RU2286082C1 - Device for determining lability of human visual system - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: device has remote control panel, point light source, counter, indication unit, second pulse oscillator, millisecond pulse oscillator, first univibrator, second univibrator with controlled pulse duration, third univibrator, OR gate and AND gate. First output of AND gate is connected with output of millisecond pulse oscillator; output of AND gate is connected with first input of counter. First output of remote control panel is connected with first input of point light source. Second output of remote control panel is connected with second input of indication unit and the third output is connected with second input of second univibrator having controlled pulse duration. Output of second pulse oscillator is connected with first input of first univibrator. Output of first univibrator is connected with first input of OR gate and with first input of second univibrator having controlled pulse duration. Output of second univibrator is connected with second input of OR gate. Output of OR gate is connected with second input of point light source. Device also has fourth univibrator, flip-flop, reverse value calculator, digital comparator, first and second registers and indicator. First and third univibrators are made with controlled pulse duration. Control board has doubled potentiometer for adjusting pulse duration at outputs of first and third univibrators.

EFFECT: improved truth of research.

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Description

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

The measure of lability according to N.E. Vvedensky is the maximum frequency of reactions that tissue can reproduce in exact accordance with the rhythm of the applied stimuli [1]. The lability value is determined by the critical fusion frequency of flickering phosphene [2], the critical flicker frequency [3, 4] and the critical frequency of sound clicks [5].

The well-known device is "Fosphen" - an electronic digital device for studying the lability of nervous processes at the critical fusion frequency of flickering phosphene, the critical frequency of light flicker and the critical frequency of sound clicks [5].

Known neurochronometer [5], DPPI apparatus [6] and IRIS device [7] for studying the properties of the nervous system, including lability at the critical frequency of light flicker.

A disadvantage of the known technical means is an unreliable determination of the true value of lability, since during rhythmic stimulation, the continuous activation of a neuron, which is a structural-morphological functional unit of the brain [8], is observed only at frequencies of no more than 13-15 Hz [9].

Closest to the technical nature of the present invention is a device for determining the lability of the human visual system, containing a control panel and a point source of light [10].

The disadvantage of this device is the low accuracy of determining the moment of merging of light pulses.

The inventive device allows to increase the reliability of the study due to a more accurate determination of the moment of fusion of light pulses.

It was experimentally established that the time of perception of visual information t _take depends on the duration of the light pulse τ _imp and the function t _take = f (τ _imp ) has a minimum. Lability at the minimum point is calculated by the formula [11]

,

,

therefore, the function F = f (τ _imp ) has a maximum.

In the present invention, a device for studying the inertia parameters of the human visual system, comprising a control panel, a point light source, a counter, an indication unit, a second pulse generator, a millisecond pulse generator, a first one-shot, a second one-shot with an adjustable pulse width, a third one-shot, an OR element and element And, the first input of which is connected to the output of the millisecond pulse generator, and the output to the first input of the counter, the first output of the control panel is connected to the first input of a point light source, the second output with the second input of the display unit, the third output with the second input of the second one-shot with an adjustable pulse duration, the output of the second pulse generator is connected to the first input of the first one-shot, the output of which is connected to the first input of the OR element and to the first the input of the second one-shot with an adjustable pulse duration, the output of which is connected to the first input of the third one-shot, the output of which is connected to the second input of the OR element, the output of which is connected to the second input of a point light source, additionally introduced the fourth one-shot, trigger, reciprocal calculator, digital comparator, first and second registers and an indicator, the fourth output of the control panel connected to the second inputs of the first and third one-shots, the input of the fourth one-shot connected to the output of the second pulse generator and the output is with the second input of the counter and with the first input of the trigger, the output of which is connected to the second input of the And element, the output of the third one-shot is also connected to the second input a trigger house with a second input of a reciprocal calculator, the first input of which is connected to the output of the counter, and the output - with the first input of the digital comparator and the first input of the first register, the output of which is connected to the first input of the second register and the second input of the digital comparator, the first output which is connected to the second input of the first register, and the second output to the indicator input and to the second input of the second register, the output of which is connected to the first input of the display unit, the first and third one-shots are made with adjustable uemoy pulse duration, and the control unit further comprises a double potentiometer for adjusting the pulse width at the outputs of the first and third monostable multivibrators.

The inventive device due to the introduction of the fourth one-shot, trigger, inverse calculator, digital comparator, first and second registers and indicator allows you to determine the lability of the human visual system at the maximum point of the function F = f (τ _imp ).

Thus, the claimed device differs from the known new property, which determines the receipt of a positive effect.

Figure 1 presents the structural diagram of the inventive device, figure 2 is a timing diagram explaining its operation.

Figure 3 presents a timing diagram of a sequence of paired light pulses presented to determine the lability of the human visual system, where:

- τ _imp - the duration of the light pulse;

- t _NMI - the initial duration of the _inter -pulse interval;

- T is the time interval for the repetition of a sequence of paired light pulses.

Figure 4 presents the timing diagrams of two light pulses separated by an initial interpulse interval t _nmii and the visual sensations caused by them, where:

- figa is a timing diagram of two light pulses separated by an initial interpulse interval t _nm , causing a visual sensation of separation of pulses;

- figb - time diagram of the visual sensation of the two light pulses shown in figa;

- figv 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;

- Fig. 4 g is a temporal diagram of the visual sensation of two light pulses shown in Fig. 4c;

- τ ₁ - the time of visual sensation is the time between the moment of exposure of light to the retina and the moment of occurrence of the corresponding visual sensation [1, 2] (fig.4b);

- τ ₂ is the recovery time is the time between the moment of termination of the effect of light on the retina and the moment the corresponding visual sensation disappears [1, 2] (Fig. 4b).

The inventive device contains a generator of 1 second pulses, a generator of 2 millisecond pulses, the first 3, second 4 and third 5 single vibrators with adjustable pulse duration, the fourth 6 single vibrator, element 7 AND, element 8 OR, counter 9, trigger 10, calculator 11 reciprocal, a digital comparator 12, the first 13 and second 14 registers, a point source of light 15, an indicator 16, an indication unit 17 and a control panel 18.

The generator of 1 second pulses is designed to generate pulses with a frequency of 1 Hz, providing a given repetition time of a sequence of paired light pulses, and can be performed according to the known scheme.

The generator of 2 millisecond pulses is designed to generate a sequence of counting pulses with a frequency of 1 kHz, providing a measurement accuracy of 1 ms, and can be performed according to the known scheme.

Single vibrators 3.5 are designed to generate light pulses lasting from 2 to 50 ms, single vibrator 4 is designed to form an adjustable pause between two light pulses in the range from 3 to 150 ms. The one-shot 6 is designed to generate a short pulse to reset the counter 9 and to set the trigger 10 to "1".

Single vibrators 3-6 can be performed using the K555AG1 microcircuit, which can be triggered both on the leading and trailing edges of the incoming pulses [12, Fig.3.32, p.116].

The counter 9 is designed to determine the total duration of the light pulse τ _imp and the threshold interpulse interval t _then between the light pulses in a pair, recorded at the time of the subjective merger of two light pulses in a pair into one, with an accuracy of 1 ms.

Trigger 10 is a standard RS trigger.

The reciprocal of the calculator 11 can be performed according to AS 1173412 [13].

The digital comparator 12 is designed to determine the lability of the visual system at the maximum point of the function F = f (τ _imp ) and can be performed using the K555SP1 microcircuit according to the scheme [14, Fig. 141, p.112].

Register 13 is used to store the current lability value, and register 14 is used to fix the lability of the visual system at the maximum point of the function F = t (τ _imp ). Registers 13 and 14 can be performed on chips K555IR22.

The point light source 15 is intended for the presentation of light pulses and can be performed on a LED type AL307EM.

The indicator 16 is intended to indicate the moment of fixing the value of the lability of the visual system at the maximum point of the function F = f (τ _imp ) and can be performed on an AL307BM type LED.

The indicators in the display unit 17 are intended to display the lability of the visual system at the maximum point of the function F = f (τ _imp ) and can be performed on indicators of the ALS333A type.

The remaining functional units of the structural diagram of the device are well known.

The device operates as follows. The test subject sets the potentiometer knob of the control panel 18 to its initial position, corresponding to the pulse duration at the output of the second 4 single vibrator, equal to the initial duration of the interpulse interval t _nm = 150 ms, and the dual potentiometer knob to the position corresponding to the pulse duration at the outputs of the first 3 and third 5 single vibrators τ _imp = 2 ms. When the power is turned on, the counter 9, trigger 10, the output register of the calculator 11, the first 13 and second 14 registers are reset (chains are not shown). From the control panel 18, power is supplied to a point light source 15, the generator 1 generates pulses with a frequency of 1 Hz (Fig. 2a), which are fed to the input of the first 3 single-shot, which generates a pulse of a given duration of 2 ms along the leading edge of each pulse (Fig. 2b) and the generator 2 generates a sequence of counting pulses arriving at the first input of the element 7 And (fig.2z).

Simultaneously, the pulses from the generator 1 are fed to the fourth 6 single-shot, which generates a short pulse along the leading edge of each pulse (Fig.2c), which resets the counter 9 and sets the trigger 10 to "1" (Fig.2g). From the output of the trigger 10, the level of the logical unit goes to the second input of the element 7 AND, while the pulses from the output of the generator 2 through the element 7 And go to the first input of the counter 9.

The pulse from the output of the first 3 single vibrator through the element 8 OR is supplied to a point source 15 of light (Fig.2E) and the trailing edge starts the second 4 single vibrator. On the trailing edge of the pulse from the output of the second 4 one-shot, the third 5 one-shot is launched, generating a pulse of a given duration of 2 ms (fig.2d), which through the element 8 OR enters the point source 15 of the light (fig.2e).

On the front of the pulse from the output of the third 5 one-shot trigger 10 is reset and its output is set to a logic zero level (Fig.2g), which is fed to the second input of element 7 And, while the passage of pulses from the output of generator 2 through element 7 And to the first input of the counter 9 is blocked.

At the output of element 7 And a packet of pulses will be formed (Fig. 2i), the number of pulses in the packet is equal to the pulse duration at the output of trigger 10 (Fig. 2g), equal to the sum of the pulse durations at the outputs of the first 3 and second 4 single-vibrators in ms. The number of pulses in the packet is considered to be counter 9, the counting result is recorded by the pulse from the output of the third 5 single-vibrator to the calculator 11. The calculation result is transmitted to the first input of the first 13 registers and to the first input (input A) of the comparator 12. The number at the input A of the comparator 12 is greater than the number by its second input (input B), as register 13 is reset. Therefore, at the first output (output A> B) of the comparator 12, a logical unit level is formed, according to which the result of the calculation from the output of the calculator 11 is recorded in the first 13 register, from the output of which goes to the second input (input B) of the comparator 12. Since the numbers at the inputs A and B of the comparator are equal, at the first output (output A> B) of the comparator 12, a logic zero level is formed.

Tested by rotating the handle of the potentiometer, the control panel 18 reduces the pulse duration at the output of the second 4 single-vibrator (Fig. 2 g) until the moment of subjective merging of two light pulses in a pair into one. The reciprocal of the sum of the pulse durations at the outputs of the first 3 and second 4 single vibrators is taken as the lability of the human visual system with a pulse duration of τ _imp = 2 ms and is calculated in calculator 11 by the formula

F = 1 / (τ _imp + t _then ),

where F is the lability of the human visual system, kHz; τ _imp - the duration of the light pulse, ms; t _then - the duration of the interpulse interval at which the subject has a feeling of subjective fusion of two light pulses in a pair of one, ms.

The test subject sets the potentiometer knob of the control panel 18 to its initial position, and by rotating the handle of the double potentiometer of the control panel 18 increases the pulse duration τ _imp at the outputs of the first 3 and third 5 single-vibrators by 2 ms, then the process of calculating the lability F is repeated in the same way.

The specified sequence of actions is repeated until the result of calculating the next lability value at the input A of the comparator 12 is less than the previous lability value recorded in the first 13 register and fed to the input B of the comparator 12. At the first output (output A> B) comparator 12, the logic zero level will be saved, and at the second output (output A <B) a logical unit level will be formed, according to which the result of the previous calculation from the output of the first 13 register will be recorded in the second 14 register and light I am indicator 16, indicating that the lability of the human visual system at the maximum point of the function F = t (τ _imp ) is determined.

To read this lability value, the subject switches the key on the control panel 18, removes power from the point light source 15 and supplies it to the display unit 17, which displays the lability value in kHz.

The lability of the human visual system is explained by its inertia, that is, the presence of visual sensation time τ ₁ and recovery time τ ₂ (figure 4).

Upon presentation to the subject of two light pulses of duration τ _imp > τ ₁ separated by an initial interpulse interval t _nm > t _then (Fig. 4a), he experiences a subjective sensation of separation of the two light pulses (Fig. 4b). With a decrease in the duration of the _inter -pulse interval t _nm between two light pulses to a value of m _mission = t _then (Fig. 4c), the subject experiences a sensation of subjective fusion of two light pulses in a pair into one (Fig. 4d). The sum of the duration of the light pulse τ _imp and the duration of the threshold interpulse interval t _then between two light pulses, at which the subjective sensation of the fusion of two light pulses in a pair is achieved, determines the threshold value of the period above which the visual system can sense light pulses in exact accordance with their frequency.

During the action of a light stimulus, receptive fields (RP) of neurons undergo three phases of restructuring [15]. 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, the process of narrowing the zone of summation of the RP proceeds. During the third phase of perestroika, the zones of summation of fields expand and the functional disorganization of RP. Neural structures come to their original state and become ready for a new cycle of perception.

The disappearance of RP neurons occurs in the period from 100 to 200 ms after the presentation of the light stimulus [16]. 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.

It was experimentally established that, with a light pulse duration τ _imp = 2 ms, the duration of the threshold inter-pulse interval t _pores is in the range from 38 to 106 ms, with a duration τ _imp = 50 ms, from 8 to 66 ms, the maximum lability value corresponds to the duration of the light pulse τ _imp from 5 to 30 ms.

Therefore, the initial duration of the inter-pulse interval at a pulse duration of τ _imp = 2 ms should be

t _NMI ≥ (38 ... 106) ms,

when the pulse duration τ _imp = 50 ms it should be

t _NMI ≥ (8 ... 66) 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 spatiotemporal 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 [17]. With an interstimulus interval of 500 ms, masking effects are absent or weakly expressed [18]. To eliminate the masking effect, the sequence of paired light pulses is repeated at a constant time interval of 1 s.

Thus, the claimed device allows you to determine the value of the lability of the visual system of a person at the maximum point of the function F = f (τ _imp ).

Information sources

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Claims (1)

A device for determining the lability of the human visual system, containing a control panel and a point light source, characterized in that it is equipped with a counter, an indication unit, a second pulse generator, a millisecond pulse generator, a first one-shot, a second one-shot with an adjustable pulse duration, a third and fourth one-shots, OR element, AND element, trigger, reciprocal calculator, digital comparator, first and second registers and indicator, while the first electronic input And And connected to the output of the millisecond pulse generator, and the output to the first input of the counter, the first output of the control panel connected to the first input of a point light source, the second output to the second input of the display unit, the third output to the second input of the second one-shot with an adjustable pulse duration , the output of the second pulse generator is connected to the first input of the first one-shot, the output of which is connected to the first input of the OR element and to the first input of the second one-shot with an adjustable pulse duration, the output of which is connected to the first input of the third one-shot, the output of which is connected to the second input of the OR element, the output of which is connected to the second input of a point light source, the fourth output of the control panel is connected to the second inputs of the first and third one-shots, the input of the fourth one-shot is connected to the output of the second pulse generator and the output is with the second input of the counter and with the first input of the trigger, the output of which is connected to the second input of the And element, the output of the third one-shot is also connected to the second input of the trigger and with the second input of the reciprocal calculator, the first input of which is connected to the output of the counter, and the output is the first input of the digital comparator and the first input of the first register, the output of which is connected to the first input of the second register and the second input of the digital comparator, the first output of which connected to the second input of the first register, and the second output to the indicator input and the second input of the second register, the output is connected to the first input of the display unit, the first and third one-shots are made with adjustable impulse duration bca and control unit comprises a double potentiometer for adjusting the pulse width at the outputs of the first and third monostable multivibrators.

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