RU2441571C1 - Method for determination of lability of human visual system - Google Patents

Abstract

FIELD: medicine. ^ SUBSTANCE: invention is referred to the area of medicine and medical devices. The test subject is shown the sequences of coupled light pulses with duration of 50 ms and with pulse separation of 150 ms, repeated after constant time interval 1 s. In the first stage the duration of pulse separation in the couple is shortened with the constant speed 20 ms/s until the test subjects defines the moment of subjective merge of two light pulses in the couple into one. In the second stage the duration of pulse separation in the couple is increased with constant speed 2 ms/s until the subjective feeling of separation of two light pulses in the couple. In the third stage the duration of pulse separation in the couple is decreased discretely with the pitch 0.1 ms until the moment of subjective merge of two pulses. The duration of pulse separation in the moment is taken as liminal duration of pulse separation tlim. In the fourth stage the test subject is shown the rhythmic sequence of light pulses with duration 50 ms separated with liminal pulse separation tlim, the duration of pulse separation is decreased discretely with the pitch 0.1 ms until the moment of subjective merge of two pulses. The duration of pulse separation in the moment is taken as critical duration of pulse separation tcr. The lability of vision system (F) is taken as equal to the value of frequency of sequence of rhythmic light pulses in Hz: F=1/(äimp +tcr), where äimp is the duration of light pulse in sec; tcr is critical duration of pulse separation between light pulses in sec, defined on the fourth stage of measurement. ^ EFFECT: method provides for reliable determination of value of vision system lability due to its determination during rhythmic irritation. ^ 1 dwg, 4 dwg, 1 ex

Description

The invention relates to medicine and medical equipment and is intended to determine the lability of the human visual system.

There is a method of determining lability using the critical fusion frequency of light flickers (CFSM). The maximum frequency of rhythmic stimuli (Hz), at which the subject ceases to distinguish the pulsation of light signals and begins to distinguish them with a gradual decrease in the frequency of flickering from maximum to minimum, serves as a measure of lability. For each subject, averaged CSFM values are obtained in 10 samples with the disappearance and in 12 samples with the appearance of the ability to distinguish between pulsations of light signals [1].

The disadvantage of this method is the low accuracy of determining lability due to the lack of a clear transition from the distinction between light flicker to fusion [2].

The closest in technical essence to the proposed method is a method for determining the lability of the visual system by presenting a test subject with a sequence of paired light pulses of a given duration equal to 50 ms, separated by an interpulse interval of 150 ms, repeated at a constant time interval of 1 s, and at the first stage of measurement, the duration the inter-pulse interval between light pulses in a pair is reduced at a given constant speed of 20 ms / s, until the subject determines the moment the objective fusion of two light pulses in a pair into one, at the second measurement stage, the duration of the inter-pulse interval between light pulses in a pair is increased at a given constant speed of 2 ms / s, until the subject determines the moment of subjective sensation of the separation of two light pulses in a pair, at the third measurement stage the duration of the inter-pulse interval between light pulses in a pair is reduced discretely with a given constant step of 0.1 ms, until the subject determines the moment of subjective fusion of two light pulses in a pair of one, the duration of the interpulse interval between light pulses in a pair at a given time is taken as the threshold duration of the interpulse interval t _then , the lability of the human visual system is taken equal to the value of the frequency of light pulses in Hz:

F = 1 / (τ _imp + t _then ),

where τ _imp - the duration of the light pulse;

t _pore is the threshold duration of the interpulse interval between light pulses in a pair, determined at the third measurement stage [3].

The disadvantage of this method is the unreliable determination of lability. This method uses a sequence of paired light pulses separated by an interpulse interval, repeating through a constant time interval. Such a sequence of paired light pulses is not a rhythmic irritation, therefore, the lability determined by this method does not correspond to the accepted measure of lability as the maximum frequency of reactions that the body can reproduce in exact accordance with the rhythm of the applied irritations [4], that is, when they are rhythmically presented.

The technical result of the proposed method for determining the lability of the human visual system is to increase the reliability of the assessment by determining it with rhythmic irritation.

The technical result is achieved by the fact that the test subject is presented with a sequence of paired light pulses of duration 50 ms, separated by an interpulse interval of 150 ms, repeated through a constant time interval of 1 s, at the first stage of measurements, the duration of the inter-pulse interval between light pulses in a pair is reduced at a constant speed 20 ms / s, until the subject determines the moment of subjective fusion of two light pulses in a pair into one, at the second stage of measurements, the duration of the inter-pulse in the interval between the light pulses in a pair is increased at a constant speed of 2 ms / s, until the subject determines the moment of subjective sensation of the separation of two light pulses in a pair, at the third stage of measurements, the duration of the inter-pulse interval between light pulses in a pair is reduced discretely with a constant step of 0.1 ms until the subject determines the moment of subjective fusion of two light pulses in a pair into one, the duration of the inter-pulse interval between light pulses in a pair at a given time is taken as the threshold duration of the inter-pulse interval t _then , and new is that at the fourth stage of measurements the subject is presented with a rhythmic sequence of light pulses of the same duration equal to 50 ms, separated by a threshold inter-pulse interval of t _then , then the duration of the inter-pulse interval between rhythmic light pulses is reduced discretely with a constant in 0.1 ms steps, until the subject determines the moment of subjective fusion of light pulses, the duration of the inter-pulse interval between the rhythmic Skim light pulses in a given time is taken as the critical duration interpulse interval t _cr, lability of the human visual system is taken equal to the value of the repetition frequency of rhythmic pulses in Hz:

F = 1 / (τ _imp + t _cr ),

where F is the lability of the human visual system;

τ _imp - the duration of the light pulse in seconds;

t _cr - the critical duration of the inter-pulse interval between light pulses in seconds, determined at the fourth stage of measurement.

Figure 1 presents a timing diagram of a sequence of paired light pulses presented to determine the lability of the human visual system in the first to third stages of measurement.

Figure 2 presents a timing diagram of the rhythmic sequence of light pulses presented to determine the lability of the human visual system in the fourth stage of measurement.

Figure 3 presents the timing diagram of the change in the duration of the interpulse interval between light pulses when determining the lability of the human visual system.

Figure 4 presents the timing diagrams of two light pulses separated by an interpulse interval t of the _mission , presented to determine the lability of the human visual system in the first and third stages of measurement, and the visual sensations caused by them,

where - figure 4, a is a timing chart of two light pulses separated by an inter-pulse interval t of the _mission , causing a visual sensation of separation of pulses;

- figure 4, b is a timing diagram of the visual sensation of the two light pulses shown in figure 4, a;

- figure 4, c is a timing diagram of two light pulses separated by a threshold inter-pulse interval t _then , at which a subjective sensation of fusion of two light pulses in a pair into one is achieved;

- figure 4, g is a timing diagram of the visual sensation of the two light pulses shown in figure 4, c;

- τ ₁ - time of visual sensation - the time between the moment of exposure of light to the retina and the moment of occurrence of the corresponding visual sensation [5, 6] (Fig. 4, b, d);

- τ ₂ - recovery time - the time between the moment of termination of the effect of light on the retina and the moment the corresponding visual sensation disappears [5, 6] (Fig. 4, b, d).

The proposed method for determining the lability of the human visual system is as follows.

The test subject is presented with a sequence of paired light pulses of duration τ _imp equal to 50 ms, separated by an initial interpulse interval of duration t _nii equal to 150 ms, repeated through a constant time interval T equal to 1 s (Fig. 1; Fig. 3, time interval 0- T ₁ ).

At the first stage of measurements, the duration of the initial interpulse interval t _n between the light pulses in a pair is reduced with a constant speed V ₁ equal to 20 ms / s (Fig. 3, the time interval T ₁ -T ₂ ), until the subject determines the moment of subjective fusion of two light pulses in a pair of one (figure 3, time T ₂ ).

At the second measurement stage, the duration of the inter-pulse interval t of the _mission between the light pulses in a pair is increased with a constant speed V ₂ equal to 2 ms / s (Fig. 3, the time interval T ₃ -T ₄ ), until the subject determines the moment of subjective sensation of the separation of the two light pulses in a pair (figure 3, time T ₄ ).

At the third stage of measurements, the duration of the interpulse interval t of the _mission between the light pulses in a pair is reduced discretely with a given constant step of 0.1 ms (Fig. 3, the time interval T ₅ -T ₆ ), until the subject determines the moment of subjective fusion of two light pulses in a pair in one (figure 3, time point T ₆ ). The duration of the inter-pulse interval t of the _mission between the light pulses in the pair at time T _{6 is} taken as the threshold duration of the inter-pulse interval of t _then .

In the fourth stage of measurements, the subject is presented with a rhythmic sequence of light pulses of duration t _imp equal to 50 ms, separated by a threshold inter-pulse interval t _then (Fig. 2; Fig. 3, time interval T ₆ -T ₇ ).

Then, the duration of the interpulse interval t of the _mission between the rhythmic light pulses is reduced discretely with a constant step of 0.1 ms (Fig. 3, the time interval T ₇ -T ₈ ), until the subject determines the moment of subjective fusion of the light pulses (Fig. 3, time T ₈ ). The duration of the inter-pulse interval between rhythmic light pulses at time T _{8 is} taken as the critical duration of the inter-pulse interval t _cr , which is fixed at time T ₉ (Fig. 3).

The lability of the human visual system is taken equal to the value of the pulse repetition rate in Hz:

F = 1 / (τ _imp + t _cr ),

where F is the lability of the human visual system;

τ _imp - the duration of the light pulse in seconds;

t _cr - the critical duration of the inter-pulse interval between light pulses in seconds, determined at the fourth stage of measurement.

The lability of the human visual system is due to its inertia, that is, the presence of visual sensation time τ ₁ and recovery time τ ₂ .

When a subject presents two light pulses with a duration of τ _imp > τ ₁ separated by an interpulse interval t of a _mission > t _then (Fig. 4, a), he experiences a subjective sensation of separation of two light pulses (Fig. 4, b). With a decrease in the duration of the interpulse interval t of the _mission between two light pulses to a value of t _mission = t _then (Fig. 4, c), the subject experiences a sensation of subjective merging of two light pulses into one (Fig. 4, d).

During the action of a light stimulus, receptive fields (RP) of neurons undergo three phases of rearrangement. During the first phase with a duration of the order of 10 ms, the spatio-temporal accumulation of signals and the formation of the excitation zone of the RP occur. During the second phase, lasting from 50 to 60 ms, depending on the parameters of the stimulus, due to the interaction of excitatory and inhibitory processes, the narrowing of the zone of summation of the RP occurs. During the third phase of perestroika, the zones of RP summation expand and their functional disorganization occurs. Neural structures return to their initial state and become ready for the perception of a new stimulus [7]. Since the second phase of the formation of RP neuron ends in 60-70 ms after the presentation of the light stimulus, the duration of the light pulses is taken equal to 50 ms. During this time, excitatory and inhibitory processes in the RP of neurons will be formed.

The disappearance of RP neurons occurs in the period from 100 to 200 ms after the presentation of the light stimulus [8]. Therefore, two light pulses will be felt separate if the second light pulse is presented 100-200 ms after the start of the presentation of the first light pulse. Then the total duration of the light pulse and the interpulse interval should be τ _imp + t _mission ≥ ≥ (100 ... 200) ms.

With the duration of the light pulse τ _imp = 50 ms, the initial duration of the interimpulse interval should be t _nmii ≥ (50 ... 150) ms and taken equal to 150 ms.

The perception of a visual stimulus is hampered under the conditions of reverse masking, which consists in a deterioration in the perception of the first time stimulus due to the presentation of the second stimulus in the immediate spatial and temporal proximity to the first. It was shown that there is not only a reverse effect, but also direct masking, in which the first stimulus affects the quality of perception of the second [9]. With an interstimulus interval of 500 ms, masking effects are absent or weakly expressed [10]. To eliminate the masking effect in the first or third stages of measurements, the sequence of paired light pulses is repeated after a constant time interval of 1 s.

To determine lability as the maximum frequency of reactions to rhythmic stimuli, it is necessary to use not paired light pulses repeated over a constant time interval, but a rhythmic sequence of light pulses. The sum of the duration of the light pulse τ _imp and the duration of the critical interpulse interval t _cr between rhythmic light pulses, at which a subjective sensation of fusion of light pulses is achieved, determines the value of the period above which the visual system can sense rhythmic light pulses in exact accordance with their rhythm.

Moreover, for the lability of the visual system of a person, the repetition rate of light pulses in Hz is taken:

F = 1 / (τ _imp + t _cr ),

where F is the lability of the human visual system;

τ _imp - the duration of the light pulse in seconds;

t _cr - the critical duration of the inter-pulse interval between light pulses in seconds.

Thus, the inventive method for determining the lability of the human visual system has new properties that determine the receipt of a positive effect.

Example. Subject Z., 20 years old, using a personal computer that emits light flickers through the LPT port on the indicator of the test panel of the subject, showed a sequence of paired light pulses of duration τ _imp equal to 50 ms separated by an initial interpulse interval of duration

t _Nmii equal to 150 ms, repeating through a constant time interval T equal to 1 s (figure 1; figure 3, the time interval 0-T ₁ ).

In the process of measurement through the LPT port, the signals from the buttons "Decrease fast", "Increase slow", "Decrease discrete" and "Measurement" were sent to the personal computer from the test subject's remote control.

In the presence of a signal from the “Decrease fast” button, the computer reduced the duration of the inter-pulse interval between light pulses paired with a speed of V ₁ equal to 20 ms / s, with a signal from the “Increase slow” button increased with a speed of V ₂ equal to 2 ms / s , in the presence of a signal from the "Decrease Discrete" button, it was reduced discretely in 0.1 ms increments, in the presence of a signal from the "Measurement" button, the duration of the inter-pulse interval between light pulses was recorded, the lability of the visual system was calculated, the value of the laby nosti on the monitor screen displays the results of measurements in the file and produce a predetermined sequence of light pulses.

At the first stage, the test subject, giving a signal from the "Decrease fast" button (Fig. 3, time interval T ₁ -T ₂ ), determined the moment of subjective merging of two light pulses in a pair into one (Fig. 3, time moment T ₂ ).

At the second stage, the test subject, giving a signal from the "Slow Increase" button (Fig. 3, time interval T ₃ -T ₄ ), determined the moment of subjective sensation of the separation of two light pulses in a pair (Fig. 3, time moment T ₄ ).

At the third stage, the test subject, giving a signal from the "Discrete Decrease" button (Fig. 3, the time interval T ₅ -T ₆ ), determined the moment of subjective merging of two light pulses in a pair into one and gave a signal from the "Measurement" button (Fig. 3 , time T ₆ ).

The computer recorded the duration of the threshold interpulse interval t _then between light pulses in a pair.

At the fourth stage of measurements, the subject was presented with a rhythmic sequence of light pulses of duration τ _imp equal to 50 ms, separated by a threshold inter-pulse interval t _then (Fig. 2; Fig. 3, time interval T ₆ -T ₇ ).

Then the subject, giving a signal from the "Discrete Decrease" button (Fig. 3, time interval T ₇ -T ₈ ), determined the moment of subjective fusion of light pulses (Fig. 3, time point T ₈ ), then sent a signal from the "Measurement" button (Fig. 3, point in time T ₉ ).

The computer recorded the duration of the critical interpulse interval t _cr between light pulses in a pair equal to 0.0017 seconds, calculated the value of the lability of the human visual system by the formula:

F = 1 / (τ _imp + t _cr ) = 19.34 Hz,

where F is the lability of the human visual system;

τ _imp - the duration of the light pulse in seconds;

t _cr - the critical duration of the inter-pulse interval between light pulses in seconds.

Next, the computer deduced the value of the lability of the human visual system on the monitor screen, entered the measurement result in the archive and presented the initial sequence of paired light pulses.

In accordance with the recommendations of physiologists, the subject performed a series of 10 measurements. As a result of the measurements, the following values of the lability of the subject's visual system in Hz were obtained: 19.34; 19.32; 19.27; 19.30; 19.32; 19.34; 19.36; 19.31; 19.34; 19.39. The arithmetic mean of the measured values of the lability of the visual system is 19.33 Hz, the standard deviation is 0.033 Hz, the confidence limits of the random component of the error of the measurement result with a confidence probability of 0.95, taking into account the student coefficient, 0.074 Hz.

As a result of a series of 10 measurements to assess the lability of the human visual system, performed by the subject in a known manner [3], the following lability values were obtained in Hz: 15.02; 15.07; 15.01; 15.00; 15.03; 15.08; 15.05; 15.11; 15.07; 15.05. The arithmetic mean of the measured values of the lability of the visual system is 15.05, the standard deviation is 0.034 Hz, the confidence limits of the random component of the error of the measurement result with a confidence probability of 0.95, taking into account the student coefficient, 0.074 Hz.

Thus, the proposed method for determining the lability of the human visual system can improve the reliability of the assessment of lability. The proposed assessment corresponds to the accepted measure of lability as the maximum frequency of reactions that the organ (visual system) can reproduce in exact accordance with the rhythm of the applied stimuli, that is, with their rhythmic presentation.

Information sources

1. Makarenko N.V. The critical frequency of light flickering and alteration of motor skills // Human Physiology. - 1995. - T. 21, No. 3. - S.13-17.

2. Rozhentsov VV Measurement of differential sensitivity of vision to the frequency of light flickers // Design and technology of electronic means. - 2005. - No. 2. - S.50-53.

3. RF patent 2251959, IPC АВВ 3/10. A method for determining the lability of the human visual system / V.V. Rozhentsov, M.T.Aliyev, A.G. Maslennikov, I.V. Petukhov (RF). - Publ. 05/20/2005, Bull. No. 14.

4. Vvedensky N.E. Excitation, inhibition and anesthesia / I.M.Sechenov, I.P. Pavlov, N.E. Vvedensky. Selected Works. T.2. Physiology of the nervous system. M .: Nauka, 1952. - 602 p.

5. Kravkov S.V. Eye and his work. Psychophysiology of vision, lighting hygiene. -

4th ed., Rev. and add. - M.-L.: Publishing House of the Academy of Sciences of the USSR, 1950 .-- 531 p.

6. Semenovskaya E.N. Electrophysiological studies in ophthalmology. - M .: Medgiz, 1963 .-- 279 p.

7. Podvigin N.F. Dynamic properties of neural structures of the visual system. L .: Science. 1979. - 158 p.

8. Shevelev I.A. Temporary signal processing in the visual cortex // Human Physiology. - 1997. - T.23, No. 2. - S.68-79.

9. Kropotov Yu.D., Ponomarev V.A. The reaction of neurons and evoked potentials in the subcortical structures of the brain during visual recognition. Message IV. The effect of masking visual stimuli // Human physiology. - 1987. - T.13, No. 4. - S. 561.

10. Taroyan N.A., Myamlin V.V., Genkina O.A. Interhemispheric functional relations in the process of solving a visual-spatial problem by a person // Human Physiology. - 1992. - T.18, No. 2 - S.5-14.

Claims (1)

The method for determining the lability of the human visual system by presenting a test subject with a sequence of paired light pulses of duration 50 ms, separated by an interpulse interval of 150 ms, repeated through a constant time interval of 1 s, at the first stage of measurements, the duration of the interimpulse interval between light pulses in a pair is reduced with a constant 20 ms / s, until the subject determines the moment of subjective fusion of two light pulses in a pair into one, at the second stage of measurements the inter-pulse interval between light pulses in a pair is increased at a constant speed of 2 ms / s, until the subject determines the moment of subjective sensation of the separation of two light pulses in a pair, at the third stage of measurement, the duration of the inter-pulse interval between light pulses in a pair is discretely reduced in increments of 0.1 ms, until the subject determines the moment of subjective fusion of two light pulses in a pair into one, the duration of the inter-pulse interval between light pulses in a pair at a given time take the threshold duration of the inter-pulse interval t _then , characterized in that at the fourth stage of the measurements, the subject is presented with a rhythmic sequence of light pulses of the same duration equal to 50 ms, separated by a threshold inter-pulse interval of t _then , then the duration of the inter-pulse interval between rhythmic light pulses is reduced discretely with a step 0.1 ms, until the subject determines the moment of subjective fusion of light pulses, the duration of the inter-pulse interval between rhythmic light pulses at a given time are taken as the critical duration of the inter-pulse interval t _cr , the lability of the human visual system is taken equal to the value of the repetition rate of rhythmic light pulses, Hz:
F = 1 / (τ _imp + t _cr ),
where F is the lability of the human visual system, τ _imp is the duration of the light pulse, s; t _cr - the critical duration of the inter-pulse interval between light pulses, s, determined at the fourth stage of measurement.

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