JPH0779809B2 - Evoked potential measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an evoked potential measuring device, and is capable of simultaneously measuring not only an evoked potential but also a subjective amount representing a subject's judgment regarding the content of sensory stimulation. Regarding

[Conventional technology]

When a human sensory organ is stimulated, for example, by showing strobe light or listening to a sound, the stimulus is transmitted from the sensory organ to the cerebral cortex, and an electric potential is evoked in the part of the brain involved in information processing of the stimulus. . The evoked potential in the brain is called the evoked potential and is measured by electrodes placed on the scalp. Evoked potentials for sensory stimuli are frequently used in basic experiments in physiology, psychology, and ergonomics.

In recent years, with the development of information processing technology, work using advanced information processing devices has been increasing in offices and homes. VDT fatigue has become a problem as the number of advanced and detailed visual tasks using VDT (Video Display Terminal) has increased. As a method for quantitatively measuring this VDT fatigue, for example, by visually presenting a stimulus and examining the evoked visual evoked potential, it is possible to perform an objective measurement of fatigue, and to solve the problem of VDT fatigue. It is effective in resolving. On the other hand, considering that the problem of VDT fatigue is caused by the subjective complaints of VDT users, it is represented not only by the objective amount such as physiological index represented by visual evoked potential but also by the subjective symptom test. It is a powerful method to clarify VDT fatigue by measuring the subjective amount and clarifying the relationship between them.

The following method is a general method for obtaining an evoked potential. For example, in the case of a visual evoked potential, a light emitting body such as a strobe is used as a stimulus, and the potential from the moment of light emission is measured for a certain period of time. The electrical potential evoked by the scalp on the information processing site of the brain corresponding to the visual sense by one luminescence stimulation is about a dozen or so.
Dozens of microvolts. This potential is lower than the potential due to activity from sites other than the site related to visual information processing in the brain, and the potential obtained by one measurement also includes the potential affected by these. . So, multiple times,
The same measurement is repeated, and the potential at the same time after light emission is added at each time to obtain an average value. By considering the influence of the electric potential from other parts of the brain included in each measured electric potential as random noise, these noises can be brought close to zero by adding each electric potential. Analysis is performed using the evoked potentials obtained by addition and averaging.

As a conventional evoked potential measuring device, for example, Technical Report of Television Society of Japan, February 1987, Volume 10, No. 48, 1 to 6
Nakamura and Morita on the page "VEP spectral sensitivity characteristics" (V
EP is an abbreviation for Visual Evoked Potentials, Visual Evoked Potentials, and visual evoked potentials). It has a basic configuration as shown in Figure 5,
The stimulus is presented from the visual stimulus presenting section 51 in synchronization with the signal output from the pulse generator 54. The potential induced by the stimulus is input to the amplifier 52 via the electrode 57. The waveform of the signal amplified by the amplifier 52 is displayed on the monitor 53 for the observer to observe, and the amplified signal is synchronized with the signal output from the pulse generator 54 and pasted by the adder 55. Is added in an analog manner to the signal of. The added result is recorded on the recording paper as a graph in the XY recorder 56.

[Problems to be Solved by the Invention]

However, since the data recorded on the recording paper is not a numerical value but a graph, a reading error or the like may be mixed when reading numerical values such as the latency and the amplitude of the evoked potential. Furthermore, the work of reading from the graph has been a burden on the measurer. In addition, it takes time to measure the evoked potential because the data is not read from the graph or automatically measured according to the measurement procedure. For example, when performing fatigue measurement using an evoked potential, it is necessary to quickly measure the evoked potential as a physiological index, which may reduce reliability as an index of fatigue. In addition, if it is attempted to carry out a VDT fatigue subjective symptom test continuously, the measurement time will be further extended, which may increase the burden on the subject.

[Problems to be Solved by the Invention]

It is possible to measure only evoked potentials with the conventional evoked potential measurement device described above, and for example, if the subjective symptom test is continuously performed to measure VDT fatigue, the measurement time is extended and the burden on the subject is considered to be large. It was

An object of the present invention is to enable simultaneous measurement of a subjective amount related to a subject's judgment regarding the contents of an evoked potential and a sensory stimulus, and eliminate an increase in measurement time caused by continuously measuring an evoked potential and a subjective amount. It is to reduce the burden on the subject and to prevent the influence of the measurement time from being mixed into the evoked potential. Further, it is to improve the reliability of the obtained data and reduce the burden on the measurer by allowing the measurer to flexibly set the measurement procedure and automating the measurement.

[Means for Solving the Problems]

The evoked potential measuring device of the present invention is a character string presenting means for presenting a character string representing some test item as a sensory stimulus to be given to a subject, and a character string data recording means for storing data relating to the content of the character string presented to the subject. A character string presentation control means for controlling the content of the character string to be presented and the presentation time,
Subjective amount input means for inputting a subjective judgment regarding the content of the presented character string, subjective amount data collecting means for collecting the data output by the subjective amount input means, and output by the subjective amount data collecting means. Subjectivity data analysis means for analyzing the subjective quantity data and the subjective quantity that quantitatively represents the judgment regarding the content of the character string output from the character string presentation control means, and the brain potential evoked by the presented character string. Evoked potential measuring means for measuring and amplifying, evoked potential recording control means for controlling storage of brain potential signals output from the evoked potential measuring means, and recording cerebral potential signals output from the evoked potential recording control means The evoked potential recording means and the evoked potential recording means output the brain potential signal to obtain an addition and an average value of the brain potential, and a characteristic parameter including latency and amplitude of the evoked potential. Evoked potential analysis means for extracting, evoked potential measurement procedure control means for controlling the character string presentation control means, the evoked potential recording control means, and the evoked potential analysis means according to the procedure for measuring the evoked potential, and the evoked potential An objective quantity / subjective quantity relation analyzing means for analyzing the relationship between the evoked potential and the subjective quantity from the characteristic parameter of the evoked potential output from the analyzing means and the subjective quantity related to the content of the character string output from the subjective quantity data analyzing means. Have

[Action]

The present invention provides a character string presenting means for presenting a character string as a sensory stimulus used for measuring an evoked potential, a character string data recording means for recording data relating to the contents of various character strings,
There is a character string presentation control means for controlling the content of the presented character string and the presentation time. By doing so, it becomes possible to measure not only the objective amount such as the evoked potential but also the subjective amount that represents the subject's judgment about the content of the character string at the same time, and it is possible to continuously measure the objective amount and the subjective amount. Since the time required is shortened, the burden on the subject can be reduced.

Furthermore, according to the present invention, a character string presentation control means for controlling presentation of a character string, an evoked potential recording control means for controlling storage of measured brain potentials, a character string presentation control means and an evoked potential recording control means are provided. There is an evoked potential measurement procedure control means that controls according to the measurement procedure of the measurer. By doing so, the procedure for obtaining the evoked potential is automated, and the burden on the experimenter can be reduced.

〔Example〕

 An embodiment of the evoked potential measuring device of the present invention is shown in FIG.

The character string presentation unit 11 presents a character string to the subject 10 based on the character string data 131 output from the character string presentation control unit 13. The character string data storage unit 12 stores the data of the character string to be presented to the subject 10, inputs the signal 132 designating the character string data output from the character string presentation control unit 13, and the character designated by the signal. The column data 121 is output. The character string presentation control unit 13 uses the signal 181 regarding the presentation time of the character string and the content of the character string output from the evoked potential measurement procedure control unit 18, and uses the signal 181 to specify the character string data in the character string data storage unit 12. 132 is output, and the character string data 121 output from the character string data storage unit 12 at the determined time is output to the character string presentation unit 11 as the character string data 131. The evoked potential measurement unit 14 amplifies the brain potential input via the electrode 19 and, if necessary, performs preprocessing such as a frequency filter for noise elimination, and outputs a brain potential signal 141. The evoked potential recording control unit 16 uses the signal 182 regarding the evoked potential measurement start time and end time output from the evoked potential measurement procedure control unit 18 and the signal 141 regarding the brain potential output from the evoked potential measurement unit 14, From the time when the recording of the potential starts until the time when it ends, the evoked potential recording unit
The signal 161 relating to the brain potential is output to 15. The evoked potential recording unit 15 inputs the signal 161 relating to the brain potential output from the evoked potential recording control unit 16 and records / holds it. The evoked potential analysis unit 17 uses the signal 151 relating to the brain potential recorded in the evoked potential recording unit 15 and the signal 183 relating to the number of measurements output from the evoked potential measurement procedure control unit 18 to add the measured brain potential. Then, the average value is obtained, characteristic parameters such as latency and amplitude of the evoked potential are extracted, and if necessary, signal processing such as frequency analysis is performed. Evoked potential measurement procedure control unit
18 outputs a signal 181 related to the presentation time of the character string and the content of the character string, a signal 182 related to the evoked potential measurement start time and the end time, and a signal 183 related to the number of measurements according to the measurement procedure set by the measurer.

On the other hand, the subject 10 inputs the result of subjective judgment on the character string presented by the character string presenting section 11 into the subjective quantity input section 20. The input signal 201 relating to the subjective amount is collected by the subjective amount data collecting unit 21. The subjective data analysis unit 22
A signal 133 related to the presentation order of the character strings output from the character string presentation control unit 13, and output from the subjective amount data collection unit 21, with respect to the judgment of the subject with respect to the content of the given character string, in the category designated in advance. Based on the signal 211 representing the corresponding numerical value, how the subject feels regarding the content of the character string is analyzed. The objective quantity / subjective quantity relation analysis unit 23, based on the signal 171 related to the objective quantity data output from the evoked potential analysis unit 17 and the signal 221 related to the subjective quantity data output from the subjective quantity data analysis unit 22, Analyze the relationship of subjectivity.

Next, an example of fatigue level measurement in an actual VDT work will be described. For example, every 30 minutes during 2 hours of VDT work, the visual evoked potential using the test item used for the subjective symptom test for VDT fatigue as the sensory stimulus of the character string is measured, and the time change is examined. For example, as the character string presenting unit 11,
A simple type taxiscope as shown in FIG. 2 can be used. The subject looks into the viewing hole 24 with both eyes.
Strobe 25 is used as the light source. When the strobe 25 is turned on, the inspection item on the dial 26 can be seen. At that time, the subject makes a subjective judgment regarding the presented inspection items.
A CRT display can be used as the dial 26. Further, as the character string data storage unit 12, for example,
A magnetic disk device or an optical disk device is used. As the subjective quantity input section 20, for example, a push button switch as shown in FIG. 3 can be used. Before the start of the experiment, the subject is shown an evaluation scale of the degree of fatigue as shown in FIG. 4, and, for example, when the test item "eyes tired" is presented on the dial 26, the eyes are not tired at all. If the user feels that the push button switch should not be pressed, or if the eyes feel quite tired, the push button switch should be pressed twice in succession. A personal computer can be used as the subjective amount data collection unit 21 and the subjective amount data analysis unit 22. Evoked potential measurement procedure department
For example, a personal computer or the like is used as 18. The measurer causes the evoked potential measurement procedure control unit 18 to measure the brain potential after the strobe light is emitted,
Set the measurement procedure by inputting the number of times to emit light to measure the evoked potential (corresponding to the number of test items for subjective symptoms). When the various settings related to the measurement procedure are completed, the electrode 19 is attached to, for example, the earlobe as a portion of the scalp corresponding to the visual cortex in the occipital lobe of the subject and the O-bolt point. When the preparation for the measurement is completed, the visual evoked potential is measured before the VDT work and 30, 60, 90, 120 minutes after the start of the work. The measurement proceeds according to the procedure set in the evoked potential measurement procedure control unit 18. The signal of the brain potential during a set period (for example, 3 seconds) after the strobe 25 emits light is transmitted to the evoked potential recording unit 15, for example, a magnetic disk device, a magnetic tape device or the like via the evoked potential recording control unit 16. Will be recorded. The test item is given to the subject at the same time as the stroboscopic light emission, and the subject inputs the result of the subjective judgment on the presented test item to the subjective amount input unit 20. A signal 131 indicating an instruction to present the next test item from the evoked potential measurement procedure control unit 18 in synchronization with the signal 202 relating to the subjective amount output from the subjective amount input unit 20.
Is transmitted to the inspection item presentation control unit 13. Upon receiving the signal 131 representing the inspection item presentation command, the inspection item presentation unit 11 emits the next light. The above procedure is repeated for the number of test items in the VDT fatigue symptom test. When the measurement is completed a set number of times, the evoked potential analysis unit 17, for example, the personal computer, based on the data of the brain potential of each time recorded in the evoked potential storage unit 15, the same time after the strobe 25 is emitted. Brain potentials are added, the average value of each is calculated, and the characteristic parameters of the evoked potential (for example, latency and amplitude) are automatically calculated. On the other hand, the data regarding the subjective amount input by the subject using the push button switch is collected in the subjective amount data collection unit 21. Subjective data analysis section
Reference numeral 22 denotes a signal 133 regarding the presentation order of the inspection items output from the inspection item presentation control unit 13, and a signal 211 representing a numerical value corresponding to a given pre-specified category output from the subjective amount data collection unit 21. Based on the analysis, it is analyzed which test item the test subject feels fatigue and to what extent. Fatigue degree analysis unit 23, based on the signal 171 regarding the objective amount data of the fatigue degree output from the evoked potential analysis unit 17 and the signal 221 regarding the subjective amount data of the fatigue degree output from the subjective amount data analysis unit 22, Analyze the relationship between objective quantity and subjective quantity in measurement. For example, it is possible to obtain the correlation coefficient between the subjective quantity and the objective quantity.

If necessary, the evoked potential analysis unit 18 performs frequency analysis and power analysis of the obtained evoked potential.

〔The invention's effect〕

By using the present invention, it becomes possible to simultaneously perform the measurement of evoked potential and the subjective symptom test in the measurement of VDT fatigue, and the burden on the subject is reduced by eliminating the increase in measurement time caused by continuously performing both. Further, it is possible to eliminate the influence of the measurement time on the factor of VDT fatigue. In addition, since the measurement procedure is automated, the burden on the measurer can be reduced.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of the present invention, FIG. 2 is a configuration diagram illustrating a character string presentation unit in FIG. 1, and FIG. 3 is an example of a subjective amount input unit in FIG. FIG. 4 is a perspective view of FIG.
FIG. 5 is a diagram showing an evaluation scale used for subjective evaluation of fatigue in the embodiment of the figure, and FIG. 5 is a basic configuration diagram of an evoked potential measuring device according to a conventional technique. 11 ... Character string presenting unit, 12 ... Character string data storage unit, 13 ... Character string presenting control unit, 14 ... Evoked potential measuring unit, 15 ... Evoked potential recording unit, 16 ... Evoked potential recording control unit, 17 ... Evoked potential analysis Department, 18
... Evoked potential measurement procedure section, 19 ... Electrodes, 20 ... Subjective quantity input section, 21 ... Subjective quantity data collection section, 22 ... Subjective quantity data analysis section, 23 ... Objective quantity / subjective quantity relationship analysis section, 121 ... Character string data , 131 ... A signal indicating a test item presentation command, 132 ... A signal specifying character string data, 141 ... A signal related to brain potential, 151
… Brain potential signals, 161… Brain potential signals, 181
... Signal presentation time and content signal, 182 ... Evoked potential measurement start time and end time signal, 183 ...
Signal about the number of times of measurement, 24 ... The light that the subject looks into, 25
... Strobe, 26 ... Dial, 51 ... Visual stimulus presentation section, 52 ... Amplifier, 53 ... Monitor, 54 ... Pulse generator, 55 ... Adder,
56 ... XY recorder, 57 ... Electrode.

Claims (1)

[Claims] 1. A character string presenting means for presenting a character string representing some test item as a sensory stimulus given to a subject, a character string data storage means for storing data relating to the content of the character string presented to the subject, and a character to be presented. Character string presentation control means for controlling the content of the string and the presentation time, a subjective amount input means for inputting a subjective judgment regarding the content of the presented character string, and data output from the subjective amount input means are collected. Subjective amount data collection means, subjectivity amount data output from the subjectivity amount data collection means, and subjectivity amount data that quantitatively expresses the subjective amount data output from the character string presentation control means. Analyzing means, evoked potential measuring means for measuring and amplifying the electroencephalographic potential evoked by the presented character string, of the brain potential signal output from the evoked potential measuring means The evoked potential memory control means for controlling existence, the evoked potential recording means for recording the brain potential signal output from the evoked potential memory control means, and the brain potential using the brain potential signal output from the evoked potential recording means Evoked potential analysis means for obtaining the addition and average value of the evoked potentials and extracting characteristic parameters including the evoked potential latency and amplitude, and the character string presentation control means and evoked potential memory control means according to the procedure for measuring the evoked potentials, An evoked potential measurement procedure control means for controlling the evoked potential analysis means, an evoked potential output from the evoked potential analysis means based on a characteristic parameter and a subjective amount related to the content of a character string output from the subjective quantity data analysis means. And an objective quantity / subjective quantity analyzing means for analyzing the relationship between the subjective quantity and the subjective quantity.