JPH0767848A - Biomagnetism measuring instrument and biomagnetism measuring method - Google Patents

Abstract

PURPOSE:To increase the detection output of biomangetism by providing a superconducting quantum interference element fluxmeter for detecting the slight magnetic fields according to the transmission of the nerve signal generated in the living body with a pickup coil in such a manner that the magnetic flux lines of the slight magnetic fields perpendicularly penetrate the coil plane of this pickup coil. CONSTITUTION:This biomagnetism measuring instrument has a magnetic shielding room and is provided with an electric stimulating device outside this magnetic shielding room. Surface electrodes 5, 5 for mounting on the surface of the living body and more particularly the finger tips 9 of the human body are connected to the front end of a wiring 3 inserted into the magnetic shielding room. A cylindrical magnetic shielding cover 6 is so disposed as to cover a part of the living body mounted with these surface electrodes 5, 5. The magnetic shielding room is internally provided with the superconducting quantum interference element (SQUID) fluxmeter 8 freely movably vertically and laterally. This fluxmeter 8 is so disposed that the pickup coil for detecting the magnetic fluxes built in a cylindrical measuring section 8a has a perpendicular plane when this measuring section 8a is arranged perpendicularly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a weak magnetic field in a living body, and more particularly, to an apparatus and a method suitable for basic research on a nerve transmission system of a living body.

[0002]

2. Description of the Related Art Conventionally, as a technique for basic research of a neurotransmission system such as the determination of a cut point of a neural network of a living body, a normal magnetic substance such as permalloy is used to reduce the noise magnetic field generated from earth magnetism or electric equipment. A magnetic shield room that can be reduced to about / 1000 is constructed, and the magnetic field generated by the nerve signal transmission of the living body is detected inside the magnetic shield room by using a superconducting quantum interference device (SQUID) magnetometer. By the way, in order to generate a nerve signal in a living body, an appropriate place in the living body (for example, in the case of an animal, at the end portion of the neural network such as the tip of a limb)
It is necessary to intentionally add an electrical signal. Therefore, an electric stimulus generator is provided outside the magnetically shielded room, a wire is drawn from the electric stimulator into the magnetically shielded room, and is wired to a necessary part of the living body in the magnetically shielded room. A stimulating current is applied to the living body. Then, a nerve signal (weak magnetic field in the living body) generated by this energization passes through an appropriate portion until it reaches the brain through the nerve transmission network, for example, a joint where the nerve network passes through a portion relatively close to the surface of the living body. The weak magnetic field of the living body is detected by using a SQUID magnetometer in the back side portion of the.

[0003]

However, in such a conventional technique, since the biological weak magnetic field of the nerve signal detected by the SQUID magnetometer is extremely small, the magnetic field generated by the stimulation current for biological stimulation is generated. As a result of affecting the biological weak magnetic field, it often happens that the biological weak magnetic field to be detected cannot be accurately identified. That is, since the magnetic field generated by the stimulation current for biological stimulation is detected as large magnetic noise by the SQUID magnetometer, there is a problem that the biological weak magnetic field generated by the nerve signal is disturbed.

In addition, this kind of SQ for measuring a weak magnetic field in a living body
As one configuration example of the UID magnetometer, an SQUID magnetometer A including a cylindrical measuring unit a as shown in FIG. 15 is known. A pickup coil c is provided inside the measuring unit a of the SQUID magnetometer A, and a magnetic flux line B of a living body weak magnetic field generated in, for example, the arm U of the living body can be measured. The pickup coil c is composed of a superconducting ring including a superconducting element such as Josephson element. Etc.) to measure the magnetic field.

However, when the biological weak magnetic field generated in the arm U of the living body is measured by the pickup coil c of the conventional SQUID magnetometer A, the magnetic flux lines are parallel to the coil surface of the pickup coil c as shown in FIGS. 15 and 16. Since B penetrates, the number of magnetic flux lines penetrating the coil surface of the pickup coil c is extremely reduced, resulting in SQU as a detection signal.
There is a drawback that the output voltage of the ID magnetometer cannot be increased.

The present invention has been made in view of the above circumstances, and in biomagnetism measurement inside a magnetically shielded room or the like, a weak magnetic field in a living body caused by an extremely small nerve signal is detected using a superconducting quantum interference device magnetometer. In this case, it is possible to obtain a large detection signal, provide a device that can measure by reducing the influence of the magnetic field generated by the stimulation current that interferes with the measurement, and accurately measure the biological weak magnetic field without being affected by the stimulation current. It is an object of the present invention to provide a biomagnetic measurement method capable of measuring.

[0007]

In order to solve the above-mentioned problems, the present invention provides an electric stimulator for electrically stimulating a living body, and a weak magnetic field associated with nerve signal transmission generated in the living body by the electric stimulation. In a biomagnetism measuring device including a superconducting quantum interference device magnetometer for detecting, the superconducting quantum interference device magnetometer includes a pickup coil for detecting the weak magnetic field, and the magnetic flux lines of the weak magnetic field are coil surfaces of the pickup coil. The pickup coil is arranged so as to vertically penetrate through.

In order to solve the above-mentioned problems, a second aspect of the present invention is to provide a magnetic shield room capable of accommodating a living body, and an electric stimulator provided outside the magnetic shield room to generate a pulsed electric stimulating wave. A wire connected to the electric stimulator and drawn into the magnetic shield room, and a part of the wire attached to a part of the surface of a living body housed in the magnetic shield room. A surface electrode, a part of the living body to which the surface electrode is attached, a magnetic shield cover covering the surface electrode and a part of the wiring, and a part of the living body covered with the magnetic shield cover A superconducting quantum interference device magnetometer for measuring a weak magnetic field, wherein the superconducting quantum interference device magnetometer comprises a pickup coil for detecting the weak magnetic field, Serial in which the magnetic flux lines of the weak magnetic field formed by arranging a pick-up coil so as to penetrate the coil plane of the pickup coil vertically.

In order to solve the above-mentioned problems, the magnetic shield cover according to claim 1 or 2 comprises at least one of a ferromagnetic material and an oxide superconductor.

In order to solve the above-mentioned problems, a fourth aspect of the present invention applies pulsed electrical stimulation to a part of a living body, and superimposes a weak magnetic field of a living body caused by a nerve signal generated from the electrically stimulated portion with a superconducting quantum. In a biomagnetism measuring method of measuring with an interference element magnetometer, the electric stimulation part is covered with a magnetic shield cover and then electric stimulation is given, and a pulse magnetic field generated due to the electric stimulation is shielded from the superconducting quantum interference element magnetometer. In this state, the pickup magnetic field is measured by arranging the pickup coil so that the magnetic flux lines of the biological weak magnetic field penetrate the coil surface of the pickup coil of the superconducting quantum interference device magnetometer vertically.

[0011]

[Function] Electrical stimulation causes nerve signal transmission in the living body,
If the coil surface of the pickup coil is arranged perpendicularly to the magnetic flux lines of the weak magnetic field generated by this, the number of magnetic flux lines penetrating the pickup coil will increase compared to the case where the magnetic flux lines penetrate parallel to the coil surface. However, the output of the SQUID magnetometer as a detection signal is improved.

Further, since the part of the living body to which the electrical stimulation is applied, the wiring and the surface electrode can be covered with the magnetic shield cover, the electrical stimulation can be applied, so that the pulsed magnetic field generated by the pulsed electrical stimulation is blocked from the magnetometer. It is possible to measure the biological weak magnetic field without being affected by the pulsed magnetic field. If the measurement is performed without being influenced by the pulsed magnetic field and the coil surface of the pickup coil is arranged so as to vertically penetrate the magnetic flux line as described above, the detection signal can be increased and the measurement accuracy is further improved. Further, by forming the magnetic shield cover from at least one of a ferromagnetic material and an oxide superconductor, a sufficient magnetic shield effect can be obtained with the magnetic shield cover. Further, the magnetic shield cover may be composed of one of a ferromagnetic material and an oxide superconductor, or may be a combination of both.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a biomagnetism measuring device according to the present invention. In the figure, reference numeral 1 indicates a magnetic shield room produced by laminating plate materials made of a magnetic material such as permalloy, and reference numeral 2 indicates a magnetic field. The electric stimulator 2 provided outside the shield room 1 is shown. An exhaust hole 1a is formed on a side portion of the magnetic shield room 1, and a wiring 3 connected to an output part of the electrostimulator 2 is provided with the exhaust hole 1a.
Through the inside of the magnetically shielded room 1. The magnetically shielded room 1 is manufactured, for example, so that the internal effective space dimension is about 4.0 m × 3.0 m × 2.5 m. A doorway is provided on the side. In addition, the electrical stimulation device 2 described above is capable of passing a pulsed electric current for electrical stimulation, and is, for example, 2.0.
A current of about -2.5 mA can be generated in a pulse shape at intervals of 0.2-0.3 ms, and specifically, SEM-4201 manufactured by Nihon Kohden Co., Ltd. can be used.

On the other hand, surface electrodes 5, 5 for mounting on the surface of a living body are connected to the tip of the wiring 3 introduced into the magnetic shield room 1. These surface electrodes 5 are attached to the fingertips 9 of the human body as shown in FIG. 2 when, for example, researching or measuring the neural network of the human body. Specifically, NM-312S manufactured by Nihon Kohden Co., Ltd. can be used.

Further, a cylindrical magnetic shield cover 6 is provided so as to cover a part of the living body on which the surface electrodes 5, 5 are attached. The magnetic shield cover 6 has a cylindrical shape and is made of a ferromagnetic material such as permalloy. When the surface electrodes 5 and 5 are attached to the fingertip 9 of the human body, the fingertip 9
Is formed to a size that can cover the. When the mounting location of the surface electrode 5 is larger than the fingertip 9 or the like, the magnetic shield cover 6 may be formed larger than that shown in the figure. The magnetic shield cover 6 is composed of a tubular portion 6a made of a ferromagnetic material and an inwardly facing flange portion 6b formed in one opening of the tubular portion 6a, and a through hole inside the flange portion 6b. The part is formed in a size that allows the finger 9 of the living body to be inserted therethrough. The magnetic shield cover 6 is connected to the ground wire 7
Grounded by.

Furthermore, inside the magnetically shielded room 1,
A superconducting quantum interference device (SQUID) magnetometer 8 as shown in FIG. 3 or FIG.
The cylindrical measuring unit 8a at the tip of the SQUID magnetometer 8 can be directed to any part of the living body. This SQUID magnetometer 8 can use a normal commercially available one, and has a pickup coil for magnetic flux detection inside a cylindrical measuring portion 8a.
The magnetic flux passing through this pickup coil is detected. There are various types of SQUID magnetometers 8, but in this example, a pickup coil 10 having a Josephson element incorporated in a superconducting ring is provided and a magnetic field penetrating the pickup coil 10 is measured. belongs to. The pickup coil 10 of this example has a different configuration from that of a general apparatus, and when the cylindrical measuring unit 8a is arranged vertically, the pickup coil 1
It is arranged so that 0 is the vertical plane. For reference, the size of each part of the magnetic shield cover 6 when actually attached to the finger of the living body is shown in FIG.

Next, a case of measuring a weak magnetic field of a living body using the above-mentioned device will be described. In order to measure a weak magnetic field of a living body, the living body is housed inside the magnetically shielded room 1, and a part of this living body, for example, a fingertip 9 of an animal such as a human body, has surface electrodes 5, 5 as shown in FIG. Put on,
The fingertip 9 is covered with the magnetic shield cover 6. At this time, the magnetic shield cover 6 is inserted into the fingertip 9 with the flange portion 6b of the magnetic shield cover 6 on the base side of the finger, and the front end portions of the surface electrodes 5 and 5 and the wiring 3 are held by the magnetic shield cover 6. Cover up.

Next, as shown in FIG. 4, the SQUID is directed toward a part away from the fingertip 9, for example, an inner part of the elbow joint.
The measuring unit 8a of the magnetometer 8 is brought into contact while standing vertically. Next, the electrical stimulator 2 is operated to apply electrical pulse stimulation to the fingertip 9 of the living body, and the magnetic field generated by the nerve signal generated by this stimulation through the nerve transmission network is SQUID magnetometer 8
It is detected by the pickup coil 10 of. When this electric stimulation is given, the surface electrodes 5 and 5 generate a pulsed magnetic field, but since this pulsed magnetic field is shielded by the magnetic shield cover 6, the measurement result of the SQUID magnetometer 8 is adversely affected. There is no. Further, the flange portion 6b of the magnetic shield cover 6 is the SQUI of the magnetic shield cover 6.
Since the opening on the D magnetometer 8 side is narrowed, it is possible to efficiently shield the magnetic field leaking from this opening to the SQUID magnetometer 8 side.

From the above, the weak magnetic field generated by the nerve signal can be accurately captured and measured by the SQUID magnetometer 8 without noise. Further, as in the case described above, the magnetic flux lines B of the biological weak magnetic field generated from the arm of the biological body
Is oriented concentrically around the arm as shown in FIG. 3, so the magnetic flux line B penetrating the pickup coil 10 of the SQUID magnetometer 8 is oriented perpendicular to the coil surface, and penetrates the pickup coil 10. The number of magnetic flux lines generated increases, and the detection signal voltage can be increased correspondingly, which facilitates detection of the weak magnetic field in the living body. Therefore, according to the above-described measuring method, the weak magnetic field of the nerve transmission signal can be accurately captured in a noise-free state, which can be greatly useful for the analysis and analysis of the nerve transmission network of the living body and the nerve signal. Of course, according to the device of the present invention, it can be applied to inspect the cut portion of the nerve transmission network.

In the above description, an example in which the magnetic shield cover 6 is formed of a ferromagnetic material into a cylindrical shape has been described. However, the shape of the magnetic shield cover 6 is a part of a living body on which the surface electrodes 5 and 5 are attached. Any shape may be used as long as it can cover the above, and it is needless to say that various shapes other than the cylindrical shape can be adopted. The material forming the magnetic shield cover 6 is not limited to a ferromagnetic material, and may be an oxide superconductor or a combination of both. Therefore, it is possible to adopt an appropriate shape such as a double structure of a cylinder made of a ferromagnetic material and a cylinder made of an oxide superconductor.

FIG. 7 shows an example in which the magnetic shield cover is made of an oxide superconductor. In this example, the magnetic shield cover 11 has a cylindrical container body (cryostat) 12 having a double wall structure. A cylindrical shield cover body 13 made of an oxide superconductor is housed inside, and a container body 12 is filled with a refrigerant such as liquid nitrogen. The shield cover body 13 is composed of a tubular portion 13a and an inwardly facing flange portion 13b formed at one end thereof. The oxide superconductor forming the shield cover body 13 is made of Y ₁ Ba ₂ Cu ₃ O.
_7-x composition, (BiPb) ₂ Sr ₂ Ca ₂ Cu ₃ O _x composition, Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _x composition, etc. having a high critical temperature and cooled with liquid nitrogen It will be in a superconducting state. Since this oxide superconductor has a superconducting state, it exerts a Meissner effect and prevents the invasion of magnetic flux.
3 can be used as a magnetic shield material.

The magnetic shield cover 11 having the above-mentioned structure can be suitably used as a magnetic shield for measuring a weak magnetic field in a living body by using it in the same manner as the magnetic shield cover 6 described in the previous embodiment. The same effect as that of the embodiment can be obtained.

FIG. 8 shows an example in which the magnetic shield cover is composed of an oxide superconductor and a ferromagnetic material.
The magnetic shield cover 15 of this example includes a cylindrical shield cover body 17 made of an oxide superconductor inside a cylindrical container body 16 having a double-walled peripheral wall, and a shield cover sub-body made of a ferromagnetic material. The container 18 is housed so as to be doubled, and the inside of the container body 16 is filled with a refrigerant such as liquid nitrogen. The shield cover main body 17 is composed of a tubular portion 17a and an inward flange portion 17b formed at one end thereof. Even the magnetic shield cover 15 including the shield cover main body 17 and the shield cover sub-body 18 can be suitably used as a magnetic shield for measuring a biological weak magnetic field as in the previous embodiment, and is equivalent to the above-described embodiment. The effect can be obtained. In the magnetic shield cover 15 of this example, since it is cooled by a coolant such as liquid nitrogen, it is necessary to appropriately dispose a heat insulating material or the like so as not to harm the living body to be mounted by cold air.
In the drawing, the structure of these heat insulating parts is omitted.

FIG. 9 shows a second example of the SQUID magnetometer according to the present invention. The SQUID magnetometer 20 of this example is shown.
9 is an example in which three pickup coils 22 with their coil surfaces oriented vertically are provided in an aligned state inside the rectangular tube-shaped measuring unit 21, and as shown in FIG. A weak magnetic field can be measured. Since the SQUID magnetometer 20 of this example is provided with the three pickup coils 22, the biological weak magnetic field can be simultaneously detected at three locations, and the biological weak magnetic field can be measured over a wide range.

FIG. 10 shows a third example of the SQUID magnetometer according to the present invention. The SQUID magnetometer 3 of this example is shown.
In No. 0, the measuring unit 31 is formed in a columnar shape, and the distal end portion thereof is formed with the concave grooves 31a having a size capable of inserting most of the arm of the living body, and three groups are provided on both sides of the concave grooves 31a. Pickup coils 33 are provided, three pickup coils 34 are provided above the concave groove 31a, and a total of nine pickup coils are provided. The pickup coils 33 are arranged with their respective coil surfaces oriented horizontally, and the pickup coils 34 are arranged with their respective coil surfaces oriented vertically.

In order to use the SQUID magnetometer 30 having the above-mentioned structure, as shown in FIG. 10, the measuring section 31 is arranged so as to surround the arm of the living body with the concave groove 31a, and the weak magnetic field of the living body is generated in the same manner as described above. Used for measurement. Here, since the magnetic flux lines B due to the weak magnetic field in the living body are generated so as to surround the arm of the living body as shown in FIG. 10, the pickup coils 33, 34, ...
Are oriented perpendicularly to the direction of the magnetic flux lines B, high output can be obtained in any of the pickup coils 33, ..., And the weak magnetic field of the living body can be accurately detected.

[Test Example 1] An electric stimulator capable of generating a constant current pulse by using a magnetically shielded room in which permalloy plates are laminated to form an internal effective space dimension of 4.0 m × 3.0 m × 2.5 m SEM-4201 manufactured by Nihon Kohden Co., Ltd. was used. At the tip of the wiring connected to this electric stimulator, NM-3 of Nihon Kohden Kogyo Co., Ltd. was used as a surface electrode.
12S is connected and attached to the fingertip of the living body housed in the magnetic shield room, the tip of the wiring, the surface electrode and the fingertip are covered with a magnetic shield cover made of permalloy having the dimensions shown in FIG. 5, and the magnetic shield cover is grounded. Ground with a wire, then apply a current of 2.0-2.5mA to this fingertip, 0.2-0.3
A constant current pulse was applied at an interval of ms.

Further, the detecting portion of the SQUID magnetometer was attached to the inside of the elbow of the living body, and the weak magnetic field of the living body generated from the nerve transmission network was measured. In this elbow part, the right arm joint part was selected because the neural network passes through a part close to the surface of the living body and the signal is easy to identify. The pickup coil of the SQUID magnetometer was oriented vertically with respect to the arm of the living body, which was oriented substantially horizontally as shown in FIG. Further, for comparison, the magnetic shield cover is not attached to the fingertip and the surface electrode and the wiring are left exposed.
A test similar to the above was conducted with the pickup coil of the ID magnetometer oriented substantially horizontally. The above results are shown in FIG.
And shown in FIG.

FIG. 11 shows the result of measurement with the pickup coil oriented horizontally without mounting the magnetic shield cover, and FIG. 12 shows the result of measurement with the magnetic shield cover oriented vertically. When we measure the weak magnetic field in the living body without attaching the magnetic shield cover,
As shown in FIG. 11, the SQUID magnetometer is about 5000 fT
The pulsed magnetic field is detected, and the biological weak magnetic field itself, which should be detected after the pulsed magnetic field, is affected, and the waveform of the biological weak magnetic field is greatly distorted. On the other hand, when the magnetic shield cover was attached and measured, the pulse magnetic field measured by the SQUID magnetometer could be reduced to about 100 fT or less, and the influence of the pulse magnetic field could be reduced to 1/50 or less. . As a result, only the weak magnetic field in the living body could be measured as a clear waveform. Therefore, when the biological weak magnetic field caused by the nerve transmission signal is detected, it becomes difficult to be influenced by the pulse magnetic field, and the detection accuracy can be improved.

[Test Example 2] Next, (BiPb) ₂ Sr ₂ Ca
_A shield cover body made of an oxide superconductor having a composition of ₂ Cu ₃ O _x is shown in FIG. 7 as a container body (cryostat).
A magnetic shield cover, which was housed in and filled with liquid nitrogen (77K), was used, and the same test as in Test Example 1 was performed using this magnetic shield cover. The result is shown in FIG. As is clear from the result shown in FIG.
The magnitude of the pulse magnetic field detected by the QUID magnetometer is about 10
It became 0 fT or less, and as in Test Example 1, the influence of the pulse magnetic field could be reduced to 1/50 or less.

[Test Example 3] Next, a shield main body made of the above oxide superconductor and a shield cover by-product made of permalloy are shown in FIG. 8 as a container main body (cryostat).
A magnetic shield cover, which was housed in and filled with liquid nitrogen (77K), was used, and the same test as in Test Example 1 was performed using this magnetic shield cover. The result is shown in FIG. As is clear from the result shown in FIG.
The magnitude of the pulse magnetic field detected by the QUID magnetometer is about 10
It became 0 fT or less, and as in Test Example 1, the influence of the pulse magnetic field could be reduced to 1/50 or less.

[0032]

As described above, according to the device of the present invention, the nerve surface is transmitted to the living body by electrical stimulation, and the coil surface of the pickup coil of the SQUID magnetometer is applied to the magnetic flux lines of the weak magnetic field generated by the nerve signal transmission. If is arranged vertically, the number of magnetic flux lines penetrating the pickup coil increases more than when the magnetic flux lines penetrate parallel to the coil surface,
The output as a detection signal of the SQUID magnetometer is improved.
Therefore, the weak magnetic field in the living body can be easily detected.

Further, the apparatus of the present invention can cover the part of the living body to which the electrical stimulation is applied, the part of the wiring and the surface electrode with the magnetic shield cover, and then apply the electrical stimulation to the living body to measure the weak magnetic field of the living body by the magnetometer. The pulsed magnetic field generated by the pulsed electrical stimulation can be blocked from the superconducting quantum interference device magnetometer, and thus the weak magnetic field of the living body can be measured without being affected by the pulsed magnetic field.
Therefore, the accuracy of measurement of the biological weak magnetic field can be significantly improved, and the original waveform of the biological weak magnetic field having no magnetic noise component can be measured.

Further, by forming the magnetic shield cover from at least one of a ferromagnetic material and an oxide superconductor, a satisfactory magnetic shield effect can be obtained with the magnetic shield cover. The magnetic shield cover made of the ferromagnetic material is easy to handle and can be easily attached to the weak magnetic field measurement part of the living body. The magnetic shield cover may be composed of at least one of a ferromagnetic material and an oxide superconductor, or may be a combination of both. Therefore, it is possible to adopt an appropriate shape such as a double structure of a cylinder made of a ferromagnetic material and a cylinder made of an oxide superconductor.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a magnetically shielded room.

FIG. 2 is a perspective view showing a state in which a surface electrode and a magnetic shield cover are attached to a part of a living body.

FIG. 3 is a perspective view showing a positional relationship between a pickup coil of a SQUID magnetometer and a living body.

FIG. 4 is a perspective view showing an arrangement state of a SQUID magnetometer.

FIG. 5 is a cross-sectional view showing the structure of one example of the magnetic shield cover and the dimensions of each part.

FIG. 6 is a perspective view showing a state in which a surface electrode is attached to a part of a living body.

FIG. 7 is a cross-sectional view showing a second example of the magnetic shield cover.

FIG. 8 is a sectional view showing a third example of the magnetic shield cover.

FIG. 9 is a perspective view showing a second example of the SQUID magnetometer.

FIG. 10 is a perspective view showing a third example of the SQUID magnetometer.

FIG. 11 is a graph showing a measurement result of a magnetic field when the magnetic shield cover is not attached.

FIG. 12 is a graph showing measurement results when the first example of the magnetic shield cover is attached.

FIG. 13 is a graph showing a measurement result when the second example of the magnetic shield cover is attached.

FIG. 14 is a graph showing the measurement results when the third example of the magnetic shield cover is attached.

FIG. 15 is a perspective view showing a structure of a conventional SQUID magnetometer and an arrangement state with respect to a living body.

16 is a diagram showing a relationship between a pickup coil of the SQUID magnetometer shown in FIG. 15 and a magnetic flux line of a biological weak magnetic field.

[Explanation of symbols]

 1 magnetic shield room, 2 electric stimulus generator, 3 wiring, 5 surface electrode, 6, 11, 15 magnetic shield cover, 7 ground wire, 8 SQUID magnetometer, 10 pickup coil, 12 container body, 13, 17 shield cover body , 18 shield cover by-product,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masahiro Kojima, 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Shuji Yoshizawa 1-2-8, Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd.

Claims (4)

[Claims] 1. A biomagnetism measuring device comprising: an electric stimulator for electrically stimulating a living body; and a superconducting quantum interference device magnetometer for detecting a weak magnetic field accompanying nerve signal transmission generated in the living body by the electric stimulus, A superconducting quantum interference device magnetometer is provided with a pickup coil for detecting the weak magnetic field, and the pickup coil is arranged so that the magnetic flux lines of the weak magnetic field vertically penetrate the coil surface of the pickup coil. Magnetic measuring device. 2. A magnetic shield room capable of accommodating a living body, an electric stimulator provided outside the magnetic shield room to generate a pulsed electric stimulating wave, and the magnetic stimulator connected to the electric stimulator. Wiring drawn into the inside of the shield room, a surface electrode attached to a part of the living body attached to a part of this wiring and housed in the magnetic shield room, and a body electrode to which the surface electrode is attached A magnetic shield cover that covers a part of the surface electrode and the wiring, and a superconducting quantum interference device magnetometer that measures a weak magnetic field of a living body in a portion apart from a portion of the living body covered with the magnetic shield cover. The superconducting quantum interference device magnetometer comprises a pickup coil for detecting the weak magnetic field, and a magnetic flux line of the weak magnetic field is of the pickup coil. A biomagnetism measuring device, wherein a pickup coil is arranged so as to vertically penetrate the coil surface. 3. The biomagnetism measuring device according to claim 1, wherein the magnetic shield cover is made of at least one of a ferromagnetic material and an oxide superconductor. 4. A biomagnetism measuring method, wherein pulsed electrical stimulation is applied to a part of a living body, and a weak magnetic field in a living body caused by a nerve signal generated in response to the electrical stimulation is measured by a superconducting quantum interference device magnetometer. , The electrical stimulation portion is covered with a magnetic shield cover and then electrical stimulation is applied, and the pulse magnetic field generated due to the electrical stimulation is shielded from the superconducting quantum interference device magnetometer, and the magnetic flux lines of the biological weak magnetic field are provided. Is a method for measuring a weak magnetic field in a living body by arranging the pickup coil so as to vertically penetrate the coil surface of the pickup coil of the superconducting quantum interference device magnetometer.