JPH03297443A - Optical stimulation and induction cerebral magnetic wave measuring device - Google Patents

Abstract

PURPOSE:To enable optical stimulation with a clear light emission pattern and to change the light emission pattern arbitrarily by providing an optical stimulation device formed by a lot of selflight emitting elements having light emitting surfaces of a surface light emission pattern where alternately light is emitted in a close array, and providing a light emission pattern control device for the light emitting elements. CONSTITUTION:An optical stimulation device 6 disposed in front of a subject 5 is a pattern reversal stimulation device constructed so that red light emitting diodes which similarly have rectangular outer forms and one hundred of light emitting surfaces are arranged longitudinally and laterally ten by ten likes a checker board and the light emitting diodes of each line are alternately connected in a series five by five to be alternately turned on and off checkerwise. The light emitting timing of each selflight emitting diode in the optical stimulation device is switched by a light emission pattern control device 7 to form an arbitrary light emission pattern. Accordingly, a light emission pattern having satisfactory brightness and visibility on the light emitting surface can be obtained, and the switching can be performed at high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a light stimulation induced electroencephalogram measurement device, and particularly to a photostimulation-induced electroencephalogram measurement device, and particularly for measuring brain function among electroencephalography waves, which are minute biomagnetic fields generated from the human brain. This invention relates to a device for measuring optical stimulation-induced brain magnetic waves, which is necessary for physiological and basic medical research, diagnosis and treatment of neurological diseases, etc.

[Prior Art] Conventionally, X-ray tomography equipment (X-ray CT) and nuclear magnetic resonance imaging equipment (MRI) have been used as devices for imaging the inside of the human head.
), positron emission tomography (PET), etc., and these devices provide brain morphological information (X-ray CT, MHI) and biochemical metabolic information (PE).
T) is widely used as a powerful means for diagnosis and surgical treatment of brain diseases. However, with these means, it is impossible to directly measure electrical phenomena that form the basis of brain function.

In order to elucidate the superior brain functions of humans and to diagnose and treat neurological diseases such as epilepsy, it is necessary to record electrical phenomena in the brain. There is no commonly used method other than measurement.

However, since EEG measurement attempts to indirectly record electrical phenomena caused by nerve activity in the head by measuring the potential on the head surface using electrodes on the scalp, it is difficult to measure electrical phenomena caused by nerve activity in the head. Obtaining accurate information is difficult because of the substances in the front and in the head.

Electrodes are sometimes inserted into the brain to measure brain waves in order to directly record electrical activity in the head, but this method is not recommended for boat fishing due to the damage it causes to the living body and the danger it poses to the subject. It's almost never done.

In order to overcome these shortcomings of electroencephalogram measurement and obtain electrical information about biological activities accurately and non-invasively, in recent years, biomagnetic fields (brain waves and electroencephalograms) generated by neural activities in the head have been developed. Attempts are being made to directly measure the
As a concrete means of achieving this, we have developed a superconducting quantum interference device (SQUID), which is an ultra-sensitive magnetometer, and improved the 5QUID by introducing microfabrication technology developed in the semiconductor field. A magnetic wave measurement system was developed. As a result, the magnetic field is transmitted to the outside without being affected by intracranial tissues, and it is believed that this method can provide more useful information that directly reflects electrical activity in the head than electroencephalogram measurements.

By the way, brain waves and magnetic brain waves generated by the electrical activity of the human brain include those generated by spontaneous brain activity represented by alpha waves (basic rhythm), and those generated by specific stimuli applied from the outside (light, etc.). They can be divided into three types: those that occur as a response to (sound, electric shock, etc.) (evoked responses) and those that occur when a subject performs a certain type of exercise (exercise-related responses). Reactions are extremely important for clinical applications such as elucidating the superior characteristics of biological systems and identifying functional abnormalities in the nervous system. Therefore, a system for measuring electroencephalogram induced by light stimulation using several point light sources has been proposed. However, in the conventional induced electroencephalogram measurement system using optical stimulation, simple ON/OFF stimulation has been mainly performed by turning on and off at most a few point light sources as the optical stimulation device. However, as is known from research on light stimulus-evoked responses using electroencephalograms that has been conducted to date, the drawback of such on-off stimulation is that the illuminance of the light-emitting surface changes between on and off times. be.

Furthermore, it is expected that small point light sources such as those used in electroencephalogram measurements that have been reported so far do not provide effective stimulation to the visual nervous system and that no significant data will be obtained.

For this reason, pattern rehearsal stimulation is recommended for electroencephalogram measurement in order to eliminate these drawbacks caused by on/off stimulation of a point light source.

Figure 5 of the attached drawings shows an example of pattern reversal stimulation, which inverts the pattern on the grid.
The brightness of the entire light-emitting surface does not change in each cycle, and by changing the gaze point or changing the light-emitting part, it is possible to perform full-field stimulation or half-field stimulation, which individually stimulates the left and right nervous systems. can be stimulated.

Furthermore, a TV display is generally used as a light stimulation device used to measure light-evoked responses in brain waves.

In an attempt to use patterned monkey stimulation in electroencephalogram measurements, a slide projection device A was used to project a pattern onto a screen C in front of subject B, as shown in Figure 6, and subject B was exposed to optical stimulation indirectly. It has been proposed that the test be given to examiner B. In addition, in Fig. 6, D is 5QUID.
represents the system.

[Problems to be Solved by the Invention] By the way, in the conventionally proposed pattern reversal stimulation devices, the image is dark and unclear, so it is not an effective stimulation, and it takes at least +wlse to change the pattern.
There is a problem that it takes about 300 yen of time and is slow.

In addition, TV displays, which are generally known as optical stimulation devices used to measure light-evoked responses in brain waves, generate large magnetic field noise, and optical stimulation for electroencephalogram measurement systems that use 5QUID, which is a highly sensitive magnetic sensor. It cannot be used as a pattern display device.

Therefore, the present invention solves the problems of such conventionally proposed devices, can present a clear image with sufficient brightness, and has an i
It is an object of the present invention to provide a photostimulation-induced magnetoencephalography measurement device that can switch patterns at a high speed of 1 sec or less, can be used in combination with a biomagnetic field detection device, and can perform photostimulation using a light emission pattern.

Another object of the present invention is to provide a photostimulation-induced magnetoencephalogram measurement device that can solve the problem of magnetic field crosstalk from light emitting elements in a photostimulation device in processing induced signals.

[Means for Solving the Problems] In order to achieve the above first object, the first invention of the present invention provides a photostimulation device that performs photostimulation while switching light emission patterns, and a photostimulation device. In a photostimulation-induced electroencephalogram measurement device that is equipped with a signal processing device that processes signals induced in response to photostimulation, the photostimulation device or a surface-emitting pattern that is densely arranged and illuminated mutually. The optical stimulation device is composed of a large number of self-luminous elements each having a light-emitting surface, and is provided with a light-emitting pattern control device that switches the light-emitting timing of each self-luminous element in the optical stimulation device to form an arbitrary light-emitting pattern.

In addition, in order to achieve another object of the present invention, according to a second aspect of the present invention, there is provided a light stimulation device that performs light stimulation while switching light emission patterns, and a light stimulation device that responds to light stimulation by the light stimulation device. In the device to be measured for photostimulation-induced brain magnetism, the signal processing device includes a detection coil that detects a biomagnetic field generated in response to the photostimulation signal from the photostimulation device. , a device that converts the biomagnetic field detected by the detection coil into a voltage signal, and a low cutoff frequency that is less than 1/2 of the repetition frequency of the stimulation pattern by the optical stimulator, and a device that converts the biomagnetic field detected by the detection coil into a voltage signal. It consists of a filter device that removes noise, and an averaging device that adds and averages the voltage signal from which the noise has been removed by the filter device in synchronization with optical stimulation by the optical stimulation device.

Each light emitting element in the optical stimulation device may consist of a light emitting diode with a square light emitting surface.

[Function] In the first aspect of the present invention configured as described above, the optical stimulation device is configured with a large number of self-luminous elements having square light-emitting surfaces, and these light-emitting elements are arranged closely together. Since a surface emitting pattern is formed in which the lights are lit mutually, sufficient brightness can be obtained on the light emitting surface, and the range in which the brightness can be changed can be widened, thus providing optical stimulation with a clear light emitting pattern. Furthermore, the light emission pattern can be changed arbitrarily by changing the wiring and the light emission timing.

Further, in the second aspect of the present invention, the subject is given the required light stimulation by the light emission pattern by the light stimulation device, and when the visual stimulation signal is transmitted from the subject's retina to the visual cortex in the occipital region. A biomagnetic field is generated, this biomagnetic field is detected by a detection coil applied to the back of the subject's head, and the 5QUI
It is converted into a voltage signal by the circuit device D. Since this voltage signal includes transient noise when the optical stimulation device blinks, this noise is removed by the filter device.

By averaging the voltage signals from which noise has been removed in an averaging device in synchronization with optical stimulation by the optical stimulation device, minute optical stimulation-induced electroencephalographic waves can be detected.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3 of the accompanying drawings.

FIG. 1 schematically shows the configuration of a photostimulation-induced magnetoencephalogram measurement device according to an embodiment of the present invention. 20rT/JHz
It is placed in the cryostat 3 together with the S QU I D2 and cooled with liquid helium. The cryostat 3 is supported by a pedestal 4, and when in use, the pickup coil 1 is positioned close to an arbitrary position on the back of the head of the subject 5.

In addition, a light stimulation device 6 is arranged in front of the subject 5, and each light stimulation device 6 has one
5m+n x 15mm square shape with luminous surface power moon 4
It can be made up of 100 red light emitting diodes with a size of InI 11 x 14 InII+ arranged in rows of 10 vertically and horizontally in a grid pattern on a substrate, with every other row of 5 light emitting diodes connected in series, It is configured to flash alternately in a checkerboard pattern, thus forming a pattern reversal stimulator. 7 is a control unit that controls the operation of the optical stimulation device 6, and the blinking frequency of the optical stimulation device 6 can be arbitrarily set (
For example, f-111z), and a synchronization signal (for example, 2f=2Hz) synchronized with the optical stimulation by the optical stimulation device 6 is supplied to the averaging device 8.

Further, in FIG. 1, reference numeral 9 denotes a 5QUID2 circuit device, which converts the magnetic field signal detected by the pickup coil 1 into a voltage signal. The voltage signal generated by the circuit device 9 is supplied to the filter unit No.
is the lower cutoff frequency f to improve the signal/noise ratio.
+-0.5Hz high pass filter, high cutoff frequency fH-100tlz low pass filter, power supply noise cutoff frequency fN-51]Hz, 1[1[IHz,
]5DHZ... It is constructed as a comb-type filter. Further, the output side of this filter unit 10 is connected to an averaging device 8.

FIGS. 2 and 3 show examples in which optical stimulation-induced electroencephalographic waves were actually measured using the illustrated apparatus configured as described above. In this case, the distance between the light emitting surface of the optical stimulation device W6 and the eyes of the subject 5 is set to approximately 50 cm, and a point 5 cm above the external occipital tubercle of the subject 5 is set as the origin MO in FIG. Measured at the site.

The signals shown in Figures 2 and 3 are signals from which noise has been removed by averaging 100 times. Indicates signal strength. In addition, the lowest graph VEP in Figures 2 and 3 each shows the electroencephalogram, the remaining three graphs VEP each show the brain waves measured simultaneously, and the electroencephalogram graph L is the left occipital region shown in Figure 4. LO1 EEG graph M is at the center of the occipital region MO1 EEG graph R is at the right occipital region
This is an electroencephalogram measured at O. The measured left occipital LO and right occipital RO are 5c each on the left and right, centering on the center MO of the occipital region.
+n away, and a median frontal electrode 12 cm above the nasal root was used as the reference electrode.

In the measurement example shown in FIG. 2, the distance (-3
3 cm), and the measurement example shown in FIG. This is the case when measured at a position expressed by the coordinates of a distance along (3 cm, -3CI11).

These measurements indicate that clearly visually evoked electroencephalographic waves corresponding to electroencephalograms were measured.

Incidentally, in the illustrated embodiment, optical stimulation using pattern reversal stimulation has been exemplified as an optical stimulation device, but stimulation patterns other than pattern reversal stimulation can also be implemented by changing the blinking pattern of the light emitting elements.

Furthermore, although the description has been given using a light emitting diode as an example of a light emitting element, it is of course possible to use other self-emitting elements.

Furthermore, in the illustrated embodiment, the light emitting diodes can be constructed as a unit, and in that case, the stimulus color can be changed by replacing the light emitting diode unit with one that emits light of a different color.

[Effects of the Invention] As explained above, according to the first aspect of the present invention, a large number of self-luminous elements each having a light-emitting surface constituting a surface-emitting pattern that is closely arranged and lit mutually. The optical stimulation device is configured so that an arbitrary luminescence pattern can be formed by switching the emission timing of each self-luminous element in the optical stimulation device using a luminescence pattern control device, so that the luminescence surface has sufficient brightness and clarity. It is possible to obtain a light emission pattern with high intensity and to increase the switching speed, thereby providing an extremely effective optical stimulation means for an optical stimulation-induced electroencephalogram measuring device.

Further, the photostimulation-induced magnetoencephalogram measuring device equipped with the signal processing device according to the second aspect of the present invention solves the problem of crosstalk of the magnetic field from the light emitting element in the photostimulation device, and measures minute photostimulation-induced electroencephalograms. As a result, it becomes possible to easily detect biomagnetic brain wave signals that provide useful information for basic medicine, physiology, and clinical practice.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIGS. 2 and 3 are graphs showing examples of electroencephalogram signals together with brain waves measured using the apparatus shown in FIG. 1, and FIG. is a coordinate diagram showing the measurement position of the subject in the measurement examples of FIGS. 2 and 3,
FIG. 5 is a schematic diagram showing an example of pattern reversal stimulation, and FIG. 6 is a schematic diagram showing an example of a conventional photostimulation-induced electroencephalogram measuring device. Figure Middle detection coil (pickup coil) QUID Cryostat stand Subject optical stimulation device Light emission pattern control device Addition and averaging device 5 QUID circuit device Filter device Fig. 3 Fig. 2 Fig. 4

Claims (1)

[Claims] 1. A light source comprising a light stimulation device that performs light stimulation while switching light emission patterns, and a signal processing device that processes signals induced in response to light stimulation by the light stimulation device. In the stimulus-induced magnetoencephalogram measuring device, the optical stimulation device is composed of a large number of self-luminous elements having light-emitting surfaces that are arranged densely with each other and constitute a mutually illuminated surface-emitting pattern, and each self-luminous element in the optical stimulation device A photostimulation-induced electroencephalogram measuring device comprising a light-emission pattern control device that switches the light-emission timing of an element to form an arbitrary light-emission pattern. 2. The photostimulation-induced electroencephalogram measurement device according to claim 1, wherein each light-emitting element in the photostimulation device comprises a light-emitting diode having a rectangular light-emitting surface. 3. Photostimulation-induced electroencephalogram measurement device comprising a photostimulation device that performs photostimulation while switching light emission patterns, and a signal processing device that processes signals induced in response to photostimulation by the photostimulation device. , the signal processing device includes a detection coil that detects a biomagnetic field generated in response to a photostimulation signal from the photostimulation device, a device that converts the biomagnetic field detected by the detection coil into a voltage signal, and a signal processing device that detects a biomagnetic field generated in response to a photostimulation signal from the photostimulation device. A filter device has a low cut-off frequency of 1/2 or less of the pattern repetition frequency and removes transient noise when the optical stimulation device blinks, and a voltage signal from which noise has been removed by the filter device is used by the optical stimulation device. A photostimulation-induced electroencephalogram measuring device comprising: an averaging device that performs averaging in synchronization with optical stimulation.