JP2009034404A - Method and apparatus for detecting brain function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for detecting brain function, which is capable of detecting information on a flow of a nervous signal in the brain at a spatially and temporally high resolution. <P>SOLUTION: This brain function detection apparatus includes a magnetic field generation magnet 1 for generating a static magnetic field environment, an ultrasonic generator 2 for generating ultrasonic waves, a transducer 3 for converting an electric signal from the ultrasonic generator 2 into ultrasonic waves and transmitting them, an electromagnetic sensor 4 for detecting electromagnetic waves generated by a subject 9 related to the given ultrasonic waves, a signal amplifier 5 for amplifying the electromagnetic signal detected by the electromagnetic sensor 4, a stimulation generator 6 for giving the stimulation to the subject 9, and a monitor 7 for displaying, for example, an image as the stimulation from the stimulation generator 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a brain function detection method and apparatus using a Lorentz force, and a biological information detection apparatus.

  Conventionally, as a method for measuring brain function, non-invasion methods such as functional MRI (fMRI), electroencephalogram (EEG), magnetoencephalogram (MEG) and the like are used. fMRI has a time resolution on the order of seconds, and EEG and MEG have a time resolution of several tens of ms, but a spatial resolution of several centimeters.

  The flow of brain signals proceeds in a few ms to a few hundred ms, and there is a limit in investigating temporal functions of brain functions, connectivity, and the like by the above-described methods. This is true not only for the brain but also for information relating to general living tissue.

  Accordingly, an object of the present invention is to provide a brain function detection method and apparatus capable of detecting information related to the flow of nerve signals in the brain with high spatial or temporal resolution. Another object of the present invention is to provide a biological information detection apparatus capable of detecting information related to a general biological tissue not limited to the brain with high spatial and temporal resolution.

  The purpose is to apply an ultrasound focused on a functional site to be measured in the brain from the head of the subject in a magnetic field, to give at least one stimulus related to the five senses to the subject, and to generate in relation to the ultrasound. This is achieved by a brain function detection method in which an electromagnetic wave to be detected is detected in the head of a subject and information on the flow of a nerve signal in the brain is obtained based on the detected signal.

  In addition, the object is to provide a magnet for generating a magnetic field, a vibrator for transmitting ultrasonic waves, an electromagnetic wave sensor for detecting electromagnetic waves generated in association with the ultrasonic waves, and a stimulus for applying stimulation. And a brain function detection device that obtains information on the flow of a nerve signal in the brain based on a signal detected by the electromagnetic wave sensor.

  Still another object is to provide a magnet for generating a magnetic field, a vibrator for transmitting ultrasonic waves, and an electromagnetic wave sensor for detecting electromagnetic waves generated in association with the ultrasonic waves, This is achieved by a biological information detection device that obtains information related to the biological tissue by detecting electromagnetic waves generated in relation to the ultrasonic waves in the biological tissue that is included by the electromagnetic wave sensor.

  ADVANTAGE OF THE INVENTION According to this invention, the brain function detection method and apparatus which can detect the information regarding the flow of the nerve signal in a brain with high resolution spatially or temporally can be obtained. In addition, it is possible to detect information related to a general biological tissue not limited to the brain with high spatial and temporal resolution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the principle of the present invention will be described.

  In the present invention, a static magnetic field and ultrasonic waves are used to detect brain function. The subject is placed in a static magnetic field environment, an ultrasonic focus is applied to the functional site to be measured, and vibrations are applied to ions (cations and anions) in the functional tissue at a constant frequency. Here, the functional site that can be measured is not limited as long as it is a site where nerve cells and nerve fiber ions exist such as cerebral cortex, but considering the attenuation of ultrasound, the brain such as visual cortex, auditory cortex, sensory cortex, etc. It can be said that the functional part located on the surface of the surface is easy to measure.

  Since normal ions inside and outside the cell are mixed with cations and anions, they are neutral or weak in potential. If there is no cell activity, the resting potential is maintained. On the other hand, Lorentz force acts on the ions due to the motion of the magnetic field and ions. The physical motion imparted to the ions is in the same direction, but the Lorentz force is exactly opposite for cations and anions. Therefore, in an environment without a magnetic field or vibration, even if cations and anions are mixed and are electrically neutral, a Lorentz force locally generates a higher potential than the normal state. In addition, when the ions are vibrated, the electric potential varies depending on the vibration frequency, so that an electromagnetic wave (electromagnetic field) is generated.

  The generated electromagnetic wave is measured on the brain surface with a detector having an induction coil or an electrode. Its signal frequency and amplitude depend on the applied ultrasonic signal. In such a state, a specific stimulus is given that is expected to be processed by the functional site. Then, the part is activated by the stimulation. Activation of the part, that is, nerve activity changes the state of ions in the tissue, and changes the steady electromagnetic wave waveform when there is no stimulation. The change is detected by a detector. This makes it possible to detect information related to the flow of nerve signals in the brain with high spatial and temporal resolution.

  Here, the spatial resolution is determined by the frequency of the ultrasonic wave to be used. When the propagation speed of the soft tissue of the living body is considered to be 1500 m / s, for example, if a 1 MHz ultrasonic wave is used, a spatial resolution of about 1.5 mm can be obtained. it can. If higher frequency ultrasonic waves are used, a spatial resolution of 1 mm or less can be obtained. However, since the signal attenuation increases as the frequency increases, it is necessary to devise an ultrasonic irradiation method such as dispersive arrangement of ultrasonic transducers (for example, “Focusing and steering through ablating and aberration layers: Application to ultrasonic”). propagation through the skull "M. Tanter et al J. Acoust. Soc. Am. 103 (5) pp. 2403-2410).

  In addition, the time from when the stimulation is started until the electromagnetic wave changes is the time taken for the signal to reach the functional site (latency time). This is the time resolution. By changing the frequency of the ultrasonic wave, a time resolution up to several hundred microseconds can be obtained, and the flow of signals in the brain can be accurately detected. That is, the propagation speed of the sound wave in the soft tissue of the living body is 1500 mm / ms when calculated as about 1500 m / s, and when the reciprocation distance from the epidermis of the head to the center is 300 mm, the ultrasonic wave makes one reciprocation in about 200 microseconds. That is, it is possible to detect a change that occurs in a time slower than 200 microseconds. Hereinafter, a brain function detection method according to the present invention will be described.

  FIG. 1 is a block diagram showing an embodiment of a brain function detection apparatus according to the present invention. In this embodiment, as shown in the figure, a magnetic field generating magnet 1 for generating a static magnetic field environment, an ultrasonic generator 2 for generating ultrasonic waves, and an electric signal from the ultrasonic generator 2 are converted into ultrasonic waves. A transducer 3 to be transmitted, an electromagnetic wave (electromagnetic field) sensor 4 for detecting an electromagnetic wave generated by the subject 9 in relation to a given ultrasonic wave, a signal amplifier 5 for amplifying an electromagnetic wave signal detected by the electromagnetic wave sensor 4, In addition, a stimulus generator 6 for applying a stimulus to the subject 9 and a monitor 7 for displaying an image as a stimulus from the stimulus generator 6 are provided. The computer 8 is connected to the ultrasonic generator 2, the signal amplifier 5, and the stimulus generator 6. The computer 8 issues a command related to ultrasonic generation to the ultrasonic generator 2, and generates a stimulus to the stimulus generator 6. And a signal obtained by the signal amplifier 5 is recorded.

  Although the stimulus generator 6 of this example displays an image on the monitor 7 as a stimulus, it is not limited to this. Depending on the functional site to be measured, a visual stimulus other than an image may be used, or other senses other than vision, that is, hearing, touch, smell, and taste may be used. The stimulus generator 6 can generate at least one stimulus related to these five senses.

  The operation of this embodiment is as follows. First, the subject 9 is placed in a static magnetic field environment by the magnetic field generating magnet 1. The vibrator 3 and the electromagnetic wave sensor 4 are installed on the skin of the head of the subject 9. The ultrasonic generator 2 generates a signal related to a specific position (functional part) in the brain that gives a desired frequency and a focal point of the ultrasonic wave in accordance with a command from the computer 8, and outputs the signal to the vibrator 3. On the other hand, the stimulus generator 6 gives a desired stimulus such as light or sound (an image displayed on the monitor 7 in this example) to the subject 9 in accordance with a command from the computer 8. The electromagnetic wave sensor 4 detects an electromagnetic wave generated by the vibration given by the magnet 1 and the vibrator 3. The detected electromagnetic wave signal is amplified by the signal amplifier 5 and recorded in the computer as information on the flow of the nerve signal in the brain. The information recorded in the computer can be displayed on a display device (not shown) through a predetermined process. Information relating to the flow of nerve signals in the brain is detected as follows, for example.

  FIG. 2 is a diagram illustrating an example of an ultrasonic input signal generated from the vibrator 3 by a signal from the ultrasonic generator 2. The horizontal axis is milliseconds (ms), and the frequency of the ultrasonic input signal in this example is 100 KHz.

  FIG. 3 is a diagram illustrating an example of an image signal displayed on the monitor 7 as a stimulus from the stimulus generator 6. In this example, the image stimulus start time is set to 0, and the image signal is given for a period of 10 ms. By showing the image for a period of 10 ms, the nerve cells in the visual cortex are activated during that time.

  FIG. 4 is a diagram illustrating an example of an electromagnetic wave signal detected by the electromagnetic wave sensor 4. The horizontal axis is milliseconds (ms), and the frequency of the electromagnetic wave signal in this example is 100 KHz.

  It can be seen from the waveform of the electromagnetic wave signal shown in FIG. 4 that suppression (or change) appears in the electromagnetic wave signal 50 ms after the start of stimulation. Thereby, it can be estimated that the propagation time of the signal to the measurement site is 50 ms. Thus, for example, the time taken to reach the measurement site from the eyes can be obtained from the time from the stimulation start time to the recorded change time of the electromagnetic wave signal.

  As shown in FIG. 4, the reason why a change appears in the electromagnetic wave signal 50 ms after the start of stimulation is that the ion polarization state when there is no stimulation is changed by the movement of ions into and out of the cell membrane caused by the activity of nerve cells by the stimulation. Because. Here, it is assumed that the movement of ions moves in the direction perpendicular to the polarization. In this example, a spatial resolution of about 15 mm can be obtained because an ultrasonic input of 100 KHz is used, but higher resolution can be obtained by using a higher frequency one.

  As described above, information related to the flow of nerve signals in the brain can be detected with high spatial or temporal resolution. In addition, a biological information detection apparatus can be obtained with the same configuration as the brain function detection apparatus. In this case, the stimulus generator is not necessarily required, and a certain magnetic field and ultrasonic waves are applied to the biological tissue containing ions, and electromagnetic waves generated in the biological tissue in relation to the ultrasonic waves are measured for a certain period of time. For example, since a change in potential due to nerve activity of the living tissue is reflected in the electromagnetic wave, a component due to nerve activity is extracted from the collected electromagnetic wave. A stimulus generator can also be used as needed. As a result, information relating to the living tissue can be detected with high spatial or temporal resolution. Here, information related to biological tissue is, for example, information transmission of nerve cells in vitro (outside biological conditions), a difference between normal tissue and abnormal tissue, or a signal from a motor nerve (spinal nerve) to muscles Information related to transmission.

  The present invention relates to a brain function detection method and apparatus using Lorentz force and a biological information detection apparatus, and has industrial applicability.

It is a block diagram which shows one Example of the brain function detection apparatus which concerns on this invention. It is a figure which shows an example of the ultrasonic input signal generated from a vibrator | oscillator by the signal from an ultrasonic generator. It is a figure which shows an example of the image signal displayed on a monitor as a stimulus from a stimulus generator. It is a figure which shows an example of the electromagnetic wave signal detected by the electromagnetic wave sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic field generator 2 Ultrasonic generator 3 Vibrator 4 Electromagnetic wave sensor 5 Signal amplifier 6 Stimulus generator 7 Monitor 8 Computer 9 Test subject

Claims (3)

  An ultrasonic wave focused on the functional site to be measured in the brain is given from the head of the subject in a magnetic field, at least one stimulus related to the five senses is given to the subject, and an electromagnetic wave generated in association with the ultrasonic wave is given to the subject. A method for detecting brain function, comprising: detecting information on a neural signal flow in the brain based on the detected signal.   A magnet for generating a magnetic field, a vibrator for transmitting ultrasonic waves, an electromagnetic wave sensor for detecting electromagnetic waves generated in association with the ultrasonic waves, and a stimulus generator for giving a stimulus An apparatus for detecting brain function, wherein information relating to a flow of a nerve signal in the brain is obtained based on a signal detected by the electromagnetic wave sensor.   A magnet for generating a magnetic field, a vibrator for transmitting an ultrasonic wave, and an electromagnetic wave sensor for detecting an electromagnetic wave generated in association with the ultrasonic wave, the ultrasonic wave in a biological tissue containing ions A biological information detection apparatus, wherein information relating to the biological tissue is obtained by detecting an electromagnetic wave generated in connection with the electromagnetic wave with the electromagnetic wave sensor.

Images