMRI in a resting state to obtain EEG/fMRI simultaneous measurement data ((<NUM>) EEG/fMRI simultaneous measurement). At this time, data obtained by EEG (which will also be referred to as "EEG measurement data" below) and data obtained by fMRI (which will also be referred to as "fMRI measurement data" below) represent the same brain activities of the same subject. In other words, EEG/fMRI simultaneous measurement data includes brain wave measurement data (EEG measurement data) and measurement data of functional magnetic resonance imaging (fMRI measurement data) measured simultaneously from a subject.

Each sensor is typically composed of a pair of electrodes. Each sensor is also referred to as a channel and EEG measurement data corresponds to multiple-channel brain waves. In other words, EEG measurement data includes time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of a subject. Functional connectivity in each frequency band is calculated from EEG measurement data ((<NUM>) calculate functional connectivity (FC)). The functional connectivity is also referred to as "FC" below.

In the estimation method according to the present embodiment, not only EEG representing a value of measurement of a voltage generated by electrical activities of a brain but also magnetoencephalography (MEG) representing a value of measurement of time-varying magnetic field generated by electrical activities of the brain can be used. For the sake of convenience of description, an example in which EEG measurement data is used will mainly be described in the description below.

fMRI measurement data is used for estimation of disorder-likelihood of a subject from a specific brain network. The brain network is also referred to as a resting state network (RSN), and it is a generic denotation of a characteristic brain activity pattern originating from a signal source belonging to a single brain region or coordination of signal sources belonging to a plurality of spatially distant brain regions. The brain network is defined mainly by fMRI in the resting state.

Specifically, seven types of (<NUM>) a control network (CON), (<NUM>) a dorsal attention network (DAN), (<NUM>) a default mode network (DMN), (<NUM>) a limbic system (LIM), (<NUM>) a somatomotor network (SMN), (<NUM>) a ventral attention network (VAN), and (<NUM>) a visual network (VIS) have been known as the resting state networks.

The (<NUM>) control network (CON) may also be referred to as a frontal parietal network and the (<NUM>) ventral attention network (VAN) may also be referred to as a saliency network.

The resting state network described above may further be divided into some subnetworks. More specifically, the (<NUM>) control network (CON) is divided into three subnetworks, the (<NUM>) default mode network (DMN) is divided into four subnetworks, and each of other networks is divided into two subnetworks.

Disorder-likelihood of a subject is considered as being estimated based on one or more specific brain networks that have been known in advance for each disorder. Therefore, in the estimation method according to the present embodiment, disorder-likelihood of a subject is estimated based on one or more specific brain networks ((<NUM>) estimate disorder-likelihood based on a plurality of brain networks). In the description below, a result of threshold processing (by way of example, binarization processing) of disorder-likelihood is outputted. Therefore, a result of estimation is also referred to as a "disorder-likelihood label" (label). The disorder-likelihood label takes any of a plurality of values (labels).

Finally, an estimation model for estimating disorder-likelihood of a subject is determined by inputting EEG measurement data based on dynamic functional connectivity in each frequency band and disorder-likelihood of the subject ((<NUM>) determine estimation model). The estimation model corresponds to a kind of a trained model.

Referring to <FIG>, EEG measurement data measured by EEG from a subject is inputted to a determined estimation model <NUM>, so that a result of estimation of disorder-likelihood of the subject is outputted. With the result of estimation of disorder-likelihood of the subject, neurofeedback training (which will also simply be referred to as "training" below) or the like can be conducted. As will be described later, estimation model <NUM> includes also a function to select information suitable for estimation of disorder-likelihood from EEG measurement data measured by EEG from the subject.

Since a state of disorder-likelihood of the subject can successively be estimated with such estimation model <NUM>, for example, neurofeedback can be realized with low cost. As will be described later, the estimation model has specificity depending on target thereof. Therefore, the estimation model is prepared for each disorder. Then, the estimation model corresponding to a disorder that manifests in a subject is applied.

An exemplary hardware configuration of an estimation system for realizing the estimation method according to the present embodiment will now be described.

<FIG> is a schematic diagram showing an exemplary hardware configuration of estimation system <NUM> that estimates disorder-likelihood according to the present embodiment. Referring to <FIG>, estimation system <NUM> includes a processing apparatus <NUM>, an EEG apparatus <NUM>, and an fMRI apparatus <NUM>.

Processing apparatus <NUM> obtains brain wave measurement data (EEG measurement data) and measurement data (fMRI measurement data) of functional magnetic resonance imaging that are simultaneously measured from a subject. More specifically, processing apparatus <NUM> accepts EEG measurement data measured by EEG apparatus <NUM> and fMRI measurement data measured by fMRI apparatus <NUM> and determines an estimation model for estimating disorder-likelihood.

EEG apparatus <NUM> detects a signal (an electrical signal) representing brain waves generated in a plurality of sensors <NUM> arranged on the head of a subject S. EEG apparatus <NUM> includes a multiplexer <NUM>, a noise filter <NUM>, an analog to digital (A/D) converter <NUM>, a storage <NUM>, and an interface <NUM>.

Multiplexer <NUM> sequentially selects one set of cables from among cables <NUM> connected to the plurality of sensors <NUM> and electrically connects the set of cables to noise filter <NUM>. Noise filter <NUM> is a filter which removes noise, such as a high-frequency cut filter, and removes noise components contained in a signal (an electrical signal) representing brain waves generated in the set of cables corresponding to a selected channel.

A/D converter <NUM> samples an electrical signal (an analog signal) outputted from noise filter <NUM> every prescribed cycle and outputs the signal as a digital signal. Storage <NUM> successively stores chronological data (digital signals) outputted from A/D converter <NUM> in association with information representing a selected channel and timing (for example, time or a counter value).

Interface <NUM> outputs chronological data representing brain waves that is stored in storage <NUM> to processing apparatus <NUM> in response to an access from processing apparatus <NUM> or the like.

fMRI apparatus <NUM> measures brain activities by detecting electromagnetic waves generated by resonance from a specific nucleus (for example, a hydrogen nucleus) by applying high-frequency electromagnetic field at a resonant frequency to a region from which information on brain activities of subject S is to be obtained (which will also be referred to as a "region of interest" below).

fMRI apparatus <NUM> includes a magnetic field application mechanism <NUM>, a reception coil <NUM>, a driver <NUM>, and a data processing unit <NUM>.

Magnetic field application mechanism <NUM> applies controlled magnetic field (static magnetic field and gradient magnetic field) to a region of interest of subject S and emits radio frequency (RF) pulses thereto. More specifically, magnetic field application mechanism <NUM> includes a static magnetic field generation coil <NUM>, a gradient magnetic field generation coil <NUM>, an RF emitter <NUM>, and a bed <NUM> including a bore in which subject S lies.

Driver <NUM> is connected to magnetic field application mechanism <NUM>, and controls magnetic field applied to subject S and transmission and reception of RF pulse waves. More specifically, driver <NUM> includes a static magnetic field power supply <NUM>, a gradient magnetic field power supply <NUM>, a signal transmitter <NUM>, a signal receiver <NUM>, and a bed driver <NUM>.

In <FIG> a central axis of a cylindrical bore in which subject S lies is defined as a Z axis and a horizontal direction and a vertical direction orthogonal to the Z axis are defined as an X axis and a Y axis, respectively.

Static magnetic field generation coil <NUM> generates static magnetic field in a Z-axis direction in the bore from a helical coil wound around the Z axis. Gradient magnetic field generation coil <NUM> includes an X coil, a Y coil, and a Z coil (none of which are shown) which generate gradient magnetic field in an X-axis direction, a Y-axis direction, and the Z-axis direction in the bore. RF emitter <NUM> emits RF pulses to a region of interest in subject S based on a high-frequency signal transmitted from signal transmitter <NUM> in accordance with a control sequence. Though <FIG> shows an exemplary configuration in which RF emitter <NUM> is contained in magnetic field application mechanism <NUM>, RF emitter <NUM> may be provided on a side of bed <NUM>, or RF emitter <NUM> and reception coil <NUM> may be integrated with each other.

Reception coil <NUM> receives electromagnetic waves (NMR signals) emitted from subject S and outputs an analog signal. The analog signal outputted from reception coil <NUM> is subjected to amplification and A/D conversion in signal receiver <NUM> and then output to data processing unit <NUM>. Reception coil <NUM> is preferably arranged in proximity to subject S such that an NMR signal can be detected at high sensitivity.

Data processing unit <NUM> sets a control sequence for driver <NUM> and outputs a plurality of brain activity pattern images representing an activation factor of the brain as information representing brain activities, based on the NMR signal received by reception coil <NUM>.

Data processing unit <NUM> includes a control unit <NUM>, an input unit <NUM>, a display unit <NUM>, a storage <NUM>, a representation controller <NUM>, an image processing unit <NUM>, a data collector <NUM>, and an interface <NUM>. Data processing unit <NUM> may be implemented by a dedicated computer or a general-purpose computer which performs prescribed processing by executing a control program stored in storage <NUM> or the like.

Control unit <NUM> controls an operation by each functional unit, such as generation of a control sequence for driving driver <NUM>. Input unit <NUM> accepts various operations or information input from a not-shown operator. Display unit <NUM> has various images and various types of information relating to a region of interest in subject S shown on a screen. Storage <NUM> stores a control program for performing processing involved with fMRI, a parameter, image data (a three-dimensional model image or the like), and other electronic data. Image processing unit <NUM> generates a plurality of brain activity pattern images based on data of a detected NMR signal. Interface <NUM> exchanges various signals with driver <NUM>. Data collector <NUM> collects data constituted of a set of NMR signals derived from a region of interest.

<FIG> is a schematic diagram showing an exemplary hardware configuration of processing apparatus <NUM> included in estimation system <NUM> that performs the estimation method according to the present embodiment. A computer in accordance with a general-purpose architecture can typically be adopted as processing apparatus <NUM>. Referring to <FIG>, processing apparatus <NUM> includes as its main components, a processor <NUM>, a main storage <NUM>, a control interface <NUM>, a network interface <NUM>, an input unit <NUM>, a display unit <NUM>, and a secondary storage <NUM>.

Processor <NUM> is implemented by an operation processing circuit such as a central processing unit (CPU) or a graphical processing unit (GPU), and performs various functions which will be described later by executing codes included in various programs stored in secondary storage <NUM> in a designated order. Main storage <NUM> is implemented by a dynamic random access memory (DRAM) or the like and holds a code of a program executed by processor <NUM> or various types of work data necessary for execution of a program.

Processing apparatus <NUM> has a communication function, which is provided mainly by control interface <NUM> and network interface <NUM>.

Control interface <NUM> exchanges data with data processing unit <NUM> of fMRI apparatus <NUM>. Network interface <NUM> exchanges data with an external apparatus (for example, a data server apparatus on the cloud). Control interface <NUM> and network interface <NUM> are implemented by any communication component such as a wired local area network (LAN), a wireless LAN, a universal serial bus (USB), or Bluetooth®.

Input unit <NUM> is typically implemented by a mouse, a keyboard, or the like and accepts an operation by a user. Display unit <NUM> is typically implemented by a display and notifies a user of various types of information involved with a state of processing performed in processing apparatus <NUM> or an operation.

Secondary storage <NUM> is typically implemented by a hard disk or a solid state drive (SSD) and holds various programs executed by processor <NUM>, various types of data necessary for processing, and a set value. More specifically, secondary storage <NUM> stores EEG measurement data <NUM>, fMRI measurement data <NUM>, an estimation model determination program <NUM>, an estimation program <NUM>, and an estimation model parameter <NUM>.

Processing for determining an estimation model in the estimation method according to the present embodiment will now be described.

<FIG> is a diagram for illustrating processing for determining an estimation model in the estimation method according to the present embodiment. <FIG> is a diagram showing exemplary data processing for determining an estimation model in the estimation method according to the present embodiment.

Processing for calculating FC which is an explanatory variable is performed on EEG measurement data <NUM> included in EEG/fMRI simultaneous measurement data and processing for calculating a disorder-likelihood label which is an explained variable is performed on fMRI measurement data <NUM> included in EEG/fMRI simultaneous measurement data. Such processing will be described with reference to <FIG> and <FIG>.

EEG measurement data <NUM> is a collection of variations in signal (time waveforms) representing brain waves measured for each channel (sensor). EEG measurement data <NUM> is converted to a time waveform <NUM> of power for each frequency band by preprocessing (corresponding to (<NUM>) preprocessing in <FIG>). Time waveform <NUM> of power means successive calculation for each unit time, of an average value of square values of amplitudes of corresponding frequency components included in EEG measurement data <NUM>.

More specifically, in preprocessing, EEG measurement data <NUM> (time waveform) is subjected to frequency conversion to calculate an amplitude for each frequency. Then, one frequency or a plurality of frequencies included in a designated frequency band is/are selected, the amplitude(s) of the one selected frequency or the plurality of selected frequencies is/are squared, and an average value of the amplitude(s) is calculated. Power can thus be calculated.

When a sampling frequency of EEG measurement data <NUM> is high, down sampling to a prescribed sampling frequency may be performed and then frequency analysis may be conducted. For example, down sampling may be performed such that the sampling frequency is set to <NUM>/TR [Hz] so as to correspond to an emission cycle (repetition time (TR)) of RF pulses in fMRI.

EEG measurement data <NUM> is thus preprocessed to generate time waveform <NUM> of power of N channels × M frequency bands. Examples of the frequency band include theta waves (θ waves: <NUM> to <NUM>), alpha waves (α waves: <NUM> to <NUM>), low beta waves (low β waves: <NUM> to <NUM>), and high beta waves (high β waves: <NUM> to <NUM>). For example, when the number of channels N is set to <NUM> and the number of frequency bands M is set to <NUM>, <NUM> (= <NUM> × <NUM>) time waveforms of power are generated.

Then, time correlation of time waveforms <NUM> of power between different channels for the same frequency band is calculated (corresponding to ((<NUM>) calculation of time correlation in <FIG>).

"Time correlation" herein means a correlation value between time waveforms and a time waveform of a correlation value in a section included in a window <NUM> set in common for a plurality of time waveforms.

For EEG measurement data <NUM>, time correlation between two time waveforms <NUM> of power is calculated. At this time, the time correlation means a time waveform of a correlation value with attention being paid to a temporal width of window <NUM> set for two time waveforms <NUM> of power. In other words, functional connectivity (FC) is calculated from the correlation value between time waveforms in the section included in window <NUM> set in common for time waveforms of brain waves in two channels of interest.

Window <NUM> has a prescribed window size (temporal width). A time waveform <NUM> of EEG time correlation can be calculated by sequentially shifting, by each step size, a setting position where window <NUM> is set (a temporal section from start time until end time) and by sequentially calculating correlation corresponding to each setting position of window <NUM>. Calculated time waveform <NUM> of EEG time correlation corresponds to the FC.

Functional connectivity (FC) is thus calculated for each channel combination (each channel pair) based on correlation between channels included in EEG measurement data <NUM>.

For example, when the number of channels N in EEG is set to <NUM>, time waveform <NUM> of EEG time correlation can be calculated for each of <NUM> (= N×(N-<NUM>)/<NUM> = <NUM>×(<NUM>-<NUM>)/<NUM>) channel combinations (channel pairs). Time waveform <NUM> of EEG time correlation has a time length corresponding to the number of times of shifting (the number of time steps) of window <NUM>.

Time waveform <NUM> of EEG time correlation is calculated for each frequency band. In other words, time waveforms <NUM> of EEG time correlation for M frequency bands are generated.

Furthermore, with the window size (temporal width) of set window <NUM> being varied, time waveform <NUM> of EEG time correlation may be calculated for each of the windows.

Thus, time waveform <NUM> of EEG time correlation with three items of the channel pair, the frequency band, and the window size being varied may be employed as a feature value for estimating disorder-likelihood. In this case, time waveform <NUM> of EEG time correlation is outputted as a vector of channel combination (channel pair) dimensions × (the number of time steps corresponding to window <NUM>) dimensions for each frequency band and/or for each window size.

Functional connectivity (FC) may thus be calculated for each frequency band included in EEG measurement data <NUM> and/or for each window size of set window <NUM>.

A single vector for all frequency bands and all window sizes as being integrated may be generated. In this case, a vector of {(the number of channel combinations (channel pairs)) × (the number of window sizes) × (the number of frequency bands)} dimensions × (the number of time steps) dimensions is outputted. In other words, in the example described above, a vector of <NUM> dimensions × (the number of time steps) dimensions may be outputted for each frequency band and/or for each window size, or a vector of more dimensions resulting from integration of the above may be outputted.

fMRI measurement data <NUM> (that is, a brain activity pattern image) is an assembly of brain activity pattern images obtained for each emission cycle of RF pulses. It has already been known, to a brain activity in which region in the brain each of already known brain networks (resting state networks) corresponds. One region or a plurality of regions corresponding to each of such brain networks correspond(s) to region(s) of interest (which will also be abbreviated as an "ROI" below).

In the estimation method according to the present embodiment, an activity of each brain network is assumed to be defined by a combination of two ROIs.

Initially, fMRI measurement data <NUM> is subjected to preprocessing (corresponding to (<NUM>') preprocessing in <FIG>) to calculate a BOLD signal <NUM> for each ROI. The BOLD signal means change over time in amount of activity dependent on a blood oxygen level for each ROI. More specifically, in preprocessing on fMRI measurement data <NUM>, the BOLD signal is calculated based on an image feature value corresponding to the ROI included in a brain activity pattern image.

Then, time correlation of BOLD signal <NUM> between corresponding ROIs is calculated for each brain network (corresponding to (<NUM>') calculation of time correlation in <FIG>). For fMRI measurement data <NUM>, time correlation between two BOLD signals <NUM> is calculated. At this time, time correlation means a time waveform of a correlation value with attention being paid to a temporal width of window <NUM> set for two BOLD signals <NUM>. In other words, functional connectivity (FC') is calculated from the correlation value between time waveforms in a section included in window <NUM> set in common for time waveforms representing the amounts of activity in two ROIs of interest.

Window <NUM> has a prescribed window size (temporal width). A time waveform <NUM> of BOLD time correlation can be calculated by sequentially shifting, by each step size, a setting position where window <NUM> is set (a temporal section from start time until end time) and by sequentially calculating correlation corresponding to each setting position of window <NUM>. Time waveform <NUM> of BOLD time correlation represents change over time in correlation value and corresponds to functional connectivity (FC').

Time waveform <NUM> of BOLD time correlation can be calculated for each ROI combination, that is, for each brain network of interest. The functional connectivity (FC') is calculated for each brain network based on correlation between ROIs included in fMRI measurement data <NUM>.

"Dynamic" in <FIG> means that a value is calculated for each window to which attention is paid, and "Static" means that a single value is calculated throughout a period. Therefore, "Static FC" in <FIG> means a correlation value over the entire period (single functional connectivity).

Disorder-likelihood is estimated based on thus calculated time waveform <NUM> (FC') of BOLD time correlation (corresponding to (<NUM>') estimation of disorder-likelihood in <FIG>). It has been known from prior studies that disorder-likelihood is associated with a plurality of brain networks (that is, brain activities in a plurality of ROIs).

In the estimation method according to the present embodiment, with such advance information, WLS <NUM> which is a score representing disorder-likelihood to be estimated is calculated based on time waveforms <NUM> of BOLD time correlations corresponding to a plurality of brain networks associated with disorder-likelihood to be estimated. More specifically, WLS <NUM> is calculated by multiplying time waveforms <NUM> (FC') of a plurality of BOLD time correlations of interest by respective corresponding weight parameters and adding results of multiplication. Such a calculation method has been known as weighted linear summation (WLS).

WLS <NUM> which is a score representing disorder-likelihood is calculated based on the sum of results of multiplication of a plurality of functional connectivities (time waveforms <NUM> of BOLD time correlations) brought in correspondence with disorder-likelihood to be estimated by respective corresponding weight parameters.

A disorder-likelihood label <NUM> is calculated by thus calculating a score (WLS <NUM>) representing disorder-likelihood to be estimated with the use of a plurality of time waveforms <NUM> (FC') of BOLD time correlations.

Furthermore, disorder-likelihood label <NUM> (label) is calculated by normalizing the score (WLS <NUM>) representing disorder-likelihood and then subjecting the normalized score to threshold processing. When binarization processing is adopted as the threshold processing, disorder-likelihood label <NUM> is set to "<NUM>" meaning being healthy or "<NUM>" meaning disorder.

Disorder-likelihood label <NUM> is outputted as a vector of one dimension × (the number of set windows <NUM>) dimension(s) that expresses disorder-likelihood to be estimated. Disorder-likelihood label <NUM> is handled as an explained variable.

The estimation model defines relation between time waveform <NUM> (FC) of EEG time correlation which is an explanatory variable and disorder-likelihood label <NUM> (label) which is an explained variable. In the estimation method according to the present embodiment, a feature value suitable for estimation of disorder-likelihood label <NUM> among feature values included in time waveform <NUM> of EEG time correlation which is expressed as a multi-dimensional vector is selected. In the estimation phase, disorder-likelihood is estimated based on information on the selected feature value (sequentially calculated time correlation). In other words, an estimation model for estimating disorder-likelihood is determined based on time waveform <NUM> (FC) of prescribed EEG time correlation by machine learning using time waveform <NUM> (FC) of EEG time correlation for each channel combination (for each channel pair) and disorder-likelihood label <NUM>.

By thus making use only of at least one of feature values included in time waveform <NUM> of EEG time correlation which is an explanatory variable for estimation, dimensions can be compressed and reduced, so that an amount of computation involved with estimation can be reduced and estimation processing can be faster.

Though any machine learning algorithm can be employed for determination of the estimation model, by way of example, sparse logistic regression (SLR) may be adopted.

Specifically, time waveform <NUM> of EEG time correlation is inputted as an explanatory variable to the SLR which is a machine learning algorithm (corresponding to (<NUM>) input to SLR in <FIG>) and disorder-likelihood label <NUM> is inputted as an explained variable to the SLR which is the machine learning algorithm (corresponding to (<NUM>') input to SLR in <FIG>). Then, a feature value suitable for estimation of disorder-likelihood label <NUM> is selected by machine learning.

<FIG> is a diagram for illustrating overview of an estimation model determined in the estimation method according to the present embodiment. Referring to <FIG>, time waveform <NUM> of EEG time correlation exhibits a group of feature values in accordance with the number of channels in EEG for each frequency band. Though not shown, time waveform <NUM> of EEG time correlation is calculated also for each window size.

A prescribed number of (for example, thirty) feature values Fi (i = <NUM>, <NUM>,. , x) suitable for estimation of disorder-likelihood label <NUM> among a large number of feature values that constitute a multi-dimensional vector of time waveform <NUM> of EEG time correlation are selected by machine learning.

Furthermore, a weight parameter Wi (i = <NUM>, <NUM>,. , x) may be determined for each of selected feature values. For example, a larger value of weight parameter Wi may be set for feature value Fi more suitable for estimation of disorder-likelihood label <NUM>.

Alternatively, instead of a technique to select a feature value and determine weight parameter Wi corresponding to selected feature value Fi, only weight parameter Wi may be determined. For example, by setting weight parameter Wi to zero for a feature value not used for estimation of disorder-likelihood label <NUM>, a result as in an example where a feature value is not selected can be obtained.

Thus, the determined estimation model includes information for selecting time waveform <NUM> (feature value Fi) of EEG time correlation to be used for estimation among time waveforms <NUM> (FC) of EEG time correlation for each channel combination (for each channel pair) and weight parameter Wi brought in correspondence with selected time waveform <NUM> of EEG time correlation.

In the estimation phase, disorder-likelihood of a subject is sequentially estimated only based on EEG measurement data <NUM> with the use of the feature value and the corresponding weight parameter determined in a procedure as described above.

<FIG> is a flowchart showing a processing procedure in the estimation method according to the present embodiment. Some steps shown in <FIG> may be performed by execution of a program in processing apparatus <NUM>.

Referring to <FIG>, initially, EEG measurement data <NUM> and fMRI measurement data <NUM> are obtained by simultaneous measurement of EEG and fMRI (step S100). In other words, processing apparatus <NUM> obtains measurement data (EEG measurement data <NUM>) of brain waves and measurement data (fMRI measurement data <NUM>) of fMRI simultaneously measured from a subject.

Processing apparatus <NUM> preprocesses obtained EEG measurement data <NUM> to calculate a time waveform of power for each frequency band (step S102). Then, processing apparatus <NUM> calculates a time waveform of EEG time correlation for each window size based on the calculated time waveform of power (step S104). In other words, processing apparatus <NUM> calculates functional connectivity (FC) for each channel combination based on correlation between channels included in EEG measurement data <NUM>.

In parallel to processing in steps S102 and S104 or after step S104, processing apparatus <NUM> preprocesses obtained fMRI measurement data <NUM> to calculate a time waveform of a BOLD signal for each ROI that composes a brain network (step S112). Then, processing apparatus <NUM> calculates a time waveform of BOLD time correlation for each window size based on the calculated time waveform of the BOLD signal (step S114). In other words, processing apparatus <NUM> calculates functional connectivity (FC') for each brain network based on correlation between ROIs included in fMRI measurement data <NUM>.

Then, processing apparatus <NUM> selects a time waveform of BOLD time correlation in accordance with disorder-likelihood to be estimated among calculated time waveforms of BOLD time correlations, multiplies the time waveform with each corresponding weight parameter, and adds results of multiplication to calculate WLS (step S116). Then, processing apparatus <NUM> calculates the disorder-likelihood label representing disorder-likelihood by normalizing the calculated WLS and then binarizing the normalized WLS (step S118). In other words, processing apparatus <NUM> calculates the disorder-likelihood label by calculating a score (WLS) representing disorder-likelihood to be estimated based on a plurality of functional connectivities (FC').

Finally, processing apparatus <NUM> determines the feature value and the weight parameter for estimating the disorder-likelihood label by machine learning using the time waveform of EEG time correlation and the disorder-likelihood label (step S120). In other words, processing apparatus <NUM> determines the estimation model for estimating disorder-likelihood based on the prescribed functional connectivity (FC) by machine learning using the functional connectivity (FC) and the disorder-likelihood label for each channel combination.

The estimation model can be determined through such a procedure.

Processing apparatus <NUM> stores measurement data from EEG apparatus <NUM> and fMRI apparatus <NUM> in correspondence with each other, with common time being defined as the reference. EEG measurement data <NUM> and fMRI measurement data <NUM> common in time axis can be obtained based on correspondence of measurement data based on such common time.

"(<NUM>) Calculate functional connectivity (FC)" shown in <FIG> and steps S102 to S104 shown in <FIG> will now be described in detail.

As preprocessing on EEG measurement data <NUM> (time waveform), initially, a time waveform is subjected to frequency conversion. For example, fast Fourier transform or the like can be employed as processing for frequency conversion. Without being limited to fast Fourier transform, Hilbert transform or discrete Fourier transform may be employed.

For preprocessing in step S102 in <FIG>, by frequency conversion of EEG measurement data <NUM>, data on a frequency domain (relation between a frequency and an amplitude) is calculated. By calculating for each frequency band of interest, an average value of square values of amplitudes of frequencies included in the frequency band, power of the frequency band is calculated.

In step S104 in <FIG>, any two channels are selected and the window is sequentially shifted along a time axis, so that a correlation value between time waveforms of power within the window is sequentially calculated.

Through such processing, time waveform <NUM> (FC) of EEG time correlation can be calculated.

<FIG> is a flowchart showing a more detailed processing procedure in steps S102 and S104 in <FIG>. Referring to <FIG>, processing apparatus <NUM> selects one channel included in obtained EEG measurement data <NUM> (step S1021), selects time of interest of calculation of power (step S1022), and subjects a time waveform included in the window with the selected time being defined as a reference position to fast Fourier transform (step S1023).

The time waveform included in the window may be subjected to moving average along the time axis and then to fast Fourier transform. By application of such moving average, a noise component at a high frequency can be reduced.

Then, processing apparatus <NUM> selects a frequency band of interest of calculation of power (step S1024) and calculates an average value of square values of amplitudes of frequencies included in the selected frequency band (step S1025). Then, processing apparatus <NUM> has the average value of the square values of the amplitudes stored in association with the selected time and the selected frequency band (step S1026).

Processing apparatus <NUM> determines whether or not selection of all frequency bands has been completed (step S1027). When selection of all frequency bands has not been completed (NO in step S1027), processing in step S1024 or later is repeated.

When selection of all frequency bands has been completed (YES in step S1027), processing apparatus <NUM> determines whether or not selection of all times has been completed (step S1028). When selection of all times has not been completed (NO in step S1028), processing in step S1022 or later is repeated.

When selection of all times has been completed (YES in step S1028), processing apparatus <NUM> determines whether or not selection of all channels has been completed (step S1029). When selection of all channels has not been completed (NO in step S1029), processing in step S1021 or later is repeated.

When selection of all channels has been completed (YES in step S1029), at this stage, processing for calculating time waveform <NUM> of power for each frequency band is completed. Then, processing for calculating time waveform <NUM> (FC) of EEG time correlation follows.

Processing apparatus <NUM> selects window setting (the window size and the step size) of interest of calculation of EEG time correlation (step S1041) and selects a frequency band of interest of calculation of EEG time correlation (step S1042).

For window setting (the window size and the step size), a plurality of combinations may be prepared in advance or only one type of window setting may be prepared.

Processing apparatus <NUM> selects a channel combination of interest of calculation of EEG time correlation (step S1043).

Then, processing apparatus <NUM> selects time of interest of calculation of EEG time correlation (step S1044), extracts time waveforms of power included in the window with the selected time being defined as the reference position for two channels corresponding to the selected channel combination (step S1045), and calculates a correlation value of the extracted time waveforms of power (step S1046). Then, processing apparatus <NUM> has the calculated correlation value stored in association with the selected time, channel combination, frequency band, and window setting (step S1047).

Processing apparatus <NUM> determines whether or not selection of all times has been completed (step S1048). When selection of all times has not been completed (NO in step S1048), processing in step S1044 or later is repeated.

When selection of all times has been completed (YES in step S1048), processing apparatus <NUM> determines whether or not selection of all channel combinations has been completed (step S1049). When selection of all channel combinations has not been completed (NO in step S1049), processing in step S1043 or later is repeated.

When selection of all channel combinations has been completed (YES in step S1049), processing apparatus <NUM> determines whether or not selection of all frequency bands has been completed (step S1050). When selection of all frequency bands has not been completed (NO in step S1050), processing in step S1042 or later is repeated.

When selection of all frequency bands has been completed (YES in step S1050), processing apparatus <NUM> determines whether or not selection of all window settings has been completed (step S1051). When selection of all window settings has not been completed (NO in step S1051), processing in step S1041 or later is repeated.

When selection of all window settings has been completed (YES in step S1051), at this stage, processing for calculating time waveform <NUM> (FC) of EEG time correlation is completed.

"(<NUM>) Estimate disorder-likelihood based on a plurality of brain networks" shown in <FIG> and steps S112 to S118 shown in <FIG> will now be described in detail.

Initially, in preprocessing (step S112) on fMRI measurement data <NUM> (brain activity pattern image), BOLD signal <NUM> for each ROI is calculated from the brain activity pattern image. In extraction of this BOLD signal <NUM>, processing for compensating for delay in time caused in fMRI is performed.

More specifically, transform y(t) into a BOLD signal representing an amount of activity for each ROI corresponds to addition of an error e(t) to convolution of s(t) and h(t) as shown in an expression (<NUM>) below, where s(t) represents BOLD signal <NUM> representing a neural state of the ROI to which attention is paid and h(t) represents a hemodynamic response function (HRF).

HRF(t) is dependent on emission cycle TR of RF pulses in fMRI.

An estimated value ŝ(t) of the neural state can be expressed as in an expression (<NUM>) below, with the use of a Wiener filter d(t).

With H(x), Y(x), E(x), and D(x) being defined as results of Fourier transform of h(t), y(t), e(t), and d(t), estimated value ŝ(t) of the neural state can be expressed as in an expression (<NUM>) below.

Estimated value ŝ(t) of the neural state shown in the expression (<NUM>) above corresponds to the BOLD signal. In other words, estimated value s(t) of the neural state is estimated by deconvolution of observed y(t) with HRF. By deconvolution with HRF, delay in time (displacement between measurement points) between EEG measurement data <NUM> and fMRI measurement data <NUM> is compensated for.

<FIG> is a diagram for illustrating overview of preprocessing on EEG measurement data <NUM> and fMRI measurement data <NUM>.

Referring to <FIG>, window <NUM> is set for EEG measurement data <NUM> by being sequentially shifted by each step size, and time waveform <NUM> of EEG time correlation can be calculated by calculating EEG time correlation for each window <NUM>.

For fMRI measurement data <NUM>, deconvolution with HRF compensates for delay in time involved with emission of RF pulses and then BOLD signal <NUM> is calculated. In other words, by deconvolution with HRF, the time axis of EEG measurement data <NUM> and the time axis of BOLD signal <NUM> can substantially match with each other. Then, disorder-likelihood label <NUM> is calculated based on BOLD signal <NUM>.

In step S114 in <FIG>, for each combination of two ROIs, the window is sequentially shifted along the time axis and a correlation value between time waveforms of the BOLD signals within the window is sequentially calculated. The combination of two ROIs may be a combination of identical ROIs.

In steps S116 and S118 in <FIG>, time waveforms of a plurality of BOLD time correlations in accordance with disorder-likelihood to be estimated are multiplied with respective corresponding weight parameters, and results of multiplication are added to calculate WLS. Furthermore, by normalizing and binarizing the calculated WLS, the disorder-likelihood label representing disorder-likelihood is calculated. More specifically, WLS <NUM> can be calculated as in an expression (<NUM>) shown below, based on time waveform <NUM> (FC'(k)) of kth BOLD time correlation and a corresponding weight parameter WFC(k).

WLS is a score which represents a larger numeric value as a degree of disorder-likelihood is higher, with <NUM> being defined as a boundary. WLS can be normalized to a probability p in accordance with an expression (<NUM>) shown below.

Probability p (<NUM> ≤ p ≤ <NUM>) is closer to <NUM> as the degree of disorder-likelihood is higher, with <NUM> being defined as a boundary.

In accordance with the disorder-likelihood to be estimated, functional connectivity (FC') of interest is selected. For example, NPL <NUM> discloses a disorder discriminator for schizophrenia (SCZ) with the use of sixteen functional connectivities (FC'). NPL <NUM> discloses a disorder discriminator for melancholic major depressive disorder (MDD) with the use of ten functional connectivities (FC').

By referring to such prior art, in accordance with disorder-likelihood to be estimated, a plurality of functional connectivities (FC') are selected, and WLS can be determined by calculating the sum of values obtained by multiplication of the plurality of functional connectivities by respective weight parameters WFC brought in correspondence with selected functional connectivities (FC').

By finally binarizing probability p, the disorder-likelihood label can be calculated.

<FIG> is a flowchart showing a more detailed processing procedure in steps S112 to S118 shown in <FIG>. Referring to <FIG>, processing apparatus <NUM> selects an ROI of interest of calculation of a BOLD signal (step S1121) and extracts each amount of activity from an image feature value in a region corresponding to the ROI selected from fMRI measurement data <NUM> (step S1122). By deconvolution of change over time in extracted amount of activity with HRF, a time waveform of the BOLD signal is calculated (step S1123) and the time waveform is stored in association with the selected ROI (step S1124).

Processing apparatus <NUM> determines whether or not selection of all ROIs has been completed (step S1125). When selection of all ROIs has not been completed (NO in step S1125), processing in step S1121 or later is repeated.

When selection of all ROIs has been completed (YES in step S1125), at this stage, processing for calculating a BOLD signal for each ROI is completed. Then, processing for calculating time waveform <NUM> of BOLD time correlation follows.

Processing apparatus <NUM> selects an ROI combination of interest of calculation of BOLD time correlation (step S1141).

Then, processing apparatus <NUM> selects time of interest of calculation of BOLD time correlation (step S1142), extracts time waveforms of BOLD signals <NUM> included in a window with the selected time being defined as the reference position for two ROIs corresponding to the selected ROI combination (step S1143), and calculates a correlation value of the extracted time waveforms of the BOLD signals (step S1144). Then, processing apparatus <NUM> has the calculated correlation value stored in association with the selected time and ROI combination (step S1145).

Processing apparatus <NUM> determines whether or not selection of all times has been completed (step S1146). When selection of all times has not been completed (NO in step S1146), processing in step S1142 or later is repeated.

When selection of all times has been completed (YES in step S1146), processing apparatus <NUM> determines whether or not selection of all ROI combinations has been completed (step S1147). When selection of all ROI combinations has not been completed (NO in step S1147), processing in step S1141 or later is repeated.

When selection of all ROI combinations has been completed (YES in step S1147), at this stage, processing for calculating time waveform <NUM> of BOLD time correlation is completed. Then, processing for calculating WLS follows.

Processing apparatus <NUM> selects disorder-likelihood to be estimated (step S1161) and determines a plurality of brain networks (ROI combination) associated with selected disorder-likelihood (step S1162). Processing apparatus <NUM> determines weight parameters corresponding to respective ones of the plurality of determined brain networks (step S1163). Then, processing apparatus <NUM> multiplies time waveforms <NUM> of BOLD time correlations of the plurality of determined brain networks by respective corresponding weight parameters and calculates the sum of results of multiplication (step S1164). The calculated sum is adopted as WLS corresponding to the disorder-likelihood to be estimated.

Processing apparatus <NUM> determines whether or not selection of all disorder-likelihoods has been completed (step S1165). When selection of all disorder-likelihoods has not been completed (NO in step S1165), processing in step S1161 or later is repeated.

When selection of all disorder-likelihoods has been completed (YES in step S1165), at this stage, processing for calculating WLS for each disorder-likelihood is completed. Then, processing for calculating the disorder-likelihood label follows.

The processing apparatus calculates probability p by normalizing calculated WLS (step S1181) and outputs a string of a value <NUM> or <NUM> by subjecting calculated probability p to threshold processing (step S1182). The outputted string of the value <NUM> or <NUM> serves as the disorder-likelihood label representing disorder-likelihood.

"(<NUM>) Determine estimation model" shown in <FIG> and step S120 shown in <FIG> will now be described in detail.

In processing for determining an estimation model, machine learning of relation between time waveform <NUM> (FC) of EEG time correlation which is an explanatory variable and disorder-likelihood label <NUM> which is an explained variable is carried out to determine a prescribed number of (for example, thirty) feature values suitable for estimation of disorder-likelihood label <NUM> among a large number of feature values that compose a multi-dimensional vector included in time waveform <NUM> of EEG time correlation and corresponding weight parameters.

Though any machine learning algorithm can be employed as a technique for such machine learning, an example in which SLR is adopted will be described by way of example. A specific processing procedure in SLR will be described below.

An expression (<NUM>) shown below is assumed as a linear discriminant function for discrimination of two classes S<NUM> and S<NUM> based on a weighted sum of feature values.

In the expression, x represents a feature value (x = (x<NUM>, x<NUM>,. , xD)t ∈ RD) within a D-dimensional space and θ represents a weight vector (θ = (θ<NUM>, θ<NUM>,. , θD)t) including a bias term. A hyperplane corresponding to f(x; θ) = <NUM> defines a boundary between class S<NUM> and class S<NUM>.

In SLR, possibility that each feature value belongs to class S<NUM> on the hyperplane that defines the boundary between class S<NUM> and class S<NUM> is computed with the use of a logistic function as shown in an expression (<NUM>).

In the expression, probability p has a value within a range from <NUM> to <NUM>, and the probability attains to <NUM> when a condition of f(x; θ) = <NUM> is satisfied (being on the hyperplane) and exhibits <NUM> when f(x; θ) = <NUM> is located at a positive or negative infinite point (a position distant from the hyperplane). In other words, probability p means possibility that any feature value x belongs to class S<NUM>.

By introduction of any binary output variable y (y = <NUM> corresponds to class S<NUM> and y = <NUM> corresponds to class S<NUM>), a probability function as shown in an expression (<NUM>) below can be defined for a data string {(x<NUM>, y<NUM>), (x<NUM>, y<NUM>),. , (xN, yN)} including N input-output elements. <MAT> <MAT>.

Since each term in the expression (<NUM>) expresses a probability pn of an nth sample (pn when yn = <NUM> and <NUM>-pn when yn = <NUM>) (see an expression (<NUM>)), a product of the terms shown in the expression (<NUM>) means the probability of all samples included in the data string.

Machine learning aims at introduction of a probability function l(θ) as shown in an expression (<NUM>) and search for a weight vector θ that maximizes a value of probability function l(θ) defined in the expression (<NUM>).

Probability function l(θ) includes probability pn of a non-linear element dependent on weight vector θ. Therefore, for solving probability function l(θ), a gradient and a Hessian matrix can be used. When weight vector θ (=(θ<NUM>, θ<NUM>,. , θD)t) that maximizes probability function l(θ) can be determined, at least one of feature values can be selected as the feature value suitable for estimation based on a value of an element (weight parameter) included in weight vector θ.

For example, a prescribed number of (for example, thirty) weight parameters are selected in a descending order of magnitude, and feature values corresponding to the selected weight parameters are selected.

The feature value (designation of a channel pair, a frequency band, and a window size to be used in EEG time correlation) and the corresponding weight parameter to be used for estimation of disorder-likelihood label <NUM> can thus be determined.

<FIG> is a diagram for illustrating overview of the determined estimation model. Referring to <FIG>, in the estimation phase, time waveform <NUM> of EEG time correlation is inputted to estimation model <NUM>. More specifically, an amount of information on a prescribed window size (for example, thirty seconds) is inputted for each step size (for example, thirty seconds).

Estimation model <NUM> includes a plurality of combinations of feature value information <NUM> and a weight parameter <NUM>. Only information corresponding to feature value information <NUM> (EEG time correlation selected as the feature value) included in estimation model <NUM> in inputted time waveform <NUM> of EEG time correlation is used. Then, the used EEG time correlation is multiplied by corresponding weight parameter <NUM>, a sum of results thereof is calculated by an adder <NUM>, and the sum is binarized to <NUM> or <NUM> by a binarizer <NUM>. A result of binarization is outputted as disorder-likelihood.

Though the channel pair, the frequency band, and the window size are each defined as a variable factor in determination of the estimation model, the frequency band and the window size may be determined in advance as a feature value condition.

More specifically, in determining a feature value condition (the frequency band and the window size), EEG/fMRI simultaneous measurement data is obtained in a plurality of sessions and a frequency band and a window size highest in discrimination performance (for example, an indicator shown with area under the curve (AUC)) may be determined by such a technique as cross validation. By thus determining the feature value condition in advance, an amount of computation necessary for processing for determining the estimation model can be reduced.

The frequency band and/or the window size included in EEG measurement data <NUM> to be inputted to the estimation model may thus be determined in advance depending on a subject.

Exemplary processing in the estimation phase using the estimation model determined in the processing in the learning phase as described above will now be described.

In the estimation phase, EEG measurement data measured from the subject is inputted to the estimation model to estimate disorder-likelihood of the subject. Neurofeedback training represents a typical application of such an estimation phase.

<FIG> is a diagram for illustrating overview of neurofeedback training using the estimation method according to the present embodiment. Referring to <FIG>, a brain activity training apparatus <NUM> for conducting neurofeedback training includes an EEG apparatus <NUM>, a storage device <NUM>, a display device <NUM>, and a processing apparatus <NUM>.

An estimation model is stored in storage device <NUM>. The estimation model stored in storage device <NUM> is generated before neurofeedback training is conducted. Storage device <NUM> may be implemented by a storage included in processing apparatus <NUM> or a server apparatus <NUM> shown in <FIG>.

Display device <NUM> represents an exemplary presentation apparatus and provides visual and/or aural information to a user.

EEG apparatus <NUM> corresponds to an electroencephalograph and measures measurement data of brain waves of subject S in neurofeedback training. Measurement data of brain waves measured by EEG apparatus <NUM> includes a time waveform for a plurality of channels corresponding to respective ones of a plurality of sensors arranged in a head of subject S, as in EEG apparatus <NUM> shown in <FIG>. In other words, since substantially the same EEG apparatus <NUM> is used in generation of the estimation model and in neurofeedback training, EEG measurement data included in EEG/fMRI simultaneous measurement data used in generation of the estimation model includes a time waveform for each channel corresponding to each channel of EEG measurement data measured in neurofeedback training.

Processing apparatus <NUM> obtains EEG measurement data by EEG from subject S and estimates disorder-likelihood with the estimation model determined in advance. Disorder-likelihood is estimated every cycle (typically, every step size). Processing apparatus <NUM> calculates a score in accordance with the estimated disorder-likelihood and provides a score representation <NUM> in accordance with the calculated score on display device <NUM>. Processing apparatus <NUM> thus calculates the score in accordance with disorder-likelihood of subject S with the estimation model based on measurement data from EEG apparatus <NUM> and presents information in accordance with the calculated score to the subject. In other words, processing apparatus <NUM> outputs a signal for representation corresponding to disorder-likelihood to display device <NUM>.

Processing apparatus <NUM> may be implemented by execution of a brain activity training program by a general-purpose computer.

For example, score representation <NUM> includes a reference circle <NUM> and a score circle <NUM> varied in size in accordance with the score. In accordance with disorder-likelihood estimated based on EEG measurement data measured from subject S, the size of score circle <NUM> is sequentially updated.

Subject S is informed in advance of the fact that the subject is rewarded as score circle <NUM> is close to reference circle <NUM> or score circle <NUM> deviates from reference circle <NUM>. Subject S is more conscious of use of the brain for calculation, association, meditation, or the like such that the size of score circle <NUM> moves in a designated direction on the user's own will or in response to an external instruction. As subject S is more conscious of use of the brain, aimed alleviation or treatment of a disorder can be achieved.

In neurofeedback training where the estimation method according to the present embodiment is made use of, disorder-likelihood can be estimated at any location so long as estimation model <NUM> and EEG measurement data <NUM> are available. With the use of such an advantage, for example, EEG and fMRI are simultaneously conducted once with the use of a dedicated facility and thereafter neurofeedback training can be performed at any location.

<FIG> is a schematic diagram showing an implementation of the estimation method according to the present embodiment. Referring to <FIG>, for example, at a dedicated measurement station, EEG and fMRI of each subject are simultaneously measured, and processing apparatus <NUM> determines estimation model <NUM> for each subject. Determined estimation model <NUM> is transmitted from the measurement station to server apparatus <NUM>.

Subject data <NUM> including the estimation model for each subject is held in server apparatus <NUM>.

Not only the measurement station but also a clinic desired by each subject of one or more clinics accesses server apparatus <NUM> to obtain the estimation model corresponding to each subject. At each clinic, processing apparatus <NUM> as will be described later is arranged and neurofeedback training as shown in <FIG> is conducted based on the obtained estimation model.

Cost for conducting neurofeedback training can be reduced with the use of a system as shown in <FIG>.

An exemplary functional configuration of an apparatus included in estimation system <NUM> that realizes the estimation method according to the present embodiment will now be described.

<FIG> is a schematic diagram showing an exemplary functional configuration of processing apparatus <NUM> in estimation system <NUM> according to the present embodiment. Each function shown in <FIG> is typically performed by execution of an estimation model determination program by processor <NUM> of processing apparatus <NUM>.

Estimation model determination program <NUM> may be executed by one processor or a plurality of processors included in processing apparatus <NUM> or by a plurality of processing apparatuses in coordination with one another. In the latter example, a plurality of computers arranged on a network, or what is called a cloud system, may be used. Furthermore, instead of a configuration implemented by execution of a program by the processor (software implementation), the entirety or a part thereof may be implemented by a hard-wired configuration such as a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

Each program according to the present embodiment may be mounted in such a form as utilizing a function provided by an operating system (OS), and such an example may also be encompassed in the technical scope of the invention of the present application.

Referring to <FIG>, processing apparatus <NUM> includes preprocessing modules <NUM> and <NUM>, time correlation calculation modules <NUM> and <NUM>, a WLS calculation module <NUM>, a binarization module <NUM>, and a model estimation module <NUM>.

Preprocessing module <NUM> converts EEG measurement data <NUM> into time waveform <NUM> of power. Time waveform <NUM> of power may be calculated for each frequency band and/or window size.

Time correlation calculation module <NUM> calculates time waveform <NUM> of EEG time correlation from time waveform <NUM> of power for each of channel combinations (channel pairs).

Preprocessing module <NUM> calculates BOLD signal <NUM> for each ROI from fMRI measurement data <NUM>.

Time correlation calculation module <NUM> calculates time waveform <NUM> (FC') of BOLD time correlation from BOLD signal <NUM> for each ROI.

WLS calculation module <NUM> calculates WLS <NUM> which is a score representing disorder-likelihood to be estimated, based on time waveforms <NUM> of BOLD time correlations corresponding to a plurality of brain networks associated with disorder-likelihood to be estimated.

Binarization module <NUM> calculates disorder-likelihood label <NUM> (label) which represents a result of normalization of WLS <NUM> and binarization of disorder-likelihood.

Model estimation module <NUM> determines a feature value and a weight parameter for estimating disorder-likelihood label <NUM> based on time waveform <NUM> of EEG time correlation and disorder-likelihood label <NUM>. A set of determined feature value and weight parameter is outputted as estimation model <NUM>.

An exemplary functional configuration implemented in processing apparatus <NUM> shown in <FIG> and <FIG> will now be described. Since processing apparatus <NUM> is similar in hardware configuration to processing apparatus <NUM> shown in <FIG> described above, detailed description will not be repeated.

<FIG> is a schematic diagram showing an exemplary functional configuration of processing apparatus <NUM> in estimation system <NUM> according to the present embodiment. Each function shown in <FIG> is performed by execution of an estimation program (similar to estimation program <NUM> shown in <FIG>) by the processor of processing apparatus <NUM>.

The estimation program may be executed by one or more processors in processing apparatus <NUM> or by a plurality of processing apparatuses in coordination with one another.

In the latter example, a plurality of computers arranged on a network, or what is called a cloud system, may be used. Furthermore, instead of a configuration implemented by execution of a program by the processor (software implementation), the entirety or a part thereof may be implemented by a hard-wired configuration such as an FPGA or an ASIC.

Each program according to the present embodiment may be mounted in such a form as utilizing a function provided by an OS, and such an example may also be encompassed in the technical scope of the invention of the present application.

Referring to <FIG>, processing apparatus <NUM> includes a preprocessing module <NUM>, a time correlation calculation module <NUM>, a weighted sum calculation module <NUM>, a binarization module <NUM>, an estimation model obtaining module <NUM>, and a representation control module <NUM>.

Estimation model obtaining module <NUM> obtains estimation model <NUM> corresponding to a subject from server apparatus <NUM> or the like. Estimation model <NUM> includes a set of a feature value and a weight parameter for estimating disorder-likelihood label <NUM>.

Weighted sum calculation module <NUM> selects one feature value or a plurality of feature values (EEG time correlation(s)) of interest in time waveforms <NUM> of EEG time correlations in accordance with estimation model <NUM> obtained by estimation model obtaining module <NUM> and calculates as WLS <NUM>, the sum of values obtained by multiplication of feature value(s) by respective corresponding weight parameter(s).

Binarization module <NUM> calculates disorder-likelihood (<NUM> or <NUM>) which represents a result of normalization of WLS <NUM> and binarization of disorder-likelihood.

Representation control module <NUM> calculates a score based on a value of disorder-likelihood sequentially outputted from binarization module <NUM> and calculates score representation <NUM> for representation on display device <NUM>. Change in symptom of the subject is thus assessed based on the score in accordance with the estimated disorder-likelihood of the subject.

Some of results obtained by application of the estimation method according to the present embodiment to actual subjects will now be described.

In examples which will be described below, a healthy person or a subject determined as being subclinical was defined as a target. Being subclinical means a state determined to highly likely to exhibit at least one symptom of a disorder of interest based on contents of answers to questions for assessing a degree of the symptom.

An exemplary result of assessment of accuracy in estimation of a feature value condition for determining an estimation model will initially be described.

Each subject was simultaneously subjected to EEG and fMRI in a resting state to obtain EEG/fMRI simultaneous measurement data. EEG/fMRI simultaneous measurement data in at least eight sessions (equal to or shorter than five minutes per session) was obtained for each subject. Two disorders of interest, that is, schizophrenia (SCZ) (see NPL <NUM>) and depression (MDD) (see NPL <NUM>), were assumed.

Of obtained EEG/fMRI simultaneous measurement data in eight sessions, EEG/fMRI simultaneous measurement data in seven sessions was used to determine the estimation model and EEG/fMRI simultaneous measurement data in one remaining session was used as validation data, to thereby assess estimation performance by leave one out cross validation (LOOCV). Mean AUC was employed as an indicator for assessment of estimation performance.

<FIG> is a diagram showing an exemplary result of assessment of a feature value condition in the estimation method according to the present embodiment. <FIG> shows variation in estimation performance with variation in window size in calculation of time correlation (<NUM> TR, <NUM> TR, <NUM> TR, <NUM> TR, and <NUM> TR). TR represents an emission cycle of RF pulses.

<FIG> shows an exemplary result of assessment when schizophrenia (SCZ) was defined as the disorder of interest and <FIG> shows an exemplary result of assessment when depression (MDD) was defined as the disorder of interest.

As shown in <FIG>, with variation in window size, an average value of the mean AUC and a degree of variation thereof were also varied.

As shown in <FIG>, regarding schizophrenia (SCZ), it can be seen that the overall average of the mean AUC was good when the window size as the feature value condition was set to <NUM> TR. When the window size was set to <NUM> TR, however, some of subjects exhibited the highest mean AUC.

As shown in <FIG>, regarding depression (MDD), variation was less than variation in the case of schizophrenia (SCZ). Regarding depression (MDD), it can be seen that the overall average of the mean AUC was good when the window size as the feature value condition was set to <NUM> TR or <NUM> TR.

As shown in <FIG>, it can be seen that selection of an optimal feature value condition for each subject is preferred.

Specificity depending on target of the estimation model will now be described.

<FIG> described above shows the result of assessment of performance in estimation of the score representing disorder-likelihood of schizophrenia (SCZ) for the estimation model determined from EEG measurement data in connection with schizophrenia (SCZ) (which will also be referred to as a "schizophrenia estimation model" below) and the result of assessment of performance in estimation of the score representing disorder-likelihood of depression (MDD) for the estimation model determined from EEG measurement data in connection with depression (MDD) (which will also be referred to as a "depression estimation model" below). An exemplary result of cross assessment of these models is shown below.

<FIG> is a diagram showing an exemplary result of assessment of specificity depending on target of the estimation model determined by the estimation method according to the present embodiment.

<FIG> shows estimation performance (mean AUC) in estimation of disorder-likelihood of schizophrenia (SCZ) and estimation performance in estimation of disorder-likelihood of depression (MDD) with the use of the schizophrenia estimation model. <FIG> shows estimation performance in estimation of disorder-likelihood of depression (MDD) and estimation performance in estimation of disorder-likelihood of schizophrenia (SCZ) with the use of the depression estimation model.

As shown in <FIG>, the schizophrenia estimation model exhibits estimation performance specific for estimation of disorder-likelihood of schizophrenia (SCZ). As shown in <FIG>, on the other hand, the depression estimation model exhibits estimation performance specific for estimation of disorder-likelihood of depression (MDD).

According to the result of cross validation of accuracy in estimation of disorder-likelihood shown in <FIG>, it can be seen that the estimation model determined by the estimation method according to the present embodiment is target specific.

Exemplary neurofeedback training with the estimation model determined by the estimation method according to the present embodiment will now be described.

<FIG> is a diagram for illustrating a technique for neurofeedback training with the estimation model determined by the estimation method according to the present embodiment. Referring to <FIG>, according to scheduling of training (for one day), a set <NUM> composed of a plurality of blocks <NUM> is carried out over a plurality of days. Each of blocks <NUM> includes a plurality of cycles <NUM>. Each of cycles <NUM> includes a series of processes composed of an interval <NUM> (a duration T1), an induction period <NUM> (a duration T2), and a representation period <NUM> (a duration T3).

Interval <NUM> corresponds to an intermission following a previous cycle <NUM>. Induction period <NUM> corresponds to a period for which the subject is more conscious of use of the brain for calculation, association, meditation, or the like for achieving assessment as a higher score, on the subject's own will or in response to an external instruction. Representation period <NUM> corresponds to a period for which a score calculated from the subject during induction period <NUM> is shown.

During induction period <NUM>, disorder-likelihood of the subject is estimated based on EEG measurement data measured by EEG from the subject. During induction period <NUM>, estimation of disorder-likelihood of the subject may be repeated a plurality of times. Since the result of estimation (<NUM> or <NUM>) of disorder-likelihood is calculated a plurality of times, the score representing the degree of disorder-likelihood of the subject during induction period <NUM> can be calculated by averaging the results.

For example, when an estimation model in which "<NUM>" means being healthy is adopted, the score representing the degree of disorder-likelihood of the subject is preferably smaller. Score representation <NUM> in accordance with the calculated score is provided to the subject. In score representation <NUM>, as the score is smaller, score circle <NUM> is closer to reference circle <NUM>.

The subject is rewarded with money or the like in accordance with the score. By being motivated by such a reward, the subject tries to make a higher score.

For example, approximately five seconds is set as duration T1 of interval <NUM>. For example, approximately fifty to seventy seconds is set as duration T2 of induction period <NUM>. For example, approximately five seconds is set as duration T3 of representation period <NUM>.

In an example below, two disorders of interest, that is, schizophrenia (SCZ) (see NPL <NUM>) and depression (MDD) (see NPL <NUM>), were assumed.

A sampling frequency in EEG was set to <NUM>, and EEG measurement data was processed to remove an artifact (a specific independent component of the subject extracted in advance).

A length (window size) of EEG measurement data for estimation of disorder-likelihood was set to an integral multiple of emission period TR of RF pulses in fMRI. More specifically, for schizophrenia (SCZ), the length was set to <NUM> TR (<NUM> seconds × <NUM> = <NUM> seconds), and for depression (MDD), the length was set to <NUM> TR (<NUM> seconds × <NUM> = <NUM> seconds).

Accordingly, duration T2 of induction period <NUM> for schizophrenia (SCZ) was set to seventy seconds, and duration T2 of induction period <NUM> for depression (MDD) was set to eighty-five seconds.

<FIG> is a diagram showing an exemplary result of neurofeedback training in connection with schizophrenia (SCZ). <FIG> shows an experimental example of WLS which is the score representing disorder-likelihood to be estimated before and after training. <FIG> shows an experimental example of a schizotypal personality questionnaire (SPQ) before and after training. SPQ represents an exemplary schizophrenia-like score. <FIG> shows an experimental example of an n-back task before and after training.

"A" to "I" in <FIG> represent subjects. A smaller value of WLS shown in <FIG> and a smaller value of SPQ shown in <FIG> mean amelioration of a symptom. Though a significant result is not exhibited in WLS shown in <FIG>, a tendency of improvement owing to training is observed in SPQ shown in <FIG>.

The n-back task shown in <FIG> is a test for assessing capability (a cognition function) to remember information presented N times earlier. A result in the n-back task is shown with a score "d prime. " A larger value of d prime means improvement in cognition function. <FIG> shows a result in an example where N was set to <NUM>, <NUM>, and <NUM> (N = <NUM>, <NUM>, <NUM>). A tendency of improvement owing to training is observed in the n-back task shown in <FIG>. In particular, in a <NUM>-back test, significant change in a paired t-test is observed.

<FIG> is a diagram showing an exemplary result of neurofeedback training in connection with depression (MDD). <FIG> shows an experimental example of WLS which is the score representing disorder-likelihood to be estimated before and after training. <FIG> shows an experimental example of the Beck depression inventory (BDI) and the self-rating depression scale (SDS) before and after training. BDI and SDS are exemplary scores of a depression-like symptom. <FIG> shows an experimental example of achievement in an n-back task before and after training.

"A" to "G" in <FIG> represent subjects. A smaller value of WLS shown in <FIG> and smaller values of BDI and SDS shown in <FIG> mean amelioration of a symptom. According to the exemplary results shown in <FIG>, a tendency of improvement owing to training is observed. According to the exemplary result shown in <FIG>, a tendency of improvement in the n-back task owing to training is also observed.

Exemplary assessment of a long-term effect including a result in follow-up (FU) one to two months after the end of neurofeedback training will now be described.

<FIG> is a diagram showing an exemplary procedure for assessing a long-term effect of neurofeedback training with the estimation model determined by the estimation method according to the present embodiment.

Referring to <FIG>, training was conducted for three days, and measurement (calculation of the score) was conducted on a day preceding a training period (Pretraining), on a day following the training period (Posttraining), and on a follow-up (FU) day one to two months after the training period.

<FIG> is a diagram showing an exemplary long-term effect of neurofeedback training in connection with depression (MDD). <FIG> shows an experimental example of WLS. <FIG> shows an experimental example of BDI. <FIG> shows an experimental example of RRS which is a score representing a frequency of rumination. A smaller value of RRS can be determined as indicating a preferred state.

Each of <FIG> shows variation in score of each subject with a line graph and shows variation in average score of all subjects with a bar graph.

The WLS shown in <FIG> can generally be concluded as being significant as the score representing disorder-likelihood, although there is variation among individual subjects.

For BDI shown in <FIG>, a low state is maintained at both of timing immediately after training (Post) and timing one to two months later (FU), which suggests that the effect of training lasts for a long time. <FIG> shows also a sub score used for calculation of BDI. The sub score also exhibits the tendency similar to the tendency of BDI.

For RRS shown in <FIG>, a low state is maintained at both of timing immediately after training (Post) and timing one to two months later (FU), which suggests that the effect of training lasts for a long time. <FIG> shows also a sub score used for calculation of RRS. The sub score also exhibits the tendency similar to the tendency of RRS.

<FIG> is a diagram showing an exemplary long-term effect of neurofeedback training in connection with schizophrenia (SCZ). <FIG> shows variation in WLS of each subject with a line graph and shows variation in averaged score of WLS of all subjects with a bar graph.

In <FIG>, "CTRL" represents a result of a control group. The control group represents a set of subjects who conducted training with the use, as feedback information, of information on others prepared in advance rather than information from target persons. In other words, the experimental example of the control group shows a result of training in which the subject conducted training presuming that the training was based on the brain activity of the subject himself/herself in spite of the fact that the brain activity of the subject was not referred to. This is also applicable to experimental examples below.

The WLS shown in <FIG> is significantly different from that of the control group, although there is variation among individual subjects, and the WLS exhibits a tendency of improvement owing to training.

An exemplary effect of neurofeedback training with a control group being defined as a benchmark will now be described.

<FIG> is a diagram showing an effect of neurofeedback training in connection with schizophrenia (SCZ) as compared with the control group. The ordinate of the graph shown in <FIG> represents change (Post-Pre) in value before and after neurofeedback.

It can be seen that the control group (CTRL) is distributed around a point where values before and after training are not varied (a value on the ordinate is zero), whereas an appropriately trained group is distributed around a point on a negative side (that is, the value of SPQ became smaller after training). <FIG> also shows a sub score used for calculation of SPQ. The sub score also exhibits the tendency similar to the tendency of SPQ.

The SPQ shown in <FIG> also exhibits a significant difference from that of the control group and exhibits the tendency of improvement owing to training.

<FIG> is another diagram showing an effect of neurofeedback training in connection with schizophrenia (SCZ) as compared with the control group. The ordinate of the graph shown in each of <FIG> represents change (Post-Pre) in value before and after neurofeedback. Each of <FIG> shows an experimental example of the score of the cognition function.

More specifically, <FIG> shows an experimental example in an n-back task (N = <NUM>) and <FIG> shows an experimental example in an n-back task (N = <NUM>). In each experimental example, a control group (CTRL) is distributed around a point where values before and after training are not varied (a value on the ordinate is zero), whereas an appropriately trained group is distributed around a point on a positive side (that is, the value of d prime became larger after training).

<FIG> shows exemplary assessment of the cognition function with the use of Cambridge neuropsychological test automated battery (CANTAB) (see NPL <NUM> or the like). More specifically, rapid visual information processing (RVP) is assessed. A schizophrenic has been reported to be lower in sustained attention function.

A' and p(Hit) are outputted as the scores. Larger values of A' and p(Hit) are preferred. For calculation of these scores, software called "CANTAB(R) [Cognitive assessment software]. Cambridge Cognition (<NUM>). All rights reserved. com" was used.

It can be seen in each experimental example that the control group (CTRL) is distributed around a point where values before and after training are not varied (a value on the ordinate is zero), whereas an appropriately trained group is distributed around a point on a positive side (that is, the values of A' and p(Hit) became larger after training).

As shown in <FIG> and <FIG>, possibility of amelioration of a symptom owing to training tends to strongly be suggested.

Though neurofeedback training itself achieves a non-specific effect such as a learning effect, achievement of a specific effect exceeding such a non-specific effect by neurofeedback training with the estimation model determined by the estimation method according to the present embodiment will be described with reference to an experimental example.

<FIG> is a diagram showing an experimental example for assessing specificity of the effect of neurofeedback training. <FIG> shows exemplary change in RRS and sub score as a psychological indicator in connection with depression (MDD). <FIG> shows exemplary change in SPQ and sub score as a psychological indicator in connection with schizophrenia (SCZ).

In <FIG>, "MDD" represents a group trained with the estimation model (depression estimation model) determined based on EEG measurement data in connection with depression (MDD) and "SCZ" represents a group trained with the estimation model (schizophrenia estimation model) determined based on EEG measurement data in connection with schizophrenia (SCZ). "CTRL" represents a control group.

It can be seen in connection with the psychological indicator of depression (MDD) shown in <FIG> that specific change in each of RRS (total score) and the sub score occurred in the group (MDD) trained with the depression estimation model.

It can be seen in connection with the psychological indicator of schizophrenia (SCZ) shown in <FIG> that specific change in each of SPQ (total score) and the sub score occurred in the group (SCZ) trained with the schizophrenia estimation model.

<FIG> is a diagram showing another experimental example for assessing specificity of the effect of neurofeedback training. <FIG> shows exemplary variation in cognition function. <FIG> shows an experimental example of an n-back task (N = <NUM>) and <FIG> shows an experimental example of an n-back task (N = <NUM>).

The experimental example shown in <FIG> exhibits a tendency of improvement in cognition function owing to training with any of the depression estimation model and the schizophrenia estimation model. The experimental example shown in <FIG> exhibits a tendency of significant improvement in cognition function owing to training with the schizophrenia estimation model.

These experimental examples exhibit the tendency of improvement in cognition function owing to neurofeedback training with the estimation model determined by the estimation method according to the present embodiment, and the higher tendency of improvement with the use of schizophrenia estimation model is observed.

With the estimation system according to the present embodiment, a brain function expressed in a plurality of brain networks and any disorder associated with the plurality of brain networks can be estimated in a more simplified manner with the use of EEG measurement data.

With the estimation system according to the present embodiment, since only a feature value effective for estimation of disorder-likelihood in EEG measurement data is used in the estimation model, dimensions of the estimation model can be compressed and reduced so that an amount of computation involved with estimation of disorder-likelihood can be reduced and estimation of disorder-likelihood can be accelerated.

With the estimation system according to the present embodiment, disorder-likelihood of any disorder associated with a plurality of brain networks can be estimated, so that neurofeedback training can be applied to various disorders.

With the estimation system according to the present embodiment, since the estimation model can be determined with the use of measurement data obtained by simultaneously conducting EEG and fMRI in a resting state, a task does not have to be provided to a subject in EEG and fMRI simultaneous measurement and hence burdens imposed on the subject in construction of the estimation model can be lessened.

Neurofeedback training provided by the estimation system according to the present embodiment provides a tendency of amelioration of some disorders and the tendency of amelioration is maintained for a long time.

The estimation model used in neurofeedback training provided by the estimation system according to the present embodiment exhibits specificity depending on target and is generated in accordance with a disorder.

It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims rather than the description of the embodiment above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claim 1:
An estimation system (<NUM>) comprising:
obtaining means (<NUM>; S100) configured to obtain brain wave measurement data (<NUM>) and functional magnetic resonance imaging measurement data (<NUM>) simultaneously measured from a subject (S), the brain wave measurement data including time waveforms for a plurality of channels corresponding to respective ones of a plurality of sensors (<NUM>) arranged in a head of the subject;
first calculation means (<NUM>, <NUM>; S102, S104) configured to calculate first functional connectivity (<NUM>) for each channel combination based on correlation between channels included in the brain wave measurement data;
second calculation means (<NUM>, <NUM>; S112, S114) configured to calculate second functional connectivity (<NUM>) for each brain network based on correlation between regions of interest included in the functional magnetic resonance imaging measurement data;
third calculation means (<NUM>, <NUM>; S116, S118) configured to calculate a disorder-likelihood label (<NUM>) by calculating a score (<NUM>) representing disorder-likelihood to be estimated based on a plurality of second functional connectivities; and
machine learning means (<NUM>; S120) configured to determine an estimation model (<NUM>) for estimating the disorder-likelihood based on prescribed first functional connectivity by machine learning using the first functional connectivity for each channel combination and the disorder-likelihood label.