Brain wave measuring device

Abstract

To enhance precision of ear periphery brain wave measurement as compared with a conventional technology.SOLUTION: A brain wave measuring device includes: an auricle periphery abutting member in which a plurality of electrodes for brain wave measurement are disposed along the outer periphery of the auricle separated by a predetermined distance each, the plurality of electrodes for brain wave measurement having a temporal bone abutting surface that abuts against the temporal bone upper outer crust in the periphery of the auricle; and a holding member for holding the auricle periphery abutting member at a position where the plurality of electrodes for brain wave measurement abut against the temporal bone outer crust in the periphery of the auricle.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to an apparatus for measuring electroencephalograms. [Background technology]

[0002] To realize a brain-computer interface (BCI), which is an interface connecting the human brain with a machine, a head-electroencephalogram (EEG) measuring device that places electrodes on the human head to measure brainwaves is already known. This head-electroencephalogram measuring device requires the user to wear a measuring cap that covers the entire head, or an assistant to place electrodes on the head one by one, making it difficult to wear the device on a human. To solve this problem and realize a wearable BCI, an ear-electroencephalogram measuring device that measures brainwaves obtained from the area around the ear has been developed in recent years.

[0003] Patent Document 1 (Japanese Patent No. 6963250) describes an ear electroencephalogram measuring device in which electrodes are provided on an ear attachment member that has a hook portion that can be hooked onto the auricle and an ear hole attachment portion that can be fitted into the ear hole.

[0004] Patent document 2 (Japanese Patent Publication No. 7211573) describes an ear electroencephalogram measuring device in which electrodes are provided on an ear attachment member that has a mounting part that is attached to a recess of the outer ear and an ear canal attachment part that is fitted into the ear canal.

[0005] Patent Document 3 (JP 2022-77070 A) describes an ear electroencephalogram measuring device in which electrodes are provided on the earpieces of glasses. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6963250 [Patent Document 2] Patent No. 7211573 [Patent Document 3] Patent Publication No. 2022-77070 Summary of the Invention [Problem to be solved by the invention]

[0007] Steady-state visual evoked potentials (SSVEPs) are responses observed when a subject gazes at a flashing stimulus, and are predominantly seen in the primary visual cortex at the back of the head.

[0008] However, the components of ear EEG are attenuated compared to head EEG, which reduces the accuracy of measuring minute reactions such as event-related potentials.

[0009] An object of the present invention is to improve the accuracy of ear electroencephalogram measurement compared to conventional techniques. [Means for solving the problem]

[0010] The first aspect is an electroencephalogram measuring device comprising: a plurality of electrodes for measuring electroencephalograms arranged at predetermined distances along the outer circumference of the auricle; an auricle peripheral abutment member having a temporal bone abutment surface where the plurality of electrodes for measuring electroencephalograms abut against the upper outer skin of the temporal bone around the auricle; and a holding member for holding the auricle peripheral abutment member at a position where the plurality of electrodes for measuring electroencephalograms abut against the outer skin of the temporal bone around the auricle.

[0011] The second aspect is an electroencephalogram measuring device of the first aspect, wherein the plurality of electrodes for electroencephalogram measuring are arranged at each position along the outer circumference of the auricle from at least the helical crus to the earlobe, and the auricle peripheral abutment member is formed into a curved shape.

[0012] The third aspect is the first aspect,

[0013] The electroencephalogram measuring device has an auricle peripheral contact member formed in a ring shape.

[0014] A fourth aspect is an electroencephalogram measuring device according to the first aspect, wherein the holding member is a conductive adhesive having electrical conductivity between the outer skin on the temporal bone and the electrode for electroencephalogram measuring and adhesiveness to the outer skin on the temporal bone, and the conductive adhesive is interposed between the electrode for electroencephalogram measuring and the outer skin on the temporal bone.

[0015] The fifth aspect is an electroencephalogram measuring device according to the first aspect, wherein the auricle peripheral abutment member has an engagement portion that engages with an inner portion of the auricle, and the engagement portion constitutes the retaining member.

[0016] A sixth aspect is an electroencephalogram (EEG) measuring device according to the first aspect, wherein the auricle peripheral abutment member is made of a flexible material that can be shaped to conform to the outer peripheral shape of the auricle, or is made to include a plurality of connecting members that are connected so as to be able to be flexibly shaped to conform to the outer peripheral shape of the auricle.

[0017] A seventh aspect is an electroencephalogram measuring device according to the sixth aspect, wherein the auricle peripheral abutment member is formed by connecting a plurality of connecting members together, and each of the connecting members is provided with the electroencephalogram measuring electrode and the holding member.

[0018] An eighth aspect is the electroencephalogram measuring device according to the fifth or sixth aspect, wherein the connecting member is formed with a recess for accommodating the electroencephalogram measuring electrode. Effect of the Invention

[0019] According to the first to eighth aspects, the accuracy of ear electroencephalogram measurement can be improved compared to the conventional techniques. [Brief description of the drawings]

[0020] [Figure 1A] FIG. 1A is a diagram showing an electroencephalogram measuring device according to an embodiment. [Figure 1B] FIG. 1B is a diagram showing an electroencephalogram measuring device according to an embodiment. [Figure 1C] FIG. 1C is a diagram showing a state in which an electroencephalogram measuring device is attached to a human left ear. [Figure 1D] FIG. 1D is a diagram showing a state in which an electroencephalogram measuring device is attached to a person's right ear. [Diagram 2] FIG. 2 is a diagram showing a configuration of the holding member. [Figure 3A] FIG. 3A is a diagram showing a configuration example in which the auricle-periphery contact member is formed into a ring shape. [Figure 3B] FIG. 3B is a diagram showing a configuration example in which the auricle-periphery contact member is formed into a ring shape. [Figure 4] FIG. 4 is a functional block diagram of the measurement unit. [Figure 5A] FIG. 5A is a diagram showing an example of the configuration of an electroencephalogram measuring device for performing wireless communication. [Figure 5B] FIG. 5B is a diagram showing an example of the configuration of an electroencephalogram measuring device for performing wireless communication. [Figure 6] FIG. 6 is a functional block diagram of the measurement unit. [Figure 7] FIG. 7 corresponds to FIG. 1A and shows another embodiment of an electroencephalogram measuring device worn on the left ear of a human. [Figure 8] 8(A) is an exploded view of the components shown in FIG. 7, and FIG. 8(B) is a partial cross-sectional view of FIG. [Figure 9] 9(A) and (B) are graphs showing a comparison of the alpha wave component of a subject's occipital electroencephalogram and the alpha wave component of the same subject's ear electroencephalogram. [Figure 10] 10(A) and 10(B) are graphs showing a comparison of the alpha wave power of the occipital EEG of each subject and the alpha wave power of the ear EEG of each subject. [Figure 11] 11(A) and (B) are diagrams showing a comparison between the SSVEP components of the occipital EEG of each subject and the SSVEP components of the ear EEG of each subject. [Figure 12] 12(A) and (B) are graphs showing the SSVEP increase rate of the occipital EEG of a subject in comparison with the SSVEP increase rate of the ear EEG of the same subject. [Figure 13] 13A and 13B are diagrams showing the results of measuring α wave power of ear electroencephalograms using the electroencephalogram measuring device of the embodiment. [Figure 14A] 14A(A), (B), and (C) are diagrams showing the results of measuring the SSVEP component of an ear electroencephalogram using the electroencephalogram measuring device of the embodiment. [Figure 14B] 14B(A), (B), and (C) are diagrams showing the results of measuring the SSVEP component of an ear electroencephalogram using the electroencephalogram measuring device of the embodiment. [Figure 14C] 14C(A), (B), and (C) are diagrams showing the results of measuring the SSVEP component of an ear electroencephalogram using the electroencephalogram measuring device of the embodiment. [Figure 15] FIG. 15 is a diagram showing the accuracy (%) of the measured values ​​of the ear EEG in comparison with the accuracy (%) of the measured values ​​of the occipital EEG for each of the analysis algorithms LCCA, TRCA, LCCAR, and TRCAR. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, an embodiment of an electroencephalogram measuring apparatus according to the present invention will be described with reference to the drawings.

[0022] 1A and 1B are diagrams showing an electroencephalogram measuring apparatus 100 according to an embodiment.

[0023] The electroencephalogram measuring device 100 of the embodiment is composed of electroencephalogram measuring devices 100L and 100R which are attached to the left and right ears of a human being, respectively.

[0024] Fig. 1A shows an electroencephalogram measuring device 100L worn on a person's left ear, and Fig. 1B shows an electroencephalogram measuring device 100R worn on a person's right ear.

[0025] Fig. 1C shows a state in which the electroencephalogram-measuring device 100L is attached to a left ear 10EL of a person, and Fig. 1D shows a state in which the electroencephalogram-measuring device 100R is attached to a right ear 10ER of a person.

[0026] The electroencephalogram measuring devices 100L and 100R are symmetrical to each other. In the following, the electroencephalogram measuring device 100L will be described as a representative. In the following, the same components in the electroencephalogram measuring devices 100L and 100R will be given the same reference numerals and duplicated descriptions will be omitted. Only the components that should be distinguished between the electroencephalogram measuring devices 100L and 100R will be described.

[0027] The electroencephalogram measuring apparatus 100L includes an auricle surrounding contact member 110 and a holding member 120.

[0028] (Auricle surrounding contact parts)

[0029] 1A and 1B, the auricle-periphery contact member 110 is a member formed in a curved shape. The auricle-periphery contact member 110 is formed in a C-shape or a horseshoe shape in a plan view. The auricle-periphery contact member 110 can be made of, for example, a thermoplastic elastomer.

[0030] Hereinafter, the individual EEG measurement electrodes 131-135 (arranged in the EEG measurement apparatus 100L) and the EEG measurement electrodes 136-140 (arranged in the EEG measurement apparatus 100R) will be collectively referred to as EEG measurement electrodes 130.

[0031] The auricle peripheral contact member 110 has a length LS (shown by a dotted line in Figures 1A and 1B) along which five EEG measurement electrodes 131-135 (or EEG measurement electrodes 136-140) are arranged at a predetermined distance apart along the outer periphery 11C of the auricle 11.

[0032] Here, the predetermined distance between adjacent electroencephalogram measurement electrodes 130, 130 may be unequal distances or may be equal distances.

[0033] The auricular contact member 110 has a temporal bone contact surface 111 on which the five electroencephalogram measurement electrodes 130 come into contact with the region 20S of the skin 20 on the temporal bone around the auricle 11.

[0034] On the temporal bone contact surface 111, five electroencephalogram measurement electrodes 131, 132, 133, 134, and 135 are arranged at positions along the outer periphery 11C of the auricle 11 from the helical crus 12 to the earlobe 13.

[0035] Similarly, in the electroencephalogram measuring device 100R, five electroencephalogram measuring electrodes 136, 137, 138, 139, 140 are arranged on the temporal bone contact surface 111 at positions along the outer periphery 11C of the auricle 11 from the helical crus 12 to the earlobe 13.

[0036] Figures 3A and 3B show modified examples corresponding to Figures 1A and 1B, respectively. As shown in Figures 3A and 3B, the auricle peripheral contact member 110 may be formed in a ring shape. According to the modified example shown in Figures 3A and 3B, a plurality of electroencephalogram measuring electrodes 130 can be arranged around the entire circumference of the auricle 11.

[0037] (Electroencephalogram (EEG) measurement electrodes)

[0038] The electroencephalogram measuring electrode 130 is fixed to the temporal bone contact surface 111 by adhesive.

[0039] The electroencephalogram measurement electrode 130 detects the electric potential of a part where the electrode surface 130A is in contact with the electrode 130. As the electroencephalogram measurement electrode 130, for example, an electroencephalogram dish electrode (NE-116A manufactured by Nihon Kohden Corporation) can be used.

[0040] Note that any one of the electrodes 131-135 for measuring electroencephalograms (for example, the electrode 135 for measuring electroencephalograms) may be used as the reference electrode 130R1, and any one of the electrodes 136-140 for measuring electroencephalograms (for example, the electrode 140 for measuring electroencephalograms) may be used as the reference electrode 130R2. The reference electrode 130R1 may be provided separately from the electrodes 131-135 for measuring electroencephalograms, and the reference electrode 130R2 may be provided separately from the electrodes 136-140 for measuring electroencephalograms. The potentials Vr1 and Vr2 detected by the reference electrodes 130R1 and 130R2 are used as reference potentials for the potentials detected by the electrodes 131-135 for measuring electroencephalograms and the potentials detected by the electrodes 136-140 for measuring electroencephalograms. For example, in a digital electroencephalograph, a differential amplifier is used to record the electroencephalograms of each electrode with the reference electrode as a reference. For example, when determining a potential difference between a potential V1 detected by the EEG measurement electrode 131 and a potential V2 detected by the EEG measurement electrode 132, the potential difference ΔV is expressed as follows:

[0041] ΔV=(V1-Vr1)-(V2-Vr1)

[0042] As a result, the potential difference between the two electrodes can be determined with high accuracy.

[0043] The electroencephalogram measuring electrodes 130 are electrically connected to an electric signal line 150 that transmits a detection signal indicating a detected potential as an electric signal.

[0044] (holding member)

[0045] FIG. 2 is a diagram showing an example of the configuration of the holding member 120. As shown in FIG.

[0046] The holding member 120 is a member that holds the auricle surrounding contact member 110 at a position where the five EEG measurement electrodes 131 to 135 (or the five EEG measurement electrodes 136 to 140) abut against the region 20S of the temporal bone skin 20 around the auricle 11.

[0047] As shown in FIG. 2, the holding member 120 can be made of a conductive adhesive 121. The conductive adhesive 121 can be a commercially available conductive gel or conductive paste for electroencephalograph electrodes. The conductive adhesive 121 may have conductivity between the outer skin 20 on the temporal bone and the electroencephalogram measurement electrodes 130 and adhesiveness to the outer skin 20 on the temporal bone. The conductive adhesive 121 is interposed between the five electroencephalogram measurement electrodes 131-135 (or the five electroencephalogram measurement electrodes 136-140) and the outer skin 20 on the temporal bone. For example, a predetermined amount of the conductive adhesive 121 as a conductive gel or conductive paste for electroencephalograph electrodes is applied to the electrode surface 130A of each of the five electroencephalogram measurement electrodes 131-135 (or the five electroencephalogram measurement electrodes 136-140).

[0048] 1A, 1B, 1C, and 1D, as shown in these figures, the holding member 120 can be configured with a locking portion 112 provided on the auricle-periphery abutment member 110. The locking portion 112 is formed in a shape that can be locked to the inside of the auricle 11, for example, an inverted U-shape.

[0049] The holding member 120 of the embodiment includes both the conductive adhesive 121 shown in Fig. 2 and the locking portion 112 shown in Fig. 1A, Fig. 1B, Fig. 1C, and Fig. 1D. Note that it is also possible to configure the holding member 120 using only one of the conductive adhesive 121 shown in Fig. 2 and the locking portion 112 shown in Fig. 1A, Fig. 1B, Fig. 1C, and Fig. 1D.

[0050] (Measurement section (detection signal processing / arithmetic processing))

[0051] FIG. 4 is a functional block diagram of a measurement section 200 that performs detection signal processing, arithmetic processing, and the like based on the potentials detected by the electroencephalogram-measuring devices 100L, 100R shown in FIGS. 1A and 1B.

[0052] It is also possible to incorporate part of the functions of the measurement section 200 into the electroencephalogram measurement devices 100L and 100R.

[0053] As shown in FIG. 4, the measurement unit 200 includes a detection signal processing unit 210 and an arithmetic processing unit 230.

[0054] The detection signal processing unit 210 receives analog signals of the detection potentials V1 to V10 and Vr1, Vr2 of the electroencephalogram measurement electrodes 131 to 140 and the reference electrodes 130R1, 130R2 via the electric signal line 150, and converts them into digital signals of the detection potentials V1 to V10 and Vr1, Vr2, for example, digital values ​​of a predetermined number of bits (for example, 10 bits). At this time, a process is executed in which the digital signals of the detection potentials V1 to V10 and Vr1, Vr2 are associated with identification codes (hereinafter referred to as channel numbers) C1, C2, . . . C10 and Cr1, Cr2 that specify and identify the electrodes. The digital signals of the detection potentials V1 to V10 and Vr1, Vr2 associated with the channel numbers C1, C2, . . . C10 and Cr1, Cr2 are received by the calculation processing unit 230.

[0055] The arithmetic processing unit 230 executes arithmetic processing according to the purpose. For example, in the case of measuring SSVEP, statistical processing such as canonical correlation analysis (CCA) and task-related component analysis (TRCA) is executed based on digital signals for each of a plurality of channel numbers (a plurality of channels at distant locations, not close locations). The arithmetic processing unit 230 can be configured by a personal computer.

[0056] In Fig. 4, communication between the electroencephalogram-measuring devices 100L, 100R and the measuring unit 200 is performed using a wired electric signal line 150. However, an embodiment in which the wired electric signal line 150 is omitted is also possible. For example, wireless signals corresponding to digital signals of detected potentials V1 to V10 and Vr1, Vr2 associated with channel numbers C1, C2, ... C10 and Cr1, Cr2 may be transmitted from the electroencephalogram-measuring devices 100L, 100R to the measuring unit 200. Wireless communication can be performed using standards such as Ethernet (registered trademark), FDDI, Wi-Fi (registered trademark), and Bluetooth (registered trademark).

[0057] Figures 5A and 5B respectively show configuration examples corresponding to Figures 1A and 1B for performing wireless communication. Figure 5A shows a configuration example of an electroencephalogram-measuring device 100L for performing wireless communication. Figure 5B shows a configuration example of an electroencephalogram-measuring device 100R for performing wireless communication. The same components as those in Figures 1A and 1B are given the same reference numerals and duplicated explanations will be omitted.

[0058] As shown in FIGS. 5A and 5B, the electroencephalogram measuring apparatus 100L is equipped with a detection signal processing / communication processing module 160 including the functions of a communication processing unit 220 in addition to the detection signal processing unit 210 of the measuring unit 200.

[0059] An electric signal line 151 , which functions similarly to the electric signal line 150 , is electrically connected between the electroencephalogram measuring electrodes 131 to 135 and the reference electrode 130 R 1 and the detection signal processing and communication processing module 160 .

[0060] The electric signal line 151 may be embedded inside the auricle-periphery contact member 110 or may be disposed on the surface of the auricle-periphery contact member 110 .

[0061] Similarly, the detection signal processing / communication processing module 160 may be embedded inside the auricle contact member 110 or disposed on the surface of the auricle contact member 110 .

[0062] FIG. 6 is a functional block diagram of a measurement section 200 that performs arithmetic processing and the like based on wireless signals transmitted from the detection signal processing / communication processing module 160 of the electroencephalogram measurement devices 100L, 100R shown in FIGS. 5A and 5B.

[0063] As shown in FIG. 6, the measurement unit 200 is composed of a detection signal processing unit 210 and a communication processing unit 220 (detection signal processing / communication processing module 160) mounted on the EEG measurement device 100L, 100R, and a communication processing unit 240 and an arithmetic processing unit 230 provided in a location separate from the EEG measurement device 100L, 100R.

[0064] The communication processing unit 220 of the detection signal processing / communication processing module 160 executes a process of transmitting digital signals of the detection potentials V1 to V10 and Vr1, Vr2 associated with the channel numbers C1, C2,...C10 and Cr1, Cr2 as wireless signals in accordance with a predetermined communication protocol. The detection signal processing / communication processing module 160 is provided with a power supply and a start switch (not shown).

[0065] The communication processing unit 240 executes a process of receiving a wireless signal transmitted from the communication processing unit 220 mounted on the electroencephalogram-measuring devices 100L, 100R, and executes a process of sending the signal to the arithmetic processing unit 230.

[0066] (Example of use)

[0067] The electroencephalogram measuring apparatus 100L shown in FIG. 1A and the electroencephalogram measuring apparatus 100R shown in FIG. 1B are

[0068] As shown in Figs. 1C and 1D, the devices are attached to the left ear 10EL and right ear 10ER of the subject of electroencephalography measurement.

[0069] 4, the electroencephalogram measuring devices 100L, 100R and the measuring section 200 are electrically connected by a wired electric signal line 150. Then, the measuring section 200 is started so as to be able to execute detection signal processing and arithmetic processing, and the arithmetic processing section 230 measures alpha waves or SSVEP of the electroencephalogram measurement subject.

[0070] 5A and 5B may be attached to the left ear 10EL and right ear 10ER of the subject of electroencephalogram measurement. In this case, a start switch (not shown) of the detection signal processing and communication processing module 160 is turned on to make the detection signal processing and communication processing module 160 (detection signal processing unit 210, communication signal processing unit 220) ready to perform detection signal processing and communication processing. The communication processing unit 240 and the calculation processing unit 230 shown in FIG. 6 are started to make them ready to perform communication processing and calculation processing, respectively, to establish a wireless communication connection between the electroencephalogram measurement devices 100L, 100R and the measurement unit 200, and the calculation processing unit 230 measures alpha waves or SSVEP of the subject of electroencephalogram measurement.

[0071] An external device may be operated based on the measured SSVEP.

[0072] For example, software for estimating the intention of the electroencephalogram measurement subject based on the measured SSVEP, generating an operation command signal to an external device based on the estimation result, and outputting the operation command signal to the external device is installed in the arithmetic processing unit 230 (personal computer).The external device and the arithmetic processing unit 230 are then connected via, for example, a controller or actuator so that the external device operates in response to the operation command signal.

[0073] The external device is, for example, a personal computer or a wheelchair used by the electroencephalogram measurement subject. As a result, even if the electroencephalogram measurement subject is a person with a disability who has difficulty in communicating his / her intention to others, the arithmetic processing unit 230 can measure the SSVEP of the electroencephalogram measurement subject, estimate the intention of the electroencephalogram measurement subject based on the measured SSVEP, generate an operation command signal based on the estimation result, and operate the external device in response to the operation command signal. As a result, even a person with a disability can operate a personal computer or a wheelchair.

[0074] When worn, the electroencephalogram measuring devices 100L and 100R of the embodiments are partially hidden inside the auricle 11 and do not block the ear hole, as shown in Figures 1C, 1D, 3A, and 3B. Therefore, compared with conventional head electroencephalogram measuring devices and ear electroencephalogram measuring devices, they are less likely to be noticed by others and are easy to put on and take off and have a comfortable fit. Therefore, they are suitable for the above-mentioned daily use of constantly measuring electroencephalograms.

[0075] As shown in Figures 1C, 1D, 3A, and 3B, in the electroencephalogram measuring devices 100L and 100R of the embodiment, the auricle peripheral contact member 110 has a length LS along the outer periphery 11C of the auricle 11, at least from the helical crus 12 to the earlobe 13, in which a plurality of (e.g., five) electroencephalogram measuring electrodes 130 are arranged at a predetermined distance apart. This makes it possible to increase the number of electroencephalogram measuring electrodes 130 (e.g., 10 electrodes on the left and right), and to ensure a wide distance between the electrodes. This allows the SSVEP to be detected more accurately than in conventional ear electroencephalogram measuring devices.

[0076] Next, other embodiments of the electroencephalogram measuring apparatuses 100L and 100R will be described.

[0077] Fig. 7 is a diagram corresponding to Fig. 1A and shows another embodiment of an electroencephalogram measuring device 100L to be worn on the left ear of a human. An electroencephalogram measuring device 100R to be worn on the right ear of a human is configured symmetrically to Fig. 7, and therefore a description thereof will be omitted.

[0078] 8(A) is an exploded view of the components shown in FIG. 7, and FIG. 8(B) is a partial cross-sectional view of FIG.

[0079] 7 and 8, components having the same functions as those shown in FIGS. 1 to 6 are given the same reference numerals and descriptions thereof will be omitted as appropriate.

[0080] 7 and 8, the auricle peripheral contact member 110 includes a plurality of connecting members 101A, 101B, 101C, 101D, and 101E that are connected so as to be deformable into a shape corresponding to the shape of the outer periphery 11C of the auricle 11. The connecting members 101A, 101B, 101C, 101D, and 101E are collectively referred to as connecting members 101.

[0081] The connecting member 101 itself is made of a material that is flexible and can be shaped to correspond to the shape of the outer periphery 11C of the auricle 11, such as a thermoplastic elastomer.

[0082] In the embodiment shown in Figures 7 and 8, the connecting members 101 are connected to each other so that the shape can be changed to match the shape of the outer periphery 11C of the auricle 11, but this is just one example, and the auricle peripheral abutment member 110 may be formed from a single member and bendable to a shape that matches the shape of the outer periphery 11C of the auricle 11.

[0083] For example, the auricle-periphery contact member 110 may be made of an elastic material such as a thermoplastic elastomer or silicone rubber, so that it can bend to a shape corresponding to the shape of the outer periphery 11C of the auricle 11. In addition, the auricle-periphery contact member 110 may be made of a bellows or the like, so that it can bend to a shape corresponding to the shape of the outer periphery 11C of the auricle 11.

[0084] Returning to Figs. 7 and 8, the connecting members 101A, 101B, 101C, 101D and 101E are provided with electroencephalogram measuring electrodes 131, 132, 133, 134 and 135, respectively.

[0085] 7 and 8, a holding member 120 is provided on each electrode surface 130A of the electroencephalogram measurement electrodes 131, 132, 133, 134, and 135 in the same manner as in Fig. 2. The holding member 120 is, for example, a conductive adhesive 121 such as a conductive gel or a conductive paste for electroencephalogram electrodes, which is applied in a predetermined amount to the electrode surface 130A.

[0086] The connecting members 101A, 101B, 101C, 101D and 101E are each formed with a recess 116 for accommodating the electroencephalogram measurement electrodes 131, 132, 133, 134 and 135. Therefore, the electroencephalogram measurement electrodes 131, 132, 133, 134 and 135 can be accommodated without requiring an additional thickness in the thickness direction of the auricle surrounding contact member 110.

[0087] The connection portion 130C between the EEG measurement electrodes 131, 132, 133, 134, and 135 and the signal line 150 is housed in the notched recess 116C. Therefore, the EEG measurement electrodes 131, 132, 133, 134, and 135 can be positioned and fixed to the auricle surrounding contact member 110.

[0088] The ends 114U, 114L of the connecting members 101 can be connected to each other so as to be able to swing freely, for example, via a pin 113 having a split pin portion 113P as a shaft portion.

[0089] An end 114U of the connecting member 101A is positioned above an end 114L of the adjacent connecting member 101B, and a pin hole 115U of the connecting member 101A is positioned to match a pin hole 115L of the adjacent connecting member 101B. Then, an axis portion 113P of a pin 11 is inserted into the pin holes 115U and 115L. The legs of the split pin portion 113P as an axis portion are opened from the base to both sides, thereby connecting the connecting member 101A and the adjacent connecting member 101B. In the same manner, the ends 114U and 114L of the connecting members 101B, 101C, 101D, and 101E are connected to each other using the pin 113.

[0090] The auricle-periphery contact member 110 of the other embodiment configured in this manner can be thin in the thickness direction and does not take up much space, so that it is difficult for others to notice that the electroencephalogram measuring device 100L, 100R is being worn.

[0091] In addition, the auricle-periphery contact member 110 in another embodiment can be configured to be thin, so that the adhesive strength of only the conductive adhesive 121, such as a conductive gel or conductive paste for electroencephalograph electrodes, is sufficient to adhere to the outer skin 20 on the temporal bone and maintain the adhered state.

[0092] Furthermore, the auricle surrounding contact member 110 in another embodiment is flexibly deformed according to the size and shape of the human ear, so that it has excellent adhesion and the electroencephalogram measurement electrodes 130 do not float.

[0093] In addition, in the auricular contact member 110 of another embodiment, the number of electroencephalogram measurement electrodes 130 can be changed to a desired number by adjusting the number of connections of the connection members 101.

[0094] Furthermore, the auricle-periphery contact member 110 of another embodiment is highly versatile because it flexibly changes shape according to the size and shape of the human ear. This eliminates the need to prepare many different products according to the size and shape of the ear, and allows the electroencephalogram measuring devices 100L and 100R to be provided to the market at low cost.

[0095] Next, the measurement accuracy of ear EEG by the EEG-measuring devices 100L and 100R will be explained in comparison with a conventional head EEG-measuring device that measures brain waves at the back of the head.

[0096] Alpha wave measurement with eyes open and closed M1 and SSVEP measurement with a single stimulus M2 were performed by wearing a head EEG measuring device and an EEG measuring device 100 (100L, 100R) on the subject. Alpha waves are spontaneous EEGs (brain waves that humans constantly emit) in the frequency band of 8 to 13 Hz. Alpha waves are predominantly expressed in the occipital region when the subject is at rest or with the eyes closed. SSVEP is an induced EEG different from alpha waves, which are spontaneous EEGs, and as mentioned above, is a reaction that increases mainly in the occipital primary visual cortex when the subject gazes at a stimulus that flashes at a specific frequency.

[0097] Alpha wave measurement M1 with eyes open and closed was performed by measuring alpha waves with the eyes open for 5 sets of 10 seconds each, and measuring alpha waves with the eyes closed for 5 sets of 10 seconds each.

[0098] For SSVEP measurement using a single stimulus, M2, measurements of SSVEP were performed for each subject when the subject gazed at a flashing stimulus (flashing stimulus frequency), for 26 types of flashing stimuli (26 different stimulus frequencies), with 5 sets of measurements for 5 seconds with a 2-second interval as one set.

[0099] Since alpha waves are dominant when the eyes are closed compared to when they are open, we measured and evaluated the occipital and ear EEGs when the eyes were open and closed. In the alpha wave measurement M1 with the eyes open and closed, the EEG data was converted into frequency components using a fast Fourier transform (FFT), and the total power value from 8 to 13 Hz was taken as the alpha wave power.

[0100] SSVEP is generally observed in the 1-75 Hz range, with the amount of components peaking around 15 Hz. After the peak, the SSVEP components decrease, and in the high frequency range above 40 Hz, individual differences in signal-to-noise ratio and other parameters become large. In this measurement method, SSVEP was measured at stimulation frequencies in 2 Hz increments in the 10-60 Hz range, and differences between occipital and aural EEG were evaluated. The analysis algorithm mainly used was canonical correlation analysis (CCA).

[0101] Figures 9(A) and (B) show the alpha wave components of the occipital EEG of subject S.9 and the alpha wave components of the ear EEG of the same subject S.9, respectively. The horizontal axis of Figures 9(A) and (B) is frequency (Hz), and the vertical axis is potential (mV2). Eyes open is shown by a solid line, and eyes closed is shown by a solid line with a circle.

[0102] Figures 10(A) and (B) respectively show the alpha wave power of the occipital EEG of each subject S.1 to S.9 and the alpha wave power of the ear EEG of each subject S.1 to S.9. The horizontal axis of Figures 10(A) and (B) is each subject S.1 to S.9 (represented by numbers 1, 2, ..., 9 to identify the subjects), and the vertical axis is potential (mV2). Eyes open are indicated by hatching, and eyes closed are indicated by white.

[0103] The following can be seen from the graphs shown in FIGS. 9(A) and (B) and FIGS. 10(A) and (B).

[0104] That is, it was verified that the measurement level of the alpha wave signal was lower for ear EEG than for occipital EEG. Since ear EEG captures as a signal the brain waves propagating from the vicinity of conventional sites such as the occipital region, it was demonstrated that there is a certain level of attenuation compared to direct measurement of the occipital region. Although the absolute amount of components measured is greater for occipital EEG than for ear EEG, it was confirmed that there is a clear difference between the alpha wave components when the eyes are open and the alpha wave components when the eyes are closed.

[0105] Five out of nine subjects were found to have a statistically significant difference between the alpha wave power with eyes open and the alpha wave power with eyes closed. However, for all subjects, it was confirmed that the alpha wave power with eyes closed was greater than the alpha wave power with eyes open throughout the entire trial. From these measurement results, it is evaluated that the electroencephalogram measuring device 100 of this embodiment has the performance to clearly detect the alpha wave component.

[0106] 11(A) and (B) show the SSVEP component C of the occipital EEG of each subject S.1 to S.9 in comparison with the SSVEP component C of the ear EEG of each subject S.1 to S.9. The horizontal axis of FIG. 11(A) and (B) is the stimulation frequency (Hz), and the vertical axis is the SSVEP component C.

[0107] Figures 12 (A) and (B) respectively show the SSVEP increase ratio ratio of the occipital EEG of subject S.9 compared with the SSVEP increase ratio ratio of the ear EEG of the same subject S.9. The horizontal axis of Figures 12 (A) and (B) is the stimulation frequency (Hz), and the vertical axis is the SSVEP increase ratio ratio and the SSVEP component C. The SSVEP component C when there is no stimulation (normal state) is indicated by a triangle in the figure. The SSVEP component C when there is stimulation (when gazing) is indicated by a ● or ◯ in the figure. A ● indicates a case where there is a statistically significant difference between normal state and gazing state, and an ◯ indicates a case where there is no statistically significant difference between normal state and gazing state.

[0108] The SSVEP increase ratio is indicated by * in the figure. The SSVEP increase ratio ratio (*) is expressed as the value obtained by dividing the SSVEP component C with stimulation (● or ◯) by the SSVEP component C without stimulation (△) (● or ◯ / △).

[0109] The following can be seen from the graphs shown in FIGS. 11(A) and (B) and FIGS. 12(A) and (B).

[0110] In other words, it was verified that the measured level of the SSVEP component signal was smaller in the ear EEG than in the occipital EEG. This is for the same reason as in the case of alpha waves. It was also confirmed that the rate at which the SSVEP component decreased as the stimulation frequency increased was faster in the ear EEG than in the occipital EEG. Furthermore, in the occipital EEG, some subjects showed a significant increase in the SSVEP component C up to a stimulation frequency of 60 Hz, whereas in the ear EEG, the significant increase in the SSVEP component C was limited to a stimulation frequency of around 40 Hz.

[0111] Therefore, to construct an SSVEP-BCI using ear EEG, it is necessary to measure and then determine the available stimulation frequency band for each subject.

[0112] As described above, the signal levels of the measured alpha waves and SSVEP were smaller for ear EEG than for occipital EEG. However, the electroencephalogram measuring device 100 of the embodiment was able to detect alpha waves and SSVEP as clearly as the conventional head EEG measuring device, even for ear EEG.

[0113] Next, the influence of the conductive gel or paste used as the conductive adhesive 121 on the measurement accuracy will be described.

[0114] 13(A) and (B), like FIG. 10(B), show the results of measuring α wave power of ear electroencephalograms using the electroencephalogram-measuring apparatus 100 of the embodiment.

[0115] 13(A) and (B) respectively show a comparison of the alpha wave power of ear electroencephalograms when a paste is used for the conductive adhesive 121 and when a conductive gel is used for the conductive adhesive 121.

[0116] From the graphs shown in Figures 13(A) and (B), it can be seen that there is no significant difference in the measurement accuracy of alpha waves between when a paste is used as the conductive adhesive 121 and when a conductive gel is used, and that alpha waves can be clearly detected in both cases.

[0117] Figures 14A(A), (B), (C), Figures 14B(A), (B), (C), and Figures 14C(A), (B), (C), like Figure 12(B), show the results of measuring the SSVEP component of the ear electroencephalogram using the electroencephalogram measuring device 100 of an embodiment.

[0118] 14A(A), (B), (C), 14B(A), (B), (C), and 14C(A), (B), (C) respectively show the SSVEP increase ratio of the ear EEG for subjects S.1, S.2, S.3, S.4, S.5, S.6, S.7, S.8, and S.9. In the figures, the SSVEP increase ratio of the ear EEG when a paste is used for the conductive adhesive 121 is indicated by a circle, and the SSVEP increase ratio of the ear EEG when a conductive gel is used for the conductive adhesive 121 is indicated by an asterisk. The Reference Point, which is the reference value (1) of the SSVEP increase ratio, is indicated by a solid line.

[0119] From the graphs shown in Figures 14A(A), (B), (C), Figures 14B(A), (B), (C), and Figures 14C(A), (B), (C), it can be seen that when a paste is used as the conductive adhesive 121 and when a conductive gel is used, although the measurement accuracy of the SSVEP component is slightly inferior when a conductive gel is used, there is no significant difference in the measurement accuracy of the SSVEP component and in both cases the SSVEP component can be clearly detected.

[0120] Next, the effect of the analysis algorithm on the measurement accuracy will be described.

[0121] FIG. 15 shows the accuracy (%) of the measurement values ​​of ear EEG in comparison with the accuracy (%) of the measurement values ​​of occipital EEG for each of the analysis algorithms LCCA (Learning Canonical Correlation Analysis), TRCA (Task-Related Component Analysis), LCCAR (Learning Canonical Correlation Analysis with Reject), and TRCAR (Task-Related Component Analysis with Reject). These analysis algorithms LCCA, TRCA, LCCAR, and TRCAR are analysis programs based on CCA (Canonical Correlation Analysis) and TRCA (Task-Related Component Analysis). In the figure, the accuracy of the measurement values ​​of ear EEG is shown in white, and the accuracy of the measurement values ​​of occipital EEG is shown in hatching.

[0122] 15, it can be seen that when LCCAR and TRCAR are used as the analysis algorithms for calculation processing, the accuracy of the measurement value of the ear EEG is as high as that of the measurement value of the occipital EEG. Therefore, by applying both CCA (Canonical Correlation Analysis) and TRCA (Task Related Component Analysis) to the EEG measurement device 100 of the embodiment, it is possible to detect the ear EEG with high accuracy. [Explanation of symbols]

[0123] 100, 100L, 100R EEG measuring device 110 Auricular contact member 111 Temporal bone contact surface 130 Electrode for measuring electroencephalogram 120 Retaining member 121 Conductive adhesives 112 Locking part

Claims

1. a peripheral auricle contact member having a plurality of electroencephalogram measuring electrodes arranged at a predetermined distance apart along the outer periphery of the auricle, the plurality of electroencephalogram measuring electrodes being provided with a temporal bone contact surface that contacts the outer skin of the temporal bone around the auricle; a holding member for holding the auricular contact member at a position where the plurality of electroencephalogram measuring electrodes are in contact with the outer skin of the temporal bone around the auricle; An electroencephalogram measuring device equipped with

2. the plurality of electroencephalogram measuring electrodes are disposed at each position along the outer periphery of the auricle from the crus helicalis to the earlobe, The auricle-periphery contact member is formed in a curved shape. The electroencephalogram measuring apparatus according to claim 1 .

3. The auricle-periphery contact member is formed in a ring shape. The electroencephalogram measuring apparatus according to claim 1 .

4. the holding member is a conductive adhesive having electrical conductivity between the outer skin on the temporal bone and the electroencephalogram measurement electrode and adhesiveness to the outer skin on the temporal bone, The conductive adhesive is interposed between the electroencephalogram measurement electrode and the outer skin on the temporal bone. The electroencephalogram measuring apparatus according to claim 1 .

5. The auricle-periphery contact member includes a locking portion that is locked to an inner portion of the auricle, The locking portion constitutes the holding member. The electroencephalogram measuring apparatus according to claim 1 .

6. The auricle-periphery contact member is made of a material that is flexible to a shape corresponding to the outer peripheral shape of the auricle, or is made of a plurality of connecting members that are connected so as to be able to change their shape to a shape corresponding to the outer peripheral shape of the auricle.

2. An electroencephalogram measuring apparatus according to claim 1.

7. The auricle-periphery contact member is configured by connecting a plurality of connecting members together, The connecting members are each provided with the electroencephalogram measurement electrodes and the holding members.

7. An electroencephalogram measuring apparatus according to claim 6.

8. A recess for accommodating the electroencephalogram measurement electrode is formed in the connecting member.

8. An electroencephalogram measuring apparatus according to claim 6 or 7.

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