JP2012239788A - Visual function controlling device, magnetic resonance imaging apparatus equipped with the visual function controlling device, magnetoencephalograph, and brain function measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a visual function controlling device enabling measurement of brain function associated with the visual function of a subject person under a prescribed measurement condition when carrying a device making measurement of the brain function of the subject person into operation by detecting change in magnetic field.SOLUTION: The visual function controlling device is used for controlling the visual function of the subject person when carrying the device making measurement of the brain function of the subject person into operation by detecting the change in magnetic field after presenting visual stimulation to the subject person. The visual function controlling device includes: a visual function controlling means including non-magnetic material for controlling the visual stimulation presented to the subject person; and a drive controlling means for controlling drive of the visual function controlling means.

Description

  The present invention relates to a visual function control device, a magnetic resonance imaging apparatus including the device, a magnetoencephalograph, and a brain function measurement method. In particular, the present invention relates to a visual function control device and a brain function measuring method used when implementing a device that measures a brain function of a subject by detecting a change in a magnetic field.

Visual functions such as visual acuity, eye movement ability, binocular vision ability, deep visual acuity (capability to correctly grasp perspective and stereoscopic effect), and visual information processing functions in the brain It is called a function.
However, in the present specification, in order to clarify the contents, the function relating to the former input is used as a visual function, and the information processing function in the latter brain is used as a brain function in the following description.
When this visual function and brain function work normally, humans can see things accurately.
In order to make the human visual function work normally, correction is also possible, and a typical example is glasses.
In this specification, a device that controls a human visual function such as glasses is defined as a visual function control device, and a function that is used to control a visual function such as a lens of glasses is defined as visual function control means.
In such a visual function control device, a technique for controlling the visual function when performing brain function measurement is not yet well known.

For brain function measurement, devices such as a magnetic resonance imaging (MRI) device and a magnetoencephalograph (MEG) are often used.
These are typical devices that measure brain function by detecting changes in the magnetic field. An MRI apparatus is an apparatus in which a static magnetic field is applied to a measurement site of a subject and a specific high-frequency magnetic field is further applied to obtain an image using a nuclear magnetic resonance phenomenon generated thereby.
A functional MRI (fMRI) method is known as a method for measuring brain function using this MRI apparatus.
The fMRI method gives subjects a variety of stimuli or tasks related to vision, touch, hearing, etc., and changes in the brain activity of the subjects caused by the stimuli and tasks (specifically, accompanying changes in cerebral blood flow) Measure magnetic field change). This is a method for evaluating the brain function of the subject.

However, the fMRI method has some limitations.
In the fMRI method, a very weak magnetic field change in the subject's brain is measured. For this reason, the MRI apparatus is installed in a magnetic shield room, and it is required that no instrument made of a magnetic material or an instrument that generates electromagnetic noise be brought into the shield room.
Therefore, in order to more accurately measure changes in brain activity related to the visual function of the subject by the fMRI method, a visual stimulus presentation method and a visual function control device that do not affect the magnetic field are required.

So far, as a visual stimulus presentation method performed when performing brain function measurement, Patent Literature 1 has proposed a stimulus presentation device to a subject for brain function measurement.
This device is a stimulus presentation device such as a monitor, a speaker, a screen, or the like, and includes the following means for presenting a plurality of stimulus forms within a predetermined time.
That is, means for causing the computer to rearrange the order at random, means for causing the computer to randomly determine the interval of stimulus presentation or the length of time for stimulus presentation, and causing the stimulus presentation device to output stimuli in that order. Means.

Also, as a visual function control method that is generally performed when brain function measurement is performed while presenting a visual stimulus to a subject, the subject is taken out of the apparatus and the visual function control means is exchanged whenever the measurement condition is changed. Techniques are known.
For example, the case where a lens capable of controlling the focus of the subject is used as the visual function control means will be described.
In this case, in order for the test subject to set an optimum lens for visually recognizing the visual stimulus, a process of taking the test subject out of the apparatus and replacing it with a lens having a different condition each time the measurement condition is changed is required.
Thereby, it becomes possible to measure brain function in a state where the subject's focus is in line with the visual stimulus.
That is, in general, it is possible to carry out brain function measurement related to visual function by unloading the subject outside the apparatus every time the measurement condition is changed and optimizing the visual function control means of the subject. It has become.

JP 2003-159253 A

However, the stimulus presentation device described in Patent Document 1 has the following problems.
In the stimulus presentation device, means for controlling the order and time of the stimulus to be presented to the subject is configured, but means for controlling the visual function of the subject is not included in the configuration in the device for performing brain function measurement. .
For this reason, it has been difficult to selectively control the visual function of the subject within the same measurement.
That is, it is difficult to perform brain function measurement in a state where the visual function of the subject is controlled within the same measurement.
Further, in the method of replacing the visual function control means every time the measurement conditions are changed, it is necessary to carry the subject out of the apparatus in order to replace the means.
Therefore, the measurement conditions of the fMRI method do not always match in each measurement performed by exchanging means.
Moreover, it is difficult to continuously change the condition of the visual function control means within the same measurement.

In view of the above problems, the present invention implements an apparatus for measuring a brain function of a subject by detecting a change in a magnetic field.
It is an object of the present invention to provide a visual function control device capable of measuring a brain function related to the visual function of a subject under certain measurement conditions, a magnetic resonance imaging apparatus including the device, a magnetoencephalograph, and a brain function measurement method.

The visual function control device of the present invention is used to control the visual function of the subject when the device for measuring the brain function of the subject is presented by presenting the visual stimulus to the subject and detecting the change of the magnetic field. A visual function control device,
Visual function control means comprising a non-magnetic material for controlling the visual stimulus presented to the subject;
Drive control means for controlling the drive of the visual function control means;
It is characterized by having.
The magnetic resonance imaging apparatus of the present invention includes the above-described visual function control device.
Moreover, the magnetoencephalograph of the present invention includes the above-described visual function control device.
Moreover, the brain function measuring method of the present invention includes:
Using a visual function control device comprising a visual function control means made of a non-magnetic material for controlling a visual stimulus presented to a subject, and a drive control means for controlling the drive of the visual function control means, A brain function measuring method for measuring a subject's brain function by detecting a change,
A first step of providing a state in which the visual function of the subject is controlled by using the visual function control means and the drive control means;
Acquiring a brain function image in the first step, and analyzing the brain function image;
It is characterized by having.

According to the present invention, when implementing a device for measuring a brain function of a subject by detecting a change in a magnetic field,
A visual function control device capable of measuring a brain function related to the visual function of a subject under a certain measurement condition, a magnetic resonance imaging apparatus including the device, a magnetoencephalograph, and a brain function measurement method can be realized.

The figure explaining the structural example of the visual function control apparatus in embodiment and Example 1 of this invention. The enlarged view explaining the structural example of the visual function control apparatus in Example 1 of this invention. The figure explaining the structural example of the visual function control apparatus in Example 2 of this invention. The figure explaining the structural example by the some visual function control apparatus in Example 2 of this invention. The figure explaining the sequence | arrangement regarding a test subject's visual function control and brain function image acquisition in Example 2 of this invention. The figure which shows the structure of the visual function control apparatus using the linear drive actuator in Example 3 of this invention. The figure explaining the structure of the magnetoencephalograph to which the visual function control apparatus in Example 4 of this invention is applied.

Visual function used to control the visual function of the subject when the visual function is presented to the subject in the embodiment of the present invention and the device for measuring the brain function of the subject is detected by detecting the change of the magnetic field. The control device
The visual function control means is composed of a non-magnetic material for controlling the visual stimulus presented to the subject and the drive control means for controlling the drive of the visual function control means. By doing so, it becomes possible to control the visual function of the subject within the device for measuring brain function.
Further, by using the visual function control device, the condition of the visual function control means of the subject can be selectively and continuously changed without taking the subject out of the device every time the measurement condition is changed.
Accordingly, by using the visual function control device of the present invention, it becomes possible to measure various brain functions related to the visual function of the subject under constant measurement conditions.
Specifically, for example, it can be configured as schematically shown in FIG.
Here, as an apparatus used for measuring a brain function of a subject by detecting a change in a magnetic field, an MRI apparatus and an MEG are exemplified.
In addition, when the brain function measurement is performed in the present embodiment, the means for presenting the visual stimulus to the subject may be any means as long as it does not affect the magnetic field.
For example, there is a means for presenting a visual stimulus to a subject by projecting an image or video using a projector and a non-magnetic screen.
Moreover, although the means etc. which show the visual stimulus by putting the real object which consists of a nonmagnetic material in front of a test subject's eyes etc. are mentioned, this invention is not limited to these.

As the visual function control means in the present embodiment, any means may be used as long as it has a configuration capable of controlling the presented visual stimulus in front of the subject's eyes and is made of a non-magnetic material.
A plurality of visual function control means may be provided in the visual function control device. When using a plurality of means, they may be constituted by means having different functions. The visual function control means is configured to be arranged in front of either the right eye or the left eye or both eyes.
In the present embodiment, the drive control means of the visual function control means may be anything as long as it is configured to control the position of the visual function control means, the rotational motion, and the like.
Position control of the visual function control means and switching control when using a plurality of visual function control means are possible by installing the drive control means in the visual function control means and thereby controlling the drive of the visual function control means become.
A plurality of these driving means may be provided.

In the above configuration, by using a visual function control device having a visual function control means and a drive control means made of a non-magnetic material, the visual function of the subject can be controlled within the device that performs brain function measurement.
In addition, by driving the visual function control means, the condition of the visual function control means of the subject can be selectively and continuously changed without taking the subject out of the apparatus every time the measurement condition is changed. Therefore, it is possible to measure various brain functions related to the visual function of the subject under constant measurement conditions.

Further, in the present embodiment, the visual function control means may be configured by any one or a combination of a lens, an eye shield, a polarizing plate, a neutral density filter, a prism, and a pinhole.
A plurality of these may be provided in the visual function control device. Moreover, when using a some means, you may be comprised by a different means.
In the above configuration, the following visual function control is possible by using any one or a combination of a lens, an eyepiece, a polarizing plate, a dark filter, a prism, and a pinhole as the visual function control means. Become.
For example, the visual acuity of the subject can be controlled by using a lens or a pinhole, and the binocular vision ability or deep visual acuity of the subject can be controlled by using an eye shield or a polarizing plate.
In addition, the visual function of the subject can be controlled by using a polarizing plate, a neutral density filter, and a prism. Specifically, it becomes possible to control the activity of nerve cells in the retina of the subject related to polarization characteristics and brightness.
Therefore, it is possible to always perform brain function measurement when these visual functions are controlled under constant measurement conditions.
In the visual function control device of this embodiment, the drive control unit may include an actuator made of a nonmagnetic material.
Among these, it is preferable that the ultrasonic motor is made of a non-magnetic material. A plurality of actuators may be provided. In the above configuration, when the drive control means is made of a non-magnetic material, the drive control means can be introduced into a device that performs brain function measurement.
That is, by using a non-magnetic actuator, it is possible to reduce the distance between the drive control means and the visual function control means, enabling precise control, and at the same time simplifying the visual function control device. It becomes possible.
In the present embodiment, a magnetic resonance imaging apparatus and a magnetoencephalograph equipped with the visual function control apparatus can be configured.
In the above configuration, when implementing a device for measuring a brain function of a subject by detecting a change in a magnetic field, it is possible to measure a brain function related to the visual function of the subject by using a visual function control device. It becomes.

In the present embodiment, the visual function control means made of a non-magnetic material for controlling the visual stimulus presented to the subject, and the drive control means for controlling the drive of the visual function control means. Using a function control device,
A brain function measuring method for measuring the brain function of a subject by detecting a change in a magnetic field can be configured as follows.
That is, a first step of providing a state in which the visual function of the subject is controlled by using the visual function control means and the drive control means;
The brain function measuring method including the second step of acquiring the brain function image in the first step and analyzing the brain function image can be specifically configured as follows.
In the step of providing a state in which the visual function of the subject is controlled by using the visual function control means and the drive control means, it is necessary to present a visual stimulus in order to control the visual function of the subject. At that time, it is preferable to present the visual stimulus without affecting the magnetic field.
Further, the state in which the visual function of the subject is controlled indicates a state in which the visual function of the subject when the brain function measurement is performed by presenting the visual stimulus is adjusted to the optimum condition for the purpose of the experiment. .
For example, when an experiment is performed using a lens as a visual function control means, an example of the purpose of the experiment is to perform a brain function measurement by presenting a visual stimulus in a state where the subject is most focused. .
At that time, in order to perform brain function measurement in accordance with the purpose of the experiment, it is necessary to selectively present to the subject several lenses having different frequencies, and to provide a lens that is most focused on the subject among them. is there.
The state in which the subject is most focused is the state in which the visual function of the subject is adjusted to an optimum condition for the purpose of the experiment.
Note that these steps are selectively and continuously performed in an apparatus for measuring brain function.

Also, in the step of acquiring the brain function image in the step and analyzing the image, when using an actuator for drive control, it is better to stop acquiring the brain function image while driving the actuator. preferable.
In the above process, by driving the visual function control means, the condition of the visual function control means of the subject can be changed selectively and continuously without taking the subject out of the apparatus each time the measurement condition is changed. Can do.
That is, it becomes possible to adjust the visual function of the subject when presenting the visual stimulus and performing the brain function measurement to the optimum condition for the purpose of the experiment while measuring the brain function.
When the lens is used as the visual function control means as in the previous example, it is possible to measure the brain function in a state where the subject is focused, and more accurately perform the brain function measurement related to the visual function of the subject. be able to.
In this way, various brain function measurements related to the visual function of the subject can always be performed under constant measurement conditions.
Moreover, since the brain function measurement when the visual function of the subject is controlled can be continuously performed, more accurate brain function measurement data can be obtained.
Further, in the step of providing the state in which the visual function of the subject is controlled, a plurality of controlled states having different properties can be periodically switched.
In the above process, by repeating a plurality of states in which the visual function is controlled at regular intervals, it becomes possible to perform image processing such as averaging of the obtained brain function image, and finally obtain a brain function image with less noise be able to.

Examples of the present invention will be described below.
[Example 1]
As Example 1, an example in which a visual function control apparatus is installed in an MRI apparatus and brain function measurement is performed will be described with reference to FIG. 1 which best represents the features of the present invention.
In this embodiment, a projector and a screen are used as the visual stimulus presenting means, and a lens is used as the visual function control means.
Accordingly, the condition of the visual function control means of the subject can be selectively and continuously changed without taking the subject out of the apparatus every time the measurement condition is changed.
In FIG. 1, 100 is an MRI apparatus, 101 is a subject, and 102, 103, 104, and 105 are a bed, a gradient magnetic field coil, a superconducting magnet, and a cylindrical measuring unit of the MRI apparatus, respectively.
In the above configuration, the subject 101 lies inside the cylindrical measuring unit 105, and the visual function control device 106 for controlling the visual function of the subject is installed in front of the subject. The visual function control device 106 includes a visual function control means 107 and an ultrasonic motor 108.
It is assumed that the visual function control means 107 and the ultrasonic motor 108 are made of a nonmagnetic material.
A controller (not shown) for controlling the driving of the ultrasonic motor 108 is installed in a magnetic shield room where the MRI apparatus is installed, and at a place having the maximum distance from the measurement position inside the MRI apparatus main body.
And it is connected with the ultrasonic motor 108 by the electromagnetically shielded control line.

As described above, the ultrasonic motor 108 is configured to be able to be driven and controlled via the controller when controlling the visual function of the subject.
Note that the ultrasonic motor 108 here is configured to be driven by a piezoelectric element (electro-mechanical energy conversion element) disclosed in many documents, such as JP-A-3-253272. Can be used.
In addition, a projector 109 for presenting visual stimuli to the subject 101 is installed outside the MRI apparatus 100.
A screen 110 for projecting an image projected from the projector 109 is installed in the apparatus. In addition, a mirror 111 for the subject 101 to view the screen 110 is installed in front of the subject's 101 eye.
In addition, the screen 110 and the mirror 111 shall be comprised with the material which does not contain a magnetic body.
An MR signal detection coil 112 is installed in the back of the subject 101 to detect an electromagnetic wave signal generated by a change in cerebral blood flow accompanying the nerve activity of the subject 101.
Here, in order to secure a visual field in front of the subject's eyes and to perform highly sensitive brain function measurement in the cerebral visual cortex (corresponding to the occipital region of the subject), the coil 112 uses a radio frequency coil of the surface coil type.

FIG. 2 is an enlarged view of the visual function control device 106 in this embodiment.
2A is an oblique projection, and FIG. 2B is a plan view. A plurality of visual function control means 107 are installed on the holding means 201 made of a non-magnetic material.
An ultrasonic motor 108 is attached to the back surface of the holding means 201. The rotating shaft of the ultrasonic motor 108 is connected to the center of the holding means 201, and the holding means 201 can rotate around this rotating shaft.

Next, a procedure for selectively and continuously changing the condition of the visual function control means of the subject in this embodiment will be described.
Here, it is assumed that the brain function related to the visual function of the subject is measured by using a lens as the visual function control means 107.
Specifically, as shown in FIG. 2B, four lenses 107 (A) to 107 (D) having different frequencies for correcting the visual acuity of the subject 101 are installed.
It is assumed that the lenses 107 (A) to (D) do not contain a magnetic material. The bed 102 is set so that the head of the subject 101 is placed on the cylindrical measurement unit 105 of the MRI apparatus 100.
Further, the visual function control device 106 is set in front of the eye of the subject 101 so that the trajectory 203 drawn by driving the ultrasonic motor 108 passes through the central axis of the eye of the subject 101.
After setting the device, the condition of the visual function control means is changed by the following procedure.

First, in step (1), the lens 107 (A) is fixed in front of the eye of the subject 101, and the subject 101 is caused to visually recognize the mirror 111 through the lens 107 (A).
Next, in step (2), the ultrasonic motor 108 is rotated, and control is performed so that the lens 107 (B) is fixed in front of the eye of the subject 101.
Next, in step (3), the lens 107 (B) is fixed in front of the eyes of the subject 101, and the subject 101 is caused to visually recognize the mirror 111 through the lens 107 (B). Next, in step (4), the ultrasonic motor 108 is rotated, and control is performed so that the lens 107 (C) is fixed in front of the eye of the subject 101.
By repeating the above steps and adjusting the lenses 107 (A) to (D) so as to be fixed in front of the eye of the subject 101, the test subject can be removed most of the time without changing the measurement condition. It is possible to select a lens that is in focus.
After taking these procedures into account, it is possible to accurately perform brain function measurement related to visual function by performing brain function measurement under conditions optimal for the subject.

In the above embodiment, the visual function control device 106 is used to control the visual function of the subject and to perform brain function measurement. However, the present invention is limited to such a configuration. It is not a thing.
For example, the shape of the visual function control means 107 is not limited to a circular shape, and a polygonal shape can also be used. Further, the shape is not limited to these shapes as long as the mirror 111 can be visually recognized through the visual function control means 107.
Further, in the present invention, the lenses 107 (A) to (D) for controlling the visual acuity of the subject 101 are used as the visual function control means 107, but if the visual function control means is made of a non-magnetic material, It is not limited to these. Eye shields, prisms, polarizing plates, neutral density filters, pinholes, etc. can be used.
The means for presenting the visual stimulus to the subject 101 includes means such as placing a real object made of a non-magnetic material in front of the subject's eyes, but is not limited to these as long as it does not affect the magnetic field. Absent.

[Example 2]
As Example 2, an example in which a visual stimulus is presented to a subject using a visual function control device will be described with reference to FIGS. 3, 4, and 5.
In this embodiment, an example will be described in which a chitomas stereo test, which is generally known as a stereoscopic examination, is performed together with brain function measurement by the fMRI method.
FIG. 3 is a drawing showing the features of the present invention as in FIG. 1. In FIG. 3, 301 is a test paper for performing a cytomass stereo test, and 302 is a polarizing plate as visual function control means. . The rest of the configuration is the same as in FIG.
For the test paper 301, a picture with the same composition, in which two pictures created with a little parallax are overlapped, is used.
One polarizing plate 302 having a 90-degree direction is prepared one by one, and each is placed in front of the left and right eyes of the subject.
The test content is only to visually recognize the test paper 301 through the polarizing plate 302.
If the subject 101 can view stereoscopically with no strabismus, the parallaxed portion can be viewed stereoscopically.
In the present embodiment, an example in which visual function control using a polarizing plate is performed and brain function measurement related to stereoscopic vision of a subject is performed in the chitomas stereo test will be described.
Note that the test paper 301 and the polarizing plate 302 are made of a nonmagnetic material.

Next, the procedure of the brain function measuring method by the fMRI method in this embodiment will be described.
Also in this embodiment, the same visual function control device 106 as that in the first embodiment is used. FIG. 4 is a diagram illustrating a configuration example including a plurality of visual function control devices 106 according to the present embodiment. Here, the polarizing plate 302 is used as the visual function control means.
Specifically, the same type of polarizing plate 302 is installed at two diagonal positions of the four visual function control means 107 shown in FIG. 4, for example, 107 (A) and 107 (C). To do.
In the visual function control devices installed in front of the left and right eyes, the polarizing plates 302 provided in the respective visual function control devices are used in which the polarization directions are shifted by 90 degrees.
Further, the visual function control means 107 (B) and 107 (D) are configured in a state in which nothing is provided in the present embodiment, that is, in the state of holes.
With the visual function control device 106 set, the bed 102 is set so that the head of the subject 101 is placed on the cylindrical measurement unit 105 of the MRI apparatus 100. Note that the visual function control device 106 is set so that the trajectory drawn by driving the ultrasonic motor 108 passes through the central axis of the eye of the subject 101.

Next, a sequence relating to visual function control and brain function image acquisition of the subject 101 in this embodiment will be described with reference to FIG.
First, the visual function control sequence of the subject 101 will be described with reference to FIGS.
In the following steps (1) to (5), the visual function of the subject 101 is controlled. FIG. 5A shows the order and time interval of each step, and FIG. 5B shows the positional relationship between the subject 101, the holding means 201, the test paper 301, and the polarizing plate 302 as the visual function control means.
In this embodiment, the visual function control devices installed in front of the left and right eyes are driven at the same timing.

First, in step (1), the visual function control means 107 on which the polarizing plate 302 is not installed is fixed in front of the eyes of the subject 101, and the test subject 301 is visually recognized during the time interval t1.
Next, in step (2), the ultrasonic motor 108 is rotated during the time interval t2, and control is performed so that the polarizing plate 302 is fixed in front of the eye of the subject 101.
Next, in step (3), the polarizing plate 302 is fixed in front of the eye of the subject 101, and the test paper 301 is visually recognized by the subject 101 through the polarizing plate 302 for the time interval t3.
Next, in step (4), the ultrasonic motor 108 is rotated during the time interval t4, and control is performed so that the visual function control means 107 without the polarizing plate 302 is fixed in front of the eye of the subject 101.
Next, in step (5), the visual function control means 107 on which the polarizing plate 302 is not installed is fixed in front of the eyes of the subject 101, and the subject 101 is made to visually recognize the test paper 301 for the time interval t5.
These steps (2) to (5) are one loop,
Hereinafter, the drive of the ultrasonic motor 108 and the change of the visual function control means 107 are changed in the order of step (2), step (3), step (4), step (5), step (2), ... step (5). The loop is repeated N times.

In this embodiment, a technique called block design used in general brain function measurement is used.
In the block design, a state in which the visual function of the subject 101 called a rest block is not controlled and a state in which the visual function of the subject 101 called a task block are controlled alternately.
In the present embodiment, the state in which the visual function is controlled is a state in which the polarizing plate 302 is fixed in front of the subject's 101 eye.
Then, two types of images are acquired: a brain function image obtained by the rest block and a brain function image obtained by the task block.
These are two types of images, namely, a brain function image in which the visual function is controlled and a brain function image in a state where the visual function is not controlled.
By comparing these two types of images, it is possible to obtain a brain function image that reflects the activity state of the brain in which the visual function is controlled.
In this embodiment, step (3) corresponds to a task block, and step (5) corresponds to a rest block.

Next, a brain function image acquisition sequence by the fMRI method will be described with reference to FIG.
First, the timing for controlling the visual function of the subject 101 is synchronized with the timing for starting imaging by the fMRI method.
Then, the brain function image when the test paper 301 is visually recognized through the polarizing plate 302 in the task block, that is, the time interval t3 in step (3), and the brain function image obtained in the rest block, that is, the time interval t5 in step (5). And get respectively.
In this embodiment, since the loop from step (2) to step (5) is repeated N times, N brain function images in the task block and N brain function images in the rest block are obtained.
The brain function when controlling the visual function of the subject by removing noise by performing image processing such as averaging these images and finally comparing the brain function images at the time of task block and rest block An image can be obtained.
Then, by analyzing the obtained brain function image, it is possible to measure changes in brain activity (activity such as the third visual cortex) related to the subject's stereoscopic vision.

In this embodiment, in step (2) and step (4), the ultrasonic motor 108 is rotated to change the visual function control means 107 installed in front of the eye of the subject 101.
Here, it is desirable to create a brain function image acquisition sequence of the fMRI method so as not to acquire a brain function image during the time interval between t2 and t4.
There are two reasons for this. One is the visual function control device 106 of the present embodiment, in which the visual function control means 107 to be presented to the subject 101 is changed by rotating the holding means 201.
Therefore, a certain amount of time is required to change the visual function control means 107.
Therefore, the task and rest visual function control may be mixed in this time interval.
Another reason is that a slight electromagnetic wave generated by driving the ultrasonic motor 108 may cause deterioration of the brain function image.
That is, by stopping the acquisition of the brain function image during the time interval in which the ultrasonic motor 108 is being driven, noise due to the driving of the ultrasonic motor 108 is superimposed on the image data used in the analysis after the measurement. It can be suppressed.
Note that, depending on the type of MRI apparatus, there is a case where acquisition of a brain function image only between t2 and t4 cannot be stopped as described above.
In this case, after acquiring the brain function image over the entire measurement period, the brain function image acquired in the time interval of t2 and t4 is not used, and only the image data acquired at t3 and t5 is analyzed, thereby obtaining the desired brain A functional image can be obtained.

[Example 3]
As a third embodiment, a configuration example using a linear drive type actuator instead of a rotary actuator using an ultrasonic motor as in the first embodiment as a driving unit used in the visual function control device 106 will be described with reference to FIG. .
As shown in FIG. 6, the linear drive type actuator of this embodiment has a plurality of visual function control units (602, 603, 604) set in a line on the holding unit 601, and is held by the linear drive type actuator 605. Connected to means 601. The linear drive actuator 605 moves the holding unit 601 in a linear direction illustrated by 606.
The visual function of the subject can be controlled by driving the linear drive actuator and changing the relative position between the visual function control means 602 to 604 and the subject 101.
In this case, as the actuator, it is preferable to use a linear drive type actuator using a piezoelectric element made of a non-magnetic material.

[Example 4]
As Example 4, a configuration example in which the visual function control device according to the present invention is applied to a magnetoencephalograph (MEG) will be described with reference to FIG.
When a magnetoencephalograph is used, changes in brain activity can be measured and imaged with good time accuracy. A magnetoencephalograph main body (not shown), a visual function control device, and a visual stimulus presentation device are installed in the magnetic shield room.
The subject 701 wears a helmet-like dewar-type sensor assembly 702 in which a magnetic sensor is housed on the head.
The visual function control device 703 made of a non-magnetic material is installed in front of the subject 701 so that the visual function of the subject 701 with respect to the visual stimulus presentation device 704 can be controlled. The visual stimulus presentation device 704 is also preferably composed of a non-magnetic screen, a real object, or the like.
The procedure of brain function measurement performed using this system can be the same as the procedure shown in the first to third embodiments.
By using the visual function control device of the present invention as in the present embodiment described above, the brain function measurement can be performed while reducing the noise applied to the magnetoencephalograph.
In addition, since the magnetoencephalograph has high time resolution, it is possible to measure the brain function of the subject at the timing when the visual function control means is changed.
Thereby, it becomes possible to measure the activity state of the brain in the process of controlling the visual function.

DESCRIPTION OF SYMBOLS 100: MRI apparatus 101: Test subject 102: MRI apparatus bed 103: Gradient magnetic field coil 104: Superconducting magnet 105: Cylindrical measuring part 106: Visual function control apparatus 107: Visual function control means 108: Ultrasonic motor 109: Projector 110 : Screen 111: Mirror 112: MR signal detection coil

Claims (7)

A visual function control device used to control the visual function of the subject when performing a device for measuring the brain function of the subject by presenting a visual stimulus to the subject and detecting a change in the magnetic field,
Visual function control means comprising a non-magnetic material for controlling the visual stimulus presented to the subject;
Drive control means for controlling the drive of the visual function control means;
A visual function control device comprising:   The said visual function control means is comprised by any one of a lens, an eye shield, a polarizing plate, a neutral density filter, a prism, a pinhole, or those combination, The Claim 1 characterized by the above-mentioned. Visual function control device.   The visual function control device according to claim 1, wherein the drive control unit includes an actuator made of a non-magnetic material.   A magnetic resonance imaging apparatus comprising the visual function control device according to claim 1.   A magnetoencephalograph comprising the visual function control device according to any one of claims 1 to 3. Using a visual function control device comprising a visual function control means made of a non-magnetic material for controlling a visual stimulus presented to a subject, and a drive control means for controlling the drive of the visual function control means, A brain function measuring method for measuring a subject's brain function by detecting a change,
A first step of providing a state in which the visual function of the subject is controlled by using the visual function control means and the drive control means;
Acquiring a brain function image in the first step, and analyzing the brain function image;
The brain function measuring method characterized by having.   7. The brain function measuring method according to claim 6, wherein the first step includes a step of periodically switching and providing a state in which the visual function of the subject is controlled to a plurality of states having different properties. .

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