JP2011212041A - Device and method for measuring flicker value - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for measuring flicker values applicable to evaluating the quantitative change of a brain function.SOLUTION: The device for measuring flicker values, having a control means, a display means, and an operating means, the display means blinks and displays the OFF period of the display while changing the same by 1/ffluctuation, the display means monotonously increases or decreases the index n of the 1/ffluctuation or a flickering frequency, is characterized in that the control means decides the index n or the flickering frequency as the flicker value when the operating means is operated and a predetermined signal is transmitted from the operating means to the control means in the case the state where a subject can not perceive the flicker of the display by the display means is changed to the state where the subject can perceive the same or in the case the state where the subject can perceive the flicker of the display by the display means is changed to the state where the subject can not perceive the same.

Description

  The present invention relates to a flicker value measuring apparatus and measuring method applicable to evaluation of qualitative changes in brain function.

It is known that 1 / f fluctuation affects human senses, that is, brain function, and various studies have been conducted. As one of them, the following Non-Patent Documents 1 and 2 disclose the influence of 1 / f ⁿ fluctuation on hearing. In the present specification, 1 / f ⁿ fluctuation (n is a real number greater than or equal to 0) means that the amplitude of the frequency f constituting the temporally changing signal changes by 1 / f ⁿ .

In Non-Patent Document 1, the auditory stimulation interval is changed by 1 / f ⁰ fluctuation, 1 / f ¹ fluctuation, 1 / f ² fluctuation, and 1 / f ^∞ fluctuation (actually, there is no fluctuation at a constant interval). The N100m component of the human auditory evoked magnetoencephalographic response and the process of habituation to the stimulus have been studied. It is disclosed that it is influenced by. As the fluctuation generation method, the method disclosed in Non-Patent Document 3 is used.

Non-Patent Document 3 discloses that a predetermined frequency spectrum can be defined and subjected to inverse Fourier transform to generate a fluctuation acoustic signal. For example, FIG. 10 shows frequency spectra (power spectra) corresponding to fluctuations of 1 / f ⁰ , 1 / f ¹ , 1 / f ^2.5 , and 1 / f ³ , and is generated from them. A time-varying signal is shown in FIG. In FIG. 11, the signal waveforms of (a) to (d) correspond to fluctuations of 1 / f ⁰ , 1 / f ¹ , 1 / f ^2.5 , and 1 / f ³ , respectively.

  Non-Patent Document 2 discloses the influence of the auditory evoked magnetoencephalogram response on the mismatch response. A mismatch response is a response that occurs when a different stimulus is presented infrequently among the stimuli that are presented frequently. It is believed that destruction by low frequency stimulation is a prerequisite for the formation of a mismatch reaction. Specifically, under the same stimulus interval conditions as in Non-Patent Document 1, standard stimulus 1 KHz that promotes prediction and formation of a memory trace with a probability of 80%, and departure stimulus 2 KHz that performs prediction and destruction of a memory trace with a probability of 20% Presenting a pure tone with a duration of 100 ms to a person, measuring the auditory evoked magnetoencephalographic response to 1 KHz and 2 KHz sound stimuli, and disclosed that the activity intensity of the mismatch reaction was affected by fluctuation Yes. As the fluctuation generation method, the method disclosed in Non-Patent Document 3 is used.

JP 2008-220639 A JP 2008-301841 A

“Hearing-induced magnetoencephalographic response due to 1 / fn fluctuations in stimulus interval”, Yoshiyoshi Harada et al., Journal of Biomagnetic Society of Japan, Vol.13, No.2 (2000), 1-11 “The effect of 1 / f fluctuation in inter-stimulus intervals on auditory evoked mismatch field”, Nobuyoshi Harada et al., Neuroscience Letters, 379 (2005), 223-228. “Fractal”, Hideki Takayasu, Asakura Shoten, 1986, pp. 23-25, pp. 110-112

  The inventor of the present application has proposed a method that replaces the conventional flicker test in order to measure human mental fatigue (see Patent Documents 1 and 2). However, it is not easy to use these methods to evaluate qualitative changes in human brain function, which is wider than human mental fatigue.

  In addition, qualitative changes in human brain function have been studied using magnetoencephalograms, but measurement of magnetoencephalograms requires expensive equipment and is not easy to measure.

  In addition, the above Non-Patent Documents 1 and 2 are researches on auditory stimuli, and the methods disclosed in Non-Patent Documents 1 and 2 are not easy to apply to visual stimuli, and more widely the quality of human brain function. It is not a method that can be used to evaluate changes.

  The present invention has been made to solve the above-described problems of the prior art, and is a flicker value measuring apparatus and measurement that can be widely used for evaluating qualitative changes in brain function, including human mental fatigue. It aims to provide a method.

The present inventor has conceived the possibility of flicker value is affected by 1 / f ⁿ fluctuation, therefore, presents a blink stimuli including 1 / f ⁿ fluctuation, by looking at the flicker perception of human brain function Based on the idea that qualitative changes can be evaluated, the present invention has been achieved.

That is, the first flicker value measuring apparatus according to the present invention comprises a control means, a display means, and an operation means,
The display means blinks and displays the display OFF period with 1 / f ⁿ fluctuation,
The display means monotonously increases or decreases the 1 / f ⁿ fluctuation index n;
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized Means is operated, a predetermined signal is transmitted from the operation means to the control means,
The control means determines the index n when the signal is received as a flicker value.

The second flicker value measuring apparatus according to the present invention is:
A control means, a display means, and an operation means,
The display means blinks and displays the display OFF period with 1 / f ⁿ fluctuation,
The display means monotonously increases or decreases the blinking frequency;
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized Means is operated, a predetermined signal is transmitted from the operation means to the control means,
The control means determines the flicker frequency when the signal is received as a flicker value.

A third flicker value measuring apparatus according to the present invention is the above first or second flicker value measuring apparatus,
The 1 / f ⁿ fluctuation is
Fluctuation in which the frequency spectrum of the change in the OFF period changes by 1 / f ⁿ under the condition that the average blinking frequency becomes constant, or
In the state where the blinking period does not change, the frequency spectrum of the change in the OFF period is a fluctuation that changes by 1 / f ⁿ .

The first flicker value measuring method according to the present invention is:
Display means, while flashing in conditions OFF period of the display is changed by 1 / f ⁿ fluctuation monotonically increase or decrease the exponent n of the 1 / f ⁿ fluctuation,
When the subject changes from a state where the flickering of the blinking display by the display means cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display means can be recognized to an unrecognizable state It is characterized in that n is determined as a flicker value.

The second flicker value measuring method according to the present invention is:
The blinking frequency is monotonously increased or decreased while the display means blinks on the condition that the OFF period of the display changes with 1 / f ⁿ fluctuation.
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized The frequency is determined as a flicker value.

A third flicker value measuring method according to the present invention is the above first or second flicker value measuring method,
The 1 / f ⁿ fluctuation is
Fluctuation in which the frequency spectrum of the change in the OFF period changes by 1 / f ⁿ under the condition that the average blinking frequency becomes constant, or
In the state where the blinking period does not change, the frequency spectrum of the change in the OFF period is a fluctuation that changes by 1 / f ⁿ .

A fourth flicker value measuring method according to the present invention is the above-described third flicker value measuring method,
As the index n, at least a first value between 0 and 1, a second value larger than 1, and a third value larger than the first value and smaller than the second value. The blinking frequency determined by using is recorded.

According to the present invention, it is possible to determine an index n or a frequency that is a threshold for flicker recognition under 1 / f ⁿ fluctuation.

  The determined threshold index n or threshold frequency can be used to evaluate a person's mental fatigue, and can be more widely used to evaluate a qualitative change in a person's brain function.

  In particular, if a threshold frequency is measured for a plurality of indices n and a change pattern of the threshold frequency corresponding to the magnitude of the index n is analyzed, a qualitative change in human brain function can be evaluated in more detail and accurately. . That is, it is possible to easily evaluate qualitative changes in human brain function easily and inexpensively without using an expensive magnetoencephalographic measurement apparatus that is difficult to handle.

For example, fatigue includes high-order fatigue and peripheral function fatigue of the cerebral cortex, and these can be determined by the present invention. In the auditory reaction, a component after 100 ms, which has a slow latency in which the reaction appears, is considered to be a component representing a higher-order reaction (higher-order function) of the cerebral cortex, and shows clear habituation. On the other hand, a component with a latency of 20-30 ms is a peripheral reaction (peripheral function)
And they do not show a clear habituation. In addition, the function of clear habituation in higher-order reactions is also detected as the establishment of “prediction” for the arrival of a stimulus, and the establishment of the “prediction” and its “destruction” are detected as mismatch reactions. Such mismatch reactions are also detected in visual responses, and functional differences for higher order and peripheral function habituation and adaptation also exist in the visual system. Thus, fatigue of higher-order functions and peripheral functions of the cerebral cortex can be detected as a difference in adaptability. Further, as will be described later as Example 3, the flicker recognition threshold for a light stimulus blinking with 1 / f ⁿ fluctuation is an index reflecting human adaptability to the light environment. Therefore, the method of decreasing the threshold value in a small or large region where the exponent n of 1 / f ⁿ fluctuation (the exponent n of the power multiplier f ⁿ and simply referred to as “power”) is uniform, or It can be determined whether the fatigue is occurring in a peripheral function or a higher-order function based on the difference. In addition, the degree of contribution in the deterioration of the nervous system in fatigue of peripheral functions and higher-order functions is determined by determining how much the threshold value decreases as the power n increases compared to the uniform case. be able to.

Further, according to the present invention, it is possible to discriminate between a healthy person and a schizophrenic patient and judge the degree of progression of the disease state. As will be described later as an example, the adaptation process reflects the influence of the power n of 1 / f ⁿ fluctuation of the stimulation interval of the flashing light. That is, if the person is a healthy person, the flicker value changes greatly (decreases as the power n increases) due to the change of the power n of 1 / f ⁿ fluctuation. However, in the case of schizophrenic patients, this adaptation process is hindered, so the influence of the power n of fluctuation is not reflected, and the flicker value is considered to be flat regardless of the power n.

  In addition, a phenomenon called memory trace is known as a phenomenon in which Sensory Gating failure, which is a typical finding of schizophrenia, is developed in the time-series region of stimulation. When a different stimulus is presented after a certain stimulus is continued, an evoked response having a significantly different waveform is detected, which is different from the response obtained with the continuous stimulus. This is called a mismatch reaction. In contrast to the formation of “prediction” in the broad sense formed by continuous stimuli, the reaction formed by the destruction of “prediction” due to the arrival of a stimulus different from the prediction is said to be a mismatch reaction. . The formation of a “forecast” in this process is considered to be the formation of a memory trace. In the case of schizophrenia, the formation of this memory trace appears to be impaired, and it has been reported that the mismatch response is significantly reduced compared to healthy individuals. Since the memory trace is not formed normally, even if different stimuli come, sufficient destruction of the memory trace is not formed, resulting in only a small mismatch reaction.

In a healthy person, the formation of a mismatch reaction is strongly influenced by the power n of 1 / f ⁿ fluctuation of the stimulation interval. In a region where the power n is small, the formation of a memory trace is weak and the mismatch reaction is suppressed. In large areas, the formation of memory traces is promoted, causing an increased mismatch response. On the other hand, in patients with schizophrenia, the formation of a memory trace is basically inhibited, so that the formation of a mismatch reaction is suppressed even in a region where the power n of 1 / f ⁿ fluctuation is large. Is no longer different from the region where the power n is small. That is, a flat result that does not change depending on the power n is obtained. This memory trace formation ability is also considered to reflect the ability to adapt to light stimulation. As a result, in healthy individuals, the result of a large change with power n (decrease with increasing power n) is obtained, and patients with schizophrenia It is considered that a flat result without change is obtained without depending on the power n.

Thus, when the stimulation interval is varied with 1 / f ⁿ fluctuation and the value of the power n is changed, the subject is a healthy person depending on whether the flicker value changes for each power n or is flat. Or a patient with schizophrenia. Moreover, it can be used for the diagnosis of the degree of progression of symptoms in schizophrenic patients depending on how much the change has changed compared to a flat case.

It is a block diagram which shows the flicker value measuring apparatus which concerns on embodiment of this invention. It is a flowchart which shows the 1st measuring method using the flicker value measuring apparatus shown in FIG. It is a graph which shows the time change of a stimulation interval. It is a flowchart which shows the 2nd measuring method using the flicker value measuring apparatus shown in FIG. Is a graph showing the relationship between index n and the threshold frequency of flicker perception of 1 / f ⁿ fluctuation. It is a graph which shows the pattern according to the qualitative change of brain function. A plurality of subjects is a graph showing the result of measuring the threshold frequency cognitive flicker under the conditions of 1 / f ⁿ fluctuation. A plurality of subjects is a graph showing the percentage of people who feel a flicker upon presenting stimulation sequence under conditions of 1 / f ⁿ fluctuation. The light stimulus flashes under conditions of 1 / f ⁿ fluctuation is a graph showing a magnetoencephalography measured presented to the subject. Is a graph showing the spectrum of the 1 / ^{f n} fluctuation. It is a graph which shows the fluctuation signal corresponding to each spectrum shown in FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a flicker value measuring apparatus according to an embodiment of the present invention. The measurement apparatus includes a display unit 1 that blinks and presents light to the subject T, a control unit 2 that supplies a signal for causing the display unit 1 to blink, and a predetermined operation in response to an operation by the subject T. And an operation unit 3 for transmitting the information to the control unit 2.

  The display unit 1 is a device that can display a two-dimensional image such as a CRT display or a liquid crystal display, or a point light source device such as an LED. The control unit 2 includes an interface corresponding to the display unit 1, and supplies a signal for operating the display unit 1 to the display unit 1 through the interface. Therefore, the control unit 2 also includes a driver corresponding to the display unit 1, for example, a display driver, an LED driver, and the like. The operation unit 3 can use a switch and computer operation means (keyboard, mouse, etc.). The control unit 2 also includes an interface (not shown) for receiving a signal (information) from the operation unit 3. Further, the control unit 2 includes an arithmetic device for executing processing to be described later, a data storage device, and the like. Therefore, for example, a computer can be used as the control unit 2.

The outline of the operation of this measuring apparatus will be described as follows.
First, the control unit 2 supplies a signal whose amplitude changes with time to the display unit 1, changes the luminance of the display unit 1, and causes the display unit 1 to blink. If the display unit 1 is a display capable of displaying a two-dimensional image, a predetermined area is blinked. In this state, the subject T operates the operation unit 3 to notify the control unit 2 whether or not the blinking display on the display unit 1 has been recognized as flicker. Whether or not the flicker is recognized is received by the subject T, and predetermined data is transmitted from the operation unit 3 to the control unit 2 and is detected by the control unit 2. Then, the control part 2 supplies the signal from which the change state of an amplitude differs to the display part 1, and repeats the process which detects whether the test subject T recognized flicker similarly. When the subject T changes from a state in which flicker cannot be recognized to a state in which flicker can be recognized, or changes from a state in which flicker can be recognized to a state in which flicker cannot be recognized, the control unit 2 records the blinking display condition at that time. .

  Next, the flicker value measuring method according to the embodiment of the present invention will be specifically described. Below, it demonstrates as a process which the control part 2 performs unless there is particular notice. The control unit 2 reads necessary data from the internal recording device to an internal storage device (hereinafter also referred to as a memory), performs processing using a predetermined area of the memory as a work area, The processing result is appropriately recorded in a recording device. Further, it is assumed that initial conditions necessary for measurement are recorded in advance in a recording device inside the control unit 2.

  First, a method for measuring the first flicker value will be described. FIG. 2 is a flowchart showing a first method of measuring the flicker value using the apparatus shown in FIG.

In step S1, initial conditions are read from the recording means and initial setting is performed. The initial conditions are the blinking frequency f0, the fluctuation index (power) n, the fluctuation index increment Δn, and the display time τ. Here, f0 = 140 (Hz), n = 0, Δn = 0.1, and τ = 5 (seconds). The meaning of setting the frequency f0 to this value will be clarified in the following description, but in brief, the threshold frequency at which a person perceives flickering changes as shown in FIG. 5 due to fluctuation, and f0 = 140.
(Hz) is a frequency at which a normal person cannot recognize flicker when the stimulation interval is randomly changed (corresponding to n = 0 in FIG. 5).

Step S2 Oite, the control unit 2 is the average frequency of the flashing f0 (as one period of the ON period and OFF period), the fluctuation in stimulation interval (OFF period) 1 / ^{f n,} is flashing τ seconds A drive signal for causing the display unit 1 to blink is generated under the condition of sustaining and is transmitted to the display unit 1. For example, when the display unit 1 displays with brightness corresponding to the amplitude of the input analog signal, the control unit 2 changes the amplitude between 0 and the maximum value at the average frequency f0, and the stimulation interval. Fluctuates at 1 / f ¹ and generates a digital signal D (t) for 5 seconds, which is once recorded in the recording device. Thereafter, the digital signal D (t) is converted into an analog signal A (t) according to the elapse of time t from the disclosure time, and transmitted to the display unit 1. Thereby, as described above, the display unit 1 blinks for 5 seconds. When step S2 is executed for the first time, the fluctuation is 1 / f ⁰ , which means that the stimulation interval changes randomly.

A specific example of the output signal from the control unit 2 is shown in FIG. In FIG. 3, as a reference, a waveform with no fluctuation and a constant frequency is shown in FIG. In FIG. 3B, a period t0 (= 1 / (2 × f0) = 1/280 (seconds) in which the signal takes 0 (OFF display) or the maximum value (ON display) and the signal takes the maximum value. as certain conditions under which the average frequency is f0 (i.e., 1 / (conditions mean value of the ON period + OFF period) it is f0) by, changing the OFF period (stimulation interval) t1 at 1 / ^{f n} fluctuation. A method for generating 1 / f ⁿ fluctuation is well known, and for example, the method described in Non-Patent Document 3 may be used as in Non-Patent Documents 1 and 2. In this case, for example, the OFF period t1 is changed according to the amplitude of the waveform shown in FIG. Average frequency is OFF
The average value of the period t1 can be determined. For example, the average value of the OFF period t1 is determined by determining the maximum value and the minimum value of the fluctuation waveform during the display time τ (here, 5 seconds) as the actual values. The average value S / τ of the integral value S of the waveform at time τ can be obtained.

In step S3, the control unit 2 determines whether or not the subject T has recognized the flicker. For example, when data from the operation unit 3 is waited and is not received even after a predetermined time has elapsed, the process proceeds to step S4, and when received, the process proceeds to step S5. For example, if the subject T is instructed in advance to operate the operation unit 3 when recognizing flickering and not operate the operation unit 3 when recognizing flickering, the control unit 2 does not receive a signal. It can be determined that the subject T does not recognize the flicker.

  In step S4, the fluctuation index n is increased by an increment value n of the fluctuation index, and the process proceeds to step S2.

  Thereafter, steps S2 to S4 are similarly repeated, and when it is determined that the flicker is recognized in step S3 as described above, the process proceeds to step S5, and the fluctuation index n is recorded as the flicker value in step S5, and the process is ended. .

As described above, the fluctuation index n (for example, n1 in FIG. 5) when the subject T can recognize the flicker from the state in which the flicker cannot be recognized can be determined as the flicker value. Therefore, if the fluctuation index (flicker value) obtained by the above measurement is recorded for a specific person in a healthy state without fatigue, the fluctuation index will be measured for the same person at a later date. By comparing these values, it is possible to determine a qualitative change in the brain function at the time of measurement of the person, for example, a fatigue state. If the fluctuation index (flicker value) is lower than a normal value by a predetermined value or more, it can be determined that the user is tired.

Note that the present invention is not limited to the measurement method described above, and f0 = 140 (Hz), Δn = 0.1, n = 1 may be used as an initial condition, and n may be increased from 1 (see FIG. 5). In this case, the subject T becomes in a state where the flicker cannot be recognized when n is increased from 1 from the state where the flicker can be recognized first. Therefore, in this case, the index n when the flicker is not recognized from the state where the flicker is recognized is recorded as the flicker value.

Similarly to the above, f0 = 140 (Hz), Δn = 0.1, n = 1 may be used as an initial value, and n may be decreased from 1 (see FIG. 5). In this case, in step S4, n is decreased by Δn, that is, a new n is determined by n = n−Δn. Also in this case, the subject T enters a state where it cannot be recognized when n is decreased from 1 from the state where the flicker can be recognized first. Accordingly, also in this case, the index n when no flicker is recognized is recorded as the flicker value.

Thus, the initial value of frequency f0, n, and the increase / decrease of n can be set suitably. That is, when the state where the flicker can be recognized is changed to a state where the flicker cannot be recognized by changing n, or the state where the flicker can be recognized from the state where the flicker is not changed can be recognized. Initial conditions may be set so that recording is possible, and there are four types of changing methods as indicated by the arrows along the curve in FIG. In other words, whether n is increased from around n = 0 or n is decreased from a value greater than 1, n is decreased from the condition that the threshold frequency takes the maximum value (n is about 1) or It may be increased. In any case, the index n when the flicker recognition state changes may be recorded.

  The frequency f0 may be set according to the subject to be measured. Further, the blinking time t0 is not limited to the above value, and is arbitrary.

  Next, a method for measuring the second flicker value will be described. FIG. 4 is a flowchart showing a second method of measuring the flicker value using the apparatus shown in FIG. The second method is a method of measuring a threshold frequency at which flicker can be recognized under three or more different types of fluctuation conditions.

In step S11, initialization is performed in the same manner as in step S1. However, unlike step S1, the initial value of the frequency f1 to be changed, the frequency increment Δf, the upper limit value of the frequency, and three or more fluctuation indexes n are set.

  In step S12, one fluctuation index n is selected from a plurality of fluctuation indices.

In step S13, using the selected fluctuation index n in step S12, so that the average frequency is f1, flickers the display of the display unit 1 at 1 / f ⁿ fluctuation. The method for generating the 1 / f ⁿ fluctuation signal is the same as the first method. The generated signal is once recorded in the recording device, and is output to the display unit 1 in accordance with the elapsed time t from the disclosure time.

In step S14, the control unit 3 waits for a signal indicating that the subject T can no longer recognize the flicker. If it is not received even after the predetermined time has elapsed, the process proceeds to step S15. If it is received within the predetermined time, the process proceeds to step S17, and the frequency f1 at that time is recorded as a flicker value corresponding to the index n, and then the process proceeds to step S18.

In step S15, it is determined whether or not the current frequency f1 is equal to or higher than the upper limit value. If it is equal to or higher than the upper limit value, the process proceeds to step S18. If it is not equal to or greater than the upper limit value, the frequency f1 is increased by Δf in step S16, and the process proceeds to step S13.

In step S13, using the fluctuation index n again, the display unit 1 is blinked and displayed with 1 / f ⁿ fluctuation so that the average frequency becomes the newly set f1, and in step S14, the operation unit 3 Wait for a signal to indicate that the subject has recognized the flicker. As described above, in step S14, steps S13 to S16 are repeated until a signal indicating that the subject no longer recognizes flicker is received or the frequency becomes equal to or higher than the upper limit value.

In step S18, it is determined whether or not the measurement has been completed for all the indices n specified in step S11. If there is an index n that is not used, the frequency f1 is returned to the initial value, and the process returns to step S13. Then, an unused index n is selected and steps S13 to S17 are repeated. If the measurement has been completed for all of the indices n, the process ends.

As described above, for each of a plurality of n, the frequency at which the subject T cannot recognize the flicker when blinking with 1 / f ⁿ fluctuation can be determined as the flicker value.

  Therefore, for a specific subject, the above measurement is performed in a normal state, and the obtained result (threshold frequency) is recorded in correspondence with the index n, and the same measurement is performed later using the same index n. Thus, by analyzing how the obtained plurality of threshold frequencies change from the corresponding normal values, it is possible to evaluate the qualitative change in the brain function of the subject at that time.

As the index n, for example, four types of n = 0, 1, 2, and ∞ can be used. When blinking with a 1 / f ⁿ fluctuation signal, the frequency at which the flicker can be recognized becomes the largest when 1 / f ¹ fluctuation as shown in FIG. However, the frequency at which flicker is perceived decreases. Accordingly, the index n is not limited to these, and three or more different indices n including at least 1 or a value close to 1, a value between 0 and 1, and a value between 1 and ∞ are included. If used, pattern changes can be analyzed. Furthermore, without using a value close to 1 as the index n, the first value between 0 and 1, the second value greater than 1, the greater than the first value, and the second value A third value smaller than the value may be used.

An example is shown in FIG. In FIG. 6, 1 / f ⁰ , 1 / f ¹ , 1 / f ² , and 1 / f ^∞ are used. In FIG. 6, a black bar graph and a white bar graph are measurement values relating to the same person, but are measurement values in different states. For example, a black bar graph is a value measured in a normal state. Therefore, if the degree of decrease in these values is evaluated, qualitative changes in brain function can be evaluated. As shown in FIG. 6, the assumed change pattern includes a pattern (a) that decreases at a substantially constant rate in any case, and a pattern (b) that increases the decrease rate when n is large. , A pattern (c) in which the decrease rate becomes larger when n is small is considered.

  In the case of decreasing in parallel as in the pattern (a), that is, in any of exponents (powers) n = 0, 1, 2, and ∞, there is no difference in the way of change, and the same frequency or the same frequency In the case of decreasing by the ratio, this state is considered to be a state in which the influence of the power n of fluctuation does not affect the way of change and the basic function of the brain is reduced.

  As in pattern (b), when the amount of change frequency or the change frequency ratio is small when the power n is small and increases as the power n increases, the value of the power n positively affects the change in the threshold value. It is thought that there is. It is considered that the increase in regularity in the stimulation interval with the increase of the power n positively affected the change in the threshold value under each power condition, that is, the change in the power n of the fluctuation was captured by the change in the brain plasticity. Speaking conversely, it is considered that the qualitative change of the brain that responds to the power n is captured.

  As in the pattern (c), when the amount of change frequency or the change frequency ratio is small, the power n is small, is large at 0 or 1, and decreases as the power n increases, the randomness detection function decreases with the brain function change It can be said that.

  Note that the second method is not limited to the method described above. For example, with a specific fluctuation index n, the frequency is decreased from a high value, and the frequency when the flicker can be recognized from a state where the flicker is not recognized may be recorded.

In any of the first and second methods described above, the fluctuation signal may have a waveform as shown in FIG. That is, the OFF period (stimulus interval) t1 may be changed in a constant state where the blinking cycle (the sum of the ON period and the OFF period) does not change. In this case, the ON period changes in reverse to the OFF period. In the case of the second method, since the blinking frequency is changed, the blinking period is constant only while the frequency does not change, and if the frequency changes, it is determined accordingly.

In both the first and second methods, 1 / f ⁿ fluctuation waveform data is recorded in advance as time-series digital data for each index n, and each time n is changed, it corresponds. Digital data may be read and used.

In either of the first and second methods, the blinking display, that is, the change in luminance is not limited to the digital change as shown in FIG. 3, but may be an analog change. . That is, any waveform may be used as long as a low luminance state corresponding to OFF display and a high luminance state corresponding to ON display are alternately repeated. Even in this case, the OFF period may be changed with 1 / f ⁿ fluctuation as described above.

  Further, as shown in FIG. 1, the display unit, the control unit, and the operation unit may be configured integrally without being separated from each other.

FIG. 7 is a graph showing the result of measuring the flicker recognition threshold by varying the stimulation interval with 1 / f ⁿ fluctuation as in the flowchart shown in FIG. 4 as described above. That is, the stimulation interval is changed by 1 / f ⁿ fluctuation using four kinds of indexes of 0, 1, 2, and ∞ (constant intervals),
The threshold frequency at which a flickering sensation was measured by changing the frequency. FIG. 7 shows the measurement of eight subjects, the measurement results are averaged for each index n, and are represented as a bar graph with error bars.

The average threshold frequency at which flickering occurs is 111.9 Hz for 1 / f ⁰ fluctuation, 164.0 Hz for 1 / f ¹ fluctuation, 81.5 Hz for 1 / f ² fluctuation, 1 / f ^∞ fluctuation (constant interval) It was 46.5Hz. That is, the threshold frequency increases from 1 / f ⁰ fluctuation to 1 / f ¹ fluctuation, and then decreases as 1 / f ¹ , 1 / f ² , 1 / f ^∞ (constant interval) and the exponent n increase. It became clear to go. That is, it turns out that it changes like the curve shown in FIG. Therefore, it can be seen that the results obtained by the first and second measurement methods described above are effective for evaluating a qualitative change in human brain function.

FIG. 8 is a graph showing the results of measurement for eight subjects, as in Example 1. In FIG. 8, the ratio of the person who feels flicker when the average stimulation interval is adjusted to the threshold condition of 1 / f ⁰ and the stimulation train of 5 seconds is presented under each fluctuation condition is shown as a percentage. The percentage of people who feel a flicker, 1 / the ^{f 0} 12.4% 1 / ^{f 1} In 24.1%, 1 / the ^{f 2 4.4%, 1 / f} ∞ ( regular intervals) in 0.03 %Met. Percentage of people who once rise between 1 / f ⁰ and 1 / f ¹ and feel flickering as 1 / f ¹ , 1 / f ² , 1 / f ^∞ (constant interval) and power n increase Was found to decrease.

An experiment for verifying 1 / f fluctuation and adaptability to the light environment is shown below.
In this patent document 2, when presenting the flicker stimulus at a constant interval in the above-mentioned Patent Document 2, when the frequency of the presented light stimulus is lower than the flicker value (flicker recognition) and high (flicker non-recognition), We report that the pupil's response to stimulus missions during the light stimulus sequence changes from a closing shift to an opening shift, and that the light stimulus OFF response increases with increasing frequency in the visually evoked magnetoencephalogram response to the light stimulus sequence. ing.

  It is also known that as the duration of light stimulation and the light intensity increase, the OFF response due to light stimulation increases and the time for blocking alpha waves increases accordingly. Further, it is known that the sensitivity to the change in contrast increases as the adaptation to the light environment increases. That is, as the duration of light stimulation increases and the light intensity increases, the adaptation to the light environment is enhanced, and as a result, the light environment changes from a highly adapted light environment to a large dark environment. Is thought to be caused.

Therefore, it can be considered from the results of Example 1 that the fluctuation pattern itself caused a change in the frequency threshold for flicker recognition, and the presence or absence of flickering reflects the degree of adaptability to light stimulation. That is, it is considered that the flicker recognition threshold can be used as an index reflecting human adaptability to the light environment. The result of Example 1 is that, in the fluctuation condition, the least adaptable is 1 / f ¹ fluctuation, then 1 / f ⁰ fluctuation, 1 / f ² fluctuation, 1 / f ^∞ fluctuation (constant interval). It is thought that the adaptability increases in order. Therefore, in order to verify 1 / f fluctuation and adaptability to the light environment, the following experiment was performed.

Specifically, the measurement of the visual evoked magnetoencephalogram response is performed using continuous flashing light of 1 / f ⁰ fluctuation, 1 / f ¹ fluctuation, 1 / f ² fluctuation, 1 / f ^∞ fluctuation (constant interval) as a visual stimulus. went. The subjects were presented with continuous flashing light whose time interval was changed by these four types of fluctuations, and the ON response and OFF response to the continuous flashing light stimulus were measured. The result is shown in FIG.

FIG. 9 is a summed average waveform in the channel having the largest p100m component in the primary visual cortex region at the back of the visual evoked magnetoencephalogram response by light stimulation having a duration of 1000 ms. As a result of analyzing the observed ON and OFF responses to light stimulation, the following was found. The ON reaction did not differ between the fluctuation conditions. On the other hand, the OFF reaction has the smallest 1 / f ¹ fluctuation condition, and then it becomes clear that the OFF reaction increases in the order of 1 / f ⁰ fluctuation, 1 / f ² fluctuation, 1 / f ^∞ fluctuation (constant interval). It was. A small OFF reaction indicates that adaptation to the light environment of continuous flashing light is hindered, and a large OFF reaction can be considered to be an increase in adaptation to the light environment of continuous flashing light. Therefore, it is considered that the 1 / f ¹ fluctuation condition is the most hindered in adaptation, and then the adaptation to the light environment is performed in the order of 1 / f ⁰ fluctuation, 1 / f ² fluctuation, 1 / f ^∞ fluctuation (constant interval). It was thought to be enhanced. This result was consistent with the change in the frequency threshold of the flicker value under each fluctuation condition (see Example 1) and the change in the flicker recognition probability (see Example 2).

DESCRIPTION OF SYMBOLS 1 Display part 2 Control part 3 Operation part T Test subject

Claims (7)

A control means, a display means, and an operation means,
The display means blinks and displays the display OFF period with 1 / f ⁿ fluctuation,
The display means monotonously increases or decreases the 1 / f ⁿ fluctuation index n;
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized Means is operated, a predetermined signal is transmitted from the operation means to the control means,
The flicker value measuring apparatus, wherein the control means determines the index n when the signal is received as a flicker value. A control means, a display means, and an operation means,
The display means blinks and displays the display OFF period with 1 / f ⁿ fluctuation,
The display means monotonously increases or decreases the blinking frequency;
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized Means is operated, a predetermined signal is transmitted from the operation means to the control means,
The flicker value measuring apparatus, wherein the control means determines the flicker frequency when the signal is received as a flicker value. The 1 / f ⁿ fluctuation is
Fluctuation in which the frequency spectrum of the change in the OFF period changes by 1 / f ⁿ under the condition that the average blinking frequency becomes constant, or
3. The flicker value measuring apparatus according to claim 1, wherein the frequency spectrum of the change in the OFF period is a fluctuation that changes by 1 / f ⁿ in a state in which the blinking period does not change. Display means, while flashing in conditions OFF period of the display is changed by 1 / f ⁿ fluctuation monotonically increase or decrease the exponent n of the 1 / f ⁿ fluctuation,
When the subject changes from a state where the flickering of the blinking display by the display means cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display means can be recognized to an unrecognizable state A method for measuring a flicker value, wherein n is determined as a flicker value. The blinking frequency is monotonously increased or decreased while the display means blinks on the condition that the OFF period of the display changes with 1 / f ⁿ fluctuation.
When the subject changes from a state where the flickering of the blinking display by the display unit cannot be recognized to a state where the flickering can be recognized, or when the subject changes from a state where the flickering of the blinking display by the display unit can be recognized to a state where the flickering cannot be recognized A method for measuring a flicker value, wherein the frequency is determined as a flicker value. The 1 / f ⁿ fluctuation is
Fluctuation in which the frequency spectrum of the change in the OFF period changes by 1 / f ⁿ under the condition that the average blinking frequency becomes constant, or
The flicker value measuring method according to claim 4 or 5, wherein the frequency spectrum of the change in the OFF period changes by 1 / f ⁿ in a state in which the blinking period does not change.   As the index n, at least a first value between 0 and 1, a second value larger than 1, and a third value larger than the first value and smaller than the second value. The flicker value measuring method according to claim 5, wherein the blinking frequency determined by using is recorded.

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