JP2002272693A - Apparatus for analyzing eye fixation related potential - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause eye fixation related potential or a representative value extracted from it to be displayed in a way easy to view in a short cycle of renewal, for plural parts of the brain. SOLUTION: An eye-movement end point detecting part detects the end point of a saccade (rapid eye movement) on the basis of an eye-movement signal and supplies its signal to a primary storage part 4. Each time a saccade ends, the primary storage part 4 stores brain waves consecutively as unit brain waves within a certain period of time from the end point of the saccade, for plural parts of the brain. Each time a saccade ends, a computing part 5 computes, for each of the plural parts of the brain, the average of the unit brain waves stored in the primary storage part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an eyeball retention-related potential analyzer.

[0002]

2. Description of the Related Art An electroencephalogram is a weak electric potential fluctuation indicating a comprehensive activity of a large number of nerve cells (neurons) in the brain. When a human or an animal receives a stimulus from the outside, a corresponding potential change occurs in an electroencephalogram. Such an event-related potential (ERP) is buried in an electroencephalogram (β-wave) because of its small amplitude and cannot be normally detected. However, when the brain waves generated for a plurality of events are aligned at the time of occurrence of the event and then averaged, the spontaneous random components of the brain waves approach zero, and the S / N of the event-related potential is reduced. The ratio increases in proportion to the number of additions. Therefore, it becomes possible to detect an event-related potential.

[0003] By the way, when the eye movement when a person is looking at an object freely is recorded, rapid eye movement (saccade:
saccade) and a staircase pattern consisting of eyeball retention. The end point of the saccade is the start point of the eyeball holding. During the saccade, the visual signal from the retina to the brain is suppressed (saccade suppression), so that the movement of the background during exercise is not perceived. Therefore, humans can input visual information while the eyeball is stationary.

A potential related to eye movement as one type of event-related potential (eye fixation-related potential: EFRP (eye fixati
on related potential)) is the so-called lambda reaction (la
mbdaresponse) is known to occur at the end of the saccade. Therefore, a device that can detect a lambda reaction accompanying eye movement using this knowledge has been proposed in Japanese Patent Application Laid-Open No. 55-101244 by the present inventor. The lambda reaction detection device described in this publication includes an eye movement end timing detection device that inputs an eye movement signal and generates a pulse corresponding to the end of eye movement, and a unit electroencephalogram that converts an electroencephalogram within a predetermined time based on the pulse. A primary storage device that stores as a, a logic determiner that sends a signal for erasing unit brain waves to the primary storage device when there is a factor that disturbs the brain wave within the fixed time, and when there is no such factor A secondary storage device for adding and integrating and storing unit brain waves from the primary storage device to be sent, and a display for displaying a lambda response obtained by the averaging in the secondary storage device.

[0005]

However, the apparatus described in the above publication has a relatively long update cycle of the displayed lambda response, and furthermore, the lambda response waveform as the eye-holding-related potential is displayed in one region of the brain. However, there is a problem that the convenience is poor. Therefore, the representative value of the eyeball retention-related potential extracted from the waveform of the lambda reaction or extracted therefrom, for multiple parts of the brain,
There is a need for a device that can display easily in a short update cycle.

Accordingly, an object of the present invention is to provide an eye-holding-related potential analyzer capable of displaying the eye-holding-related potential or a representative value extracted therefrom in a plurality of parts of the brain in a short refresh cycle in an easily viewable manner. To provide.

[0007]

According to another aspect of the present invention, there is provided an eye-holding-related potential analyzer for detecting an eye movement end point based on an eye movement signal. And a primary storage for sequentially storing, for each of a plurality of parts of the brain, a brain wave within a certain period from the eye movement end time as a unit brain wave every time the eye movement end time detection means detects the eye movement end time point. Means, and each time a new unit brain wave is stored in said primary storage means,
Adding means for selecting a predetermined number of continuous unit brain waves including the latest unit brain waves stored from the plurality of unit brain waves stored in the primary storage unit and adding the unit brain waves,
An addition exclusion signal generation unit for generating a signal for excluding a unit brain wave treated as noise from an object to be added by the addition unit; and a second unit for storing the signal added by the addition unit for each of the parts. Secondary storage means, extraction means for extracting a representative value of a signal stored in the secondary storage means for each of the parts, and a signal stored in the secondary storage means or a representative extracted by the extraction means. Display means for displaying the value as a map in association with the part.

According to the first aspect, by adding the unit brain waves within a certain period from the end of the eye movement, a random component in the brain waves can be eliminated, and the eye-holding-related potential can be detected.

In addition, since unit brain waves treated as noise can be excluded from addition targets, it is possible to detect the eyeball retention-related potential with high accuracy.

The operation of the primary storage means, the addition means, the secondary storage means, and the extraction means is performed for each of a plurality of parts of the brain, and the signal stored in the secondary storage means or the extracted representative value is used as the part. Since the map is displayed in association with the map, it is possible to grasp at a glance the distribution state of the eyeball retention-related potential or its representative value for each part of the brain.

In addition, since the representative value extracted from the eye-holding-related potential can be displayed as a map instead of the eye-holding-related potential as it is, the representative value (for example, the amplitude, wavelength, phase difference, The use of such a type of latency makes it possible to display a map that is easy to see.

Each time a new unit electroencephalogram is stored in the primary storage means, a predetermined number of continuous unit electroencephalograms including the most recently stored unit electroencephalogram are selected from a plurality of unit electroencephalograms stored in the primary storage means. Therefore, the map can be displayed in a shorter update cycle than when the addition is performed each time a predetermined number of unit brain waves are stored.

Since the eye-holding-related potential varies depending on the level of sensation or attention of humans or animals, the map of the eye-holding-related potential or its representative value obtained as described above is used for safety measures when driving a car. It is extremely effective in detecting human attention in the fields of design evaluation, lighting evaluation, and the like, or as a medical device.

According to the first aspect of the present invention, when the eye movement end time detecting means detects the eye movement end time point in a state where the upper limit number of unit electroencephalograms are already stored for each part of the brain, Each time the detection is performed, the oldest stored unit brain wave is erased from the primary storage unit, and a new unit brain wave is written into the primary storage unit. Further, the adding means may not only add a predetermined number of unit brain waves, but also obtain an average of the unit brain waves by dividing the unit brain waves by a predetermined number. An operation that can increase the S / N ratio may be performed. The addition exclusion signal output means may be a signal for erasing a unit brain wave treated as noise from the unit brain wave stored in the primary storage means, or simply adding a unit brain wave treated as noise without erasing. May be a signal instructing removal from the signal. Further, it is preferable that the extraction means performs an interpolation process between the representative values extracted for each of the plurality of parts so that the display means can display a map having substantially continuous representative values. The map displayed on the display means may be two-dimensional or three-dimensional.

According to a second aspect of the present invention, there is provided an eyeball retention-related potential analyzer.
A movement direction detection means for detecting a movement direction of the eyeball based on the eyeball movement signal, and a movement of the eyeball based on the movement direction of the eyeball detected by the movement direction detection means; A change time point detecting means for detecting a time point when the direction changes, and based on the detection by the change time point detecting means, determines whether or not the movement direction of the eyeball has changed continuously after being the same within a predetermined time range. And determining means for determining.

Generally, EOG (electro-oculograph)
The measurement data of the eye movement obtained by the method or the corneal reflex method includes a small amount of high-frequency noise that is not related to the actual eye movement. Therefore, the eye-holding-related potential analyzer according to claim 2 detects the end point of the eye movement using the high frequency noise. It can be considered that the direction of the eye movement changes in a short cycle except during the saccade, that is, when the eye is stationary. Further, the saccade does not last for a long time beyond the predetermined time. Therefore, a case where the direction of movement of the eyeball is continuously the same within the predetermined time range (usually 30 ms to 70 ms) can be regarded as a saccade, while the direction of movement of the eyeball exceeds the predetermined time range. If the values are continuously the same, it can be regarded as noise accompanying the measurement. Therefore, according to the second aspect configured as described above, it is possible to reliably and easily detect the end of the saccade based on the eye movement signal.

According to a third aspect of the present invention, there is provided an eyeball retention-related potential analyzer,
The movement direction detecting means detects the direction of movement of the eyeball in accordance with the sign of the difference between the signal values of the eye movement signal at two adjacent times, and the change time point detection means is detected by the movement direction detection means. 2 of the signal indicating the direction of movement of the eyeball
It is characterized by detecting a point in time when the direction of movement of the eyeball changes according to the sign of the product of the signal values at the point in time.

According to claim 3, by a simple operation,
It is possible to quickly detect the direction of movement of the eyeball and the time when it changes.

According to a fourth aspect of the present invention, there is provided an eyeball retention-related potential analyzer.
The display means is capable of displaying a plurality of the maps as still images on a screen over time.

According to the fourth aspect, the observer can easily recognize the change of the map over time while comparing the map at a plurality of times directly.

According to a fifth aspect of the present invention, there is provided an eye-holding-related potential analyzer.
The display means is capable of displaying the map as a moving image on a screen.

According to the fifth aspect, the observer can easily recognize the dynamic change while paying attention to one map. Also, since one map can be displayed relatively large, it is possible for the observer to easily grasp the waveform and the representative value on the map.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an eyeball retention-related potential analyzer according to the present embodiment. The eye-holding-related potential analyzer 1 shown in FIG. 1 may be constituted by a general-purpose personal computer system, and includes an eye movement end point detecting unit 3, a primary storage unit 4, a calculation unit 5, and a secondary storage. A section 6, a display control section 7, a display 8, and an erasure signal generation section 9 are included. Further, the eye movement end point detection unit 3 includes a movement direction detection unit 3a for detecting the movement direction of the eye ball, a change time point detection unit 3b for detecting a time point when the movement direction of the eye ball changes, and a movement direction of the eye ball. A determination unit 3c for determining whether or not it has changed after being the same continuously within a predetermined time range.

Based on the EOG method, the movement direction detector 3a outputs a horizontal eye movement signal representing the horizontal movement of the eye output from two electrodes attached to the left and right temples of a human, and an eye movement, respectively. Vertical eye movement signals representing the vertical movement of the eye, which are output from the two electrodes attached to the upper and lower electrodes, respectively, are supplied via amplifiers (not shown). An increase in the signal value of the horizontal eye movement signal or the vertical eye movement signal based on the EOG method indicates that the eyeball has moved horizontally or vertically in a direction approaching the + electrode, and a decrease in the signal value indicates that the eyeball approaches the-electrode. Indicates horizontal or vertical movement in the direction. From this characteristic, the direction of eye movement at time n is determined by the signal value S (n) at time n.
, And the signal value S (n + 1) at time n + 1, which is the next sampling timing adjacent thereto, is obtained from the polarity of the difference. In other words, if the value of O (n) expressed by the following equation (1) is +1, the eyeball moves horizontally or up and down in the + electrode direction, and if −1, the eyeball moves horizontally in the −electrode direction. It means that it is moving or moving up and down. Therefore, in the present embodiment, the movement direction detection unit 3a obtains the value of O (n) based on Equation (1) for each of the horizontal eye movement signal and the vertical eye movement signal, and sequentially outputs the values. Note that a vector signal obtained by combining the horizontal eye movement signal and the vertical eye movement signal may be used as the signal S (n). Also, when the eye movement is detected by another method such as the corneal reflection method, the direction of movement of the eye may be obtained by performing the same calculation. O (n) = (S (n + 1) -S (n)) / √ ((S (n + 1) -S (n)) ² ) (1)

The value of O (n) obtained based on equation (1) for each of the horizontal eye movement signal and the vertical eye movement signal is supplied from the movement direction detection section 3a to the change point detection section 3b. . The change point detection unit 3b calculates the following equation (2) for each of the horizontal and vertical directions.
, The eye movement direction signal O (n) at time n
Is multiplied by the eye movement direction signal O (n-1) at time n-1 which is the immediately preceding sampling timing, and the resulting change time point indication signal C
(N) is sequentially obtained. If the value of the change time point instruction signal C (n) is 1, no change occurs in the movement direction of the eyeball at the two adjacent sampling timings, and if −1, the movement direction of the eyeball at the two close sampling timings. Is inverted, the change time point detection unit 3b according to the present embodiment sets the value of the change time point instruction signal C (n) to -1 for each of the horizontal eye movement signal and the vertical eye movement signal. The signal indicating the time is sequentially output as a signal indicating the time when the direction of movement of the eyeball changes. C (n) = O (n) * O (n-1) (2)

A signal indicating a point in time when the direction of movement of the eyeball changes for each of the horizontal eyeball movement signal and the vertical eyeball movement signal is supplied from the change point in time detection section 3b to the judgment section 3c. Based on this signal, the determination unit 3c determines whether the direction of movement of the eyeball has been continuously the same within a predetermined time range and then changed. Because, as described above, the direction of movement of the eyeball is within a predetermined time range (usually 30 m
(Seconds to 70 ms) A case where the same is continuously the same can be regarded as a saccade, while a case where the direction of movement of the eyeball is continuously the same over a predetermined time range is considered to be noise accompanying the measurement. Because it is reasonable to regard it. In the determination by the determination unit 3c, the signals indicating the time points at which the movement directions of the eyeball obtained for each of the horizontal eyeball movement and the vertical eyeball movement change are treated as indistinguishable. In other words, even if the value of the change time instruction signal C (n) becomes -1 only in the horizontal direction at a certain time and the value of the change time instruction signal C (n) becomes -1 only in the vertical direction next, A determination is made whether the interval between the two time points is within a predetermined time range.

In the present embodiment, the determination unit 3c determines whether the saccade detected as described above has a shorter moving distance (small amplitude) than a predetermined distance, and determines whether the saccade ends. Within a certain period of time (300 ms
It is also determined whether or not an eyeball movement with a large moving distance (about 10% or more of the immediately preceding eyeball movement) has occurred. Then, in the case of these, the saccade is not treated as a saccade. The result of the judgment by the judgment unit 3c is supplied to the primary storage unit 4 and the erasure signal generation unit 9 as a trigger signal (saccade end time detection signal) indicating the end time of the saccade.

In the eye-holding-related potential analyzer 1 of this embodiment, since the eye-movement end point detecting unit 3 is configured as described above, the movement direction of the eyeball and the point at which it changes can be simply determined. It is possible to quickly detect the end of the saccade based on the eye movement signal and to detect the end of the saccade reliably and easily.

The erasure signal generation unit 9 receives the horizontal saccade motion signal and the vertical saccade motion signal together with the saccade end time detection signal from the judgment unit 3c and an amplifier (not shown).
Is supplied via The erasure signal generation unit 9 determines whether or not the differential output level is equal to or more than a certain value from the vertical eye movement signal. If the differential output level is equal to or more than the certain value, noise accompanying eyelid movement (blinking) is generated in the brain wave. As a result, a signal (erasing signal) for erasing the brain wave (unit brain wave described later) stored in the primary storage unit 4 at this time is output. The erasure signal generation unit 9 includes an erasure signal due to such eyelid movement, and it is possible that noise is generated in brain waves by detecting an eye movement artifact based on the horizontal eye movement signal and the vertical eye movement signal. It is checked whether or not there is, and an erasure signal for erasing unit brain waves to be treated as noise from the primary storage unit 4 is sequentially output.

The primary storage unit 4 stores, together with the saccade end detection signal from the determination unit 3c and the erasure signal from the erasure signal generation unit 9, 10 to 256 pairs of affixed to the scalp corresponding to the part of the brain. An electroencephalogram signal is supplied from the electrode (see FIG. 4). Each time the saccade ends, the primary storage unit 4 sequentially stores the brain waves in a certain period starting from the end of the saccade as unit brain waves as a file for each part of the brain in a ring shape. That is, when the end of the saccade is detected by the eye movement end time point detection unit 3 in a state where the upper limit number of unit brain waves are already stored in the primary storage unit 4 for each part of the brain, every time the detection is performed, The oldest stored unit brain waves are erased from the primary storage unit 4 for all parts of the brain, and new unit brain waves are written to the primary storage unit 4 for each part of the brain.

The unit brain waves targeted for erasure by the erasure signal are temporarily stored in the primary storage unit 4 and then erased before being supplied to the calculation unit 5. At this time, a plurality of unit brain waves corresponding to a plurality of parts of the brain stored in the primary storage unit 4 are collectively erased at the same timing.

The arithmetic unit 5 sequentially performs an arithmetic operation for obtaining the average of the unit brain waves stored in the primary storage unit 4 for each part of the brain every time the saccade ends in principle. That is, the arithmetic unit 5 selects a predetermined number of continuous unit brain waves including the latest unit brain wave stored from the plurality of unit brain waves stored in the primary storage unit 4 and adds the unit brain waves for each part of the brain. The result is divided by the number of unit electroencephalograms to be added for one part of the brain.

The secondary storage unit 6 sequentially stores, for each part of the brain, an averaged waveform of unit brain waves, which is the result of the operation by the operation unit 5.

The display control unit 7 sequentially extracts representative values from the averaged waveform stored in the secondary storage unit 6 for each part of the brain. The representative value includes, for example, the amplitude, wavelength, phase difference, or latency as one type of the averaged waveform. Further, the display control unit 7 displays the averaged waveform stored in the secondary storage unit 6 or the representative value extracted for each part of the brain on the display 8 as a two-dimensional map according to the shape of the head. Are sequentially performed. The display control unit 7 obtains a representative value at a number of positions between the parts by interpolation from the representative values obtained for each part of the brain,
Control for displaying the map on the display 8 by color-coding the map based on the obtained multiple representative values may be performed.
As will be described later, a map displayed on the display 8 may be a plurality of maps each of which is displayed as a still image or a plurality of maps which are displayed as a moving image over time. Is 1 on display 8
Only one may be displayed.

Next, the operation of the eye-holding-related potential analyzer 1 according to the present embodiment configured as described above will be described.
This will be further described with reference to FIGS. FIG. 2 is a diagram for explaining a procedure of adding unit electroencephalograms in the eyeball retention-related potential analyzer according to the present embodiment. FIG.
FIG. 4 is a schematic diagram for explaining storage contents of a primary storage unit shown in FIG. FIG. 4 is a diagram illustrating an averaged waveform of the unit brain wave for each part of the brain. FIG. 5 is a diagram illustrating an example of a screen displayed on the display illustrated in FIG. FIG.
FIG. 14 is a diagram illustrating another example of a screen displayed on the display shown in FIG.

In order to use the eye-holding-related potential analyzer 1 according to the present embodiment, in order to extract the horizontal and vertical eye movement signals of humans and animals based on the EOG method,
As described above, two electrodes in each direction are pasted around the eyeball in advance. Further, in order to extract an electroencephalogram signal, 10 to 256 pairs of electrodes are attached to the scalp corresponding to the parts of the brain. The electrodes affixed to the scalp may be, for example, as shown in FIG. 4, 21 pairs corresponding to brain parts.
The horizontal and vertical eye movement signals are continuously supplied to the eye movement end point detection unit 3 and the erasure signal generation unit 9, and the electroencephalogram signal is continuously supplied to the primary storage unit 4.

As shown in FIG. 2A, an eye movement signal (here, both horizontal and vertical components are synthesized) is a saccade (a curve representing a signal) in which the eye is displaced with time. (A region in which the eyeball is tilted) and an eyeball in which the eyeball hardly changes are randomly repeated. Further, as shown in FIG. 2B, the electroencephalogram signal is a random signal seemingly unrelated to the eye movement.

After the analysis is started, when the end of the saccade is first detected by the judging section 3c of the eye movement end time detecting section 3 (time t1), the primary storage receiving the saccade end time detection signal from the judging section 3c. The part 4 starts from the time T
An electroencephalogram contained until the elapse of (set to a time shorter than the time until the next saccade starts) is stored as a unit electroencephalogram for each part of the brain to which the electrode is attached. For example, the parts of the brain corresponding to the places where the electrodes are attached are A,
FIG. 3 shows an example of the storage contents of the primary storage unit 4 in the case where four unit brain waves can be stored for each part, as represented by B. As shown in FIG. 3A, when the time T has elapsed from the time t1, unit brain waves ("bw1A", "bw1B") from the time t1 are stored for each of the parts A, B... Of the brain.

Next, when the end of the saccade is detected by the judging section 3c of the eye movement end time detecting section 3 (time t2), the primary storage section 4 which has received the saccade end time detection signal from the judging section 3c. Stores the brain waves included until the time T elapses from that point as unit brain waves for each part of the brain. In this way, when the time T has elapsed from the time (time t4) when the end of the fourth saccade is detected after the start of the analysis, as shown in FIG.
, Four unit brain waves ("bw1A", "bw2A", "bw3A", "bw4"
A ";" bw1B "," bw2B "," bw3B "," bw4
B ") will be stored.

The arithmetic unit 5 also outputs a fourth unit brain wave (""
bw4A "," bw4B ") are stored in the primary storage unit 4, and then an averaged waveform (EFRP-1) of the stored four unit brain waves is obtained for each of the parts A, B,. In the example, the average waveform of the four unit brain waves included in the time L1 from the end time t1 of the first saccade to the end time t5 of the fifth saccade (at the same time when the start points of the unit brain waves are aligned) The waveform obtained by dividing the added amplitude at each time by the number of unit brain waves to be added at each time) is obtained. This is shown in FIG.
Letters such as “z” and “T8” are shorthand names of brain parts.As shown in FIG. 4, the averaged waveform of the four unit brain waves is one in which random components of the brain waves are excluded. Thus, the lambda reaction is expressed relatively clearly.
Is stored in the secondary storage unit 6 for each part of the brain.

Next, when the end of the saccade is detected by the judgment unit 3c of the eye movement end time detection unit 3 (time t5), the primary storage unit 4 which has received the saccade end time detection signal from the judgment unit 3c. As shown in FIG. 3 (c), the unit brain wave (“bw1A”, “bw1B”) stored first is deleted, and a new unit brain wave (“bw5A”, “bw5A”, "Bw5B") is stored. Then, the arithmetic unit 5 outputs the four unit electroencephalograms (“bw5A”, “bw2A”, “bw”) stored in the primary storage unit 4 included in the time L2.
"bw3A", "bw4A";"bw5B","bw2B","b
w3B "," bw4B ") is calculated for each part of the brain for each part of the brain.The averaged waveform obtained by the arithmetic part 5 is stored in the secondary storage part 6 for each part of the brain. In the same manner, in the eye-holding-related potential analyzer 1 of the present embodiment, the end of saccade is newly detected and a new unit brain wave is stored in the primary storage unit 4 in the same manner.
The averaged waveforms (EFRP-3, EFRP-4, EFRP-5) of the four unit brain waves included in the times L3, L4, L5... Are sequentially obtained, and are sequentially stored in the secondary storage unit 6. in this way,
According to the eye-holding-related potential analyzer 1 of the present embodiment,
By taking a so-called sliding average (moving average) every time a new unit brain wave is stored in the primary storage unit 4, there is an advantage that an averaging waveform can be obtained in a short cycle.

It should be noted that the primary storage section 4 stores the erase signal generation section 9
When the elimination signal is received from, the unit EEG related to the elimination signal is erased. At this time, a plurality of unit brain waves corresponding to a plurality of parts of the brain stored in the primary storage unit 4 are collectively erased at the same timing. For example, time T from time t5
When the unit brain waves (“bw5A”, “bw5B”) within are erased as noise due to artifacts such as eyelid movements, the primary storage unit 4 that has received the erase signal outputs The unit brain waves (“bw5A”, “bw5”) once stored in the primary storage unit 4 as shown in FIG.
B ") are erased collectively for each part of the brain. Then, after a lapse of time T from the time when the end of the saccade is detected (time t6), as shown in FIG. The unit brain wave (“bw6A”, “bw6B”) is stored at the address where the “bw5A”, “bw5B”) was stored. ("Bw6A", "bw2A", "bw3
A "," bw4A ";" bw6B "," bw2B "," bw3
B ”,“ bw4B ”) is calculated for each part of the brain In this manner, the eyeball retention-related potential analyzer 1 of the present embodiment calculates only the unit brain waves without noise by the calculation unit 5.
, The eyeball-holding-related potential can be detected with high accuracy.

Each time the end of the saccade is detected, the display control section 7 determines the maximum amplitude and wavelength as a representative value from the averaged waveform of the unit brain waves stored in the secondary storage section 6 as described above. , And at least one of a phase difference and a latency as a kind thereof is sequentially extracted for each part of the brain, and a representative value at a number of positions where no electrodes are arranged is interpolated from the extracted representative value. Obtained sequentially by calculation. In addition, the display control unit 7 displays a map having a shape corresponding to the planar shape of the head on the display 8 based on the large number of representative values obtained in this manner according to the value of the representative value. Control for Then, by displaying the obtained map data on the display 8, it becomes possible for the operator to observe the temporal change in the distribution state of the representative value of the averaging waveform which is the eyeball retention-related potential. The display control unit 7 may perform control to display the shape of the averaged waveform itself on the display 8 as a map as shown in FIG. 4 instead of the representative value of the averaged waveform.

In the present embodiment, the display control unit 7
As shown in FIG. 5, control may be performed such that a plurality of color-coded maps, each of which is displayed as a still image, are displayed on the display 8 over time, or FIG. As shown, control may be performed such that one map displayed as a moving image is displayed on the display 8. In the former case, there is an advantage that the observer can easily recognize changes in the map over time while directly comparing the maps at a plurality of times, and in the latter case, the observer pays attention to one map. The advantage is that the dynamic change can be easily recognized while one map can be displayed relatively large, so that the observer can easily grasp the waveform and the representative value on the map. There is. By using the eye-holding-related potential displayed on the display 8 in this manner, it is possible to detect the sense or attention level of a human or animal in a daily environment without applying an extra psychological load.

As described above, according to the eye-holding-related potential analyzer 1 of the present embodiment, the unit brain wave within a certain period from the end of the saccade is added for each brain part, so that the random number in the brain wave is added. By eliminating the components, the eyeball retention-related potential can be detected in multiple channels almost in real time (3 to 4 times / sec). This allows
Since it becomes possible to observe the change in the mutual activity of each part of the brain, it is possible to easily compare the parts of the brain.
In addition, since unit brain waves treated as noise can be excluded from addition targets, the eyeball retention-related potential can be detected with high accuracy.

The operation of the primary storage unit 4, the operation unit 5, and the secondary storage unit 6 and the operation of extracting the representative value by the display control unit 7 are performed for each of a plurality of parts of the brain. Since the stored signal or the extracted representative value is displayed as a map in association with the region, it is possible to grasp at a glance the eyeball retention-related potential or the distribution state of the representative value for each region of the brain. . In addition, since the representative value extracted from the eyeball-holding-related potential, instead of the potential, can be displayed as a map, it is possible to display a map that is easy to read using a representative value suitable for the application.
Further, each time a new unit brain wave is stored in the primary storage unit 4, a plurality of unit brain waves are stored in the primary storage unit 4 in a ring shape and are added, so that a predetermined number of unit brain waves are stored. It is possible to display the map in a shorter update cycle than when the addition is performed every time.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made within the scope of the appended claims. Things. For example, in the above-described embodiment, the calculation unit performs the averaging of the unit brain waves, but the calculation performed by the calculation unit is the S / N of the eyeball retention-related potential.
The average does not have to be the average if the unit brain waves are added under the condition of improving the ratio. Further, the number of additions of the averaging performed by the arithmetic unit is 4 in the above-described embodiment, but this number is merely an example and may be changed as appropriate, such as setting the number of additions to 50. Further, the method of extracting the eye movement signal is not limited to the EOG method, but may be another method.
Further, in the above-described embodiment, the eye movement end time detection unit has the movement direction detection unit, the change time detection unit, and the determination unit, but the eye movement end time detection unit does not have these. The end point of the saccade may be detected by another method.

Further, in the above embodiment, the storage upper limit number of the unit brain wave stored in the primary storage unit is the same as the addition number in the averaging operation, but the storage upper limit number is the addition number in the averaging operation. May be exceeded. In that case, it is necessary to select and add a predetermined number of unit brain waves stored at consecutive timings including the latest unit brain wave. Further, in the above-described embodiment, a two-dimensional map is displayed on the display, but a three-dimensional map associated with the shape of the head may be displayed on the display. Further, in the above-described embodiment, a color map that is color-coded is displayed on the display. However, a map that three-dimensionally represents a change in a representative value such as a latency as a change in a mountain height is displayed on the display. The map may be displayed, or a map that is color-coded and three-dimensionally represents a change in the representative value as a change in the mountain height may be displayed on the display.

[0050]

As described above, according to the first aspect, the eyeball retention-related potential is detected by adding unit brainwaves within a certain period from the end of eyeball movement to eliminate random components in brainwaves. Will be able to do it. In addition, since unit brain waves treated as noise can be excluded from addition targets, the eyeball retention-related potential can be detected with high accuracy. Also, the operations of the primary storage means, the addition means, the secondary storage means and the extraction means are performed for each of a plurality of parts of the brain, and the signals stored in the secondary storage means or the extracted representative values are associated with the parts. Since it is displayed as a map, it is possible to grasp at a glance the distribution state of the eyeball retention-related potential or its representative value for each part of the brain. In addition, since a representative value extracted from the eyeball-holding-related potential, instead of the potential, can be displayed as a map, a map that is easy to read can be displayed by using a representative value suitable for the application. Each time a new unit brain wave is stored in the primary storage unit, a predetermined number of continuous unit brain waves including the latest unit brain wave stored from the plurality of unit brain waves stored in the primary storage unit are selected and added. Therefore, it is possible to display the map in a shorter update cycle than when addition is performed every time a predetermined number of unit brain waves are stored. Eye-holding-related potentials fluctuate depending on the level of sensation and attention of humans or animals, so the map of eye-holding-related potentials or their representative values obtained as described above is used to evaluate safety measures during driving and evaluation of design. It is extremely effective for detecting human attention in fields such as evaluation of lighting and for use as a medical device.

According to the second aspect, the end of the saccade can be reliably and easily detected based on the eye movement signal. According to the third aspect, it is possible to quickly detect the direction of movement of the eyeball and the point in time when the direction changes by a simple calculation.

According to the fourth aspect, the observer can easily recognize the change of the map with the passage of time while directly comparing the map at a plurality of times. According to the fifth aspect, the observer can easily recognize the dynamic change while paying attention to one map. Also, since one map can be displayed relatively large, it is possible for the observer to easily grasp the waveform and the representative value on the map.

[Brief description of the drawings]

FIG. 1 is a block diagram of an eyeball retention-related potential analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a procedure of adding unit electroencephalograms in the eyeball retention-related potential analysis device according to one embodiment of the present invention.

FIG. 3 is a schematic diagram for explaining contents stored in a primary storage unit shown in FIG. 1;

FIG. 4 is a diagram illustrating an averaged waveform of unit brain waves for each part of the brain.

FIG. 5 is a diagram illustrating an example of a screen displayed on the display shown in FIG.

6 is a diagram illustrating another example of a screen displayed on the display illustrated in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Eye-holding-related electric potential analyzer 3 Eye movement end point detection unit (eye movement end point detection unit) 3a Movement direction detection unit (movement direction detection unit) 3b Change point detection unit (change point detection unit) 3c Judgment unit (judgment unit) 4) Primary storage unit (primary storage unit) 5 Operation unit (addition unit) 6 Secondary storage unit (secondary storage unit) 7 Display control unit (extraction unit) 8 Display (display unit) 9 Erasure signal generation unit (addition exclusion) Signal generation means)

Claims (5)

[Claims] 1. An eye movement end time detecting means for detecting an eye movement end time point based on an eye movement signal, and each time the eye movement end time point is detected by the eye movement end time detecting means, an eye movement end time is detected. A primary storage unit for sequentially storing brain waves within a certain period from a time point as a unit brain wave for each of a plurality of parts of the brain, and each time a new unit brain wave is stored in the primary storage unit, the primary storage unit Adding means for selecting a predetermined number of continuous unit electroencephalograms including the latest stored unit electroencephalogram from a plurality of stored unit electroencephalograms and adding them for each of the parts; and adding the unit electroencephalogram treated as noise. An addition exclusion signal generation unit for generating a signal for exclusion from the addition target in the above; a secondary storage unit for storing the signal added by the addition unit for each of the parts; Extracting means for extracting a representative value of the signal stored in the secondary storage means for each of the parts; associating the signal stored in the secondary storage means or the representative value extracted by the extracting means with the part; An eyeball retention-related potential analyzing device, comprising: a display unit for displaying the potential as a map. 2. An eye movement end point detecting means, a movement direction detecting means for detecting an eye movement direction based on the eye movement signal, and an eye movement direction detected by the movement direction detection means. Change time point detecting means for detecting the time point at which the movement direction of the eyeball changes based on, based on the detection by the change time point detection means, after the movement direction of the eyeball is continuously the same within a predetermined time range The eyeball retention-related potential analyzer according to claim 1, further comprising a determination unit configured to determine whether or not the potential has changed. 3. The movement direction detecting means detects the direction of movement of the eyeball in accordance with the sign of the difference between the signal values of the eye movement signal at two time points close to each other. 3. The method according to claim 2, further comprising detecting a time point at which the movement direction of the eyeball changes in accordance with a sign of a product of signal values at two adjacent time points of the signal representing the movement direction of the eyeball detected by the detection means. Eye-holding-related potential analyzer. 4. The eyeball according to claim 1, wherein the display unit is capable of displaying a plurality of the maps as still images on a screen as time passes. Stationary potential analyzer. 5. The eyeball retention-related potential analyzer according to claim 1, wherein the display unit is capable of displaying the map as a moving image on a screen.