RU2258453C1 - Method for detecting the degree of cerebral interhemispheric asymmetry - Google Patents

Abstract

FIELD: medicine, psychophysiology.

SUBSTANCE: as a value for cerebral functional state one should apply the level of functional capacities of central nervous system (LFC CNS). Senso-motor test should be performed unimanually at a pause of about 7 min, not less. Coefficient of interhemispheric asymmetry should be calculated by the following formula: Cas = (LFCl - LFCr)/(LFCl + LFCr)*100%, where LFCl - the level of functional capacities of nervous system at performing senso-motor test with one's right hand; LFCr - the level of functional capacities at performing senso-motor test with one's left hand. The innovation enables to apply integral value depicting cerebral functional state.

EFFECT: higher significance of testing.

1 dwg, 3 ex, 1 tbl

Description

The invention relates to the field of psychophysiology for diagnosing a functional state of a person and evaluating interhemispheric asymmetry.

As a rule, interhemispheric asymmetry is estimated either qualitatively by sensory and motor asymmetries (Leutin VP, Nikolaeva EI Psycho-physiological adaptation mechanisms and functional asymmetry of the brain. Novosibirsk: Nauka, 1988, 192 pp.), Or quantitatively by the time of the sensorimotor reaction in response to auditory or visual stimuli (N.D. Ovchinnikov, Methods for the quantitative assessment of interhemispheric functional asymmetry of the brain // Human Physiology. 1997. V.23. No. 6. P.131-132. Moroz MP, Udalova G.P., Zakharov A.V. Interhemispheric asymmetry p with changes in the functional state of a person. // Human Physiology. 1986. T. 12. No. 2. S.179-186.).

The cited examples of questionnaires in the first source (Leutin V.P., Nikolaeva E.I., 1988) indicate that they are directed to the subjective self-esteem of the subjects, which is not always true, and conducting samples that gives more visual information is always very laborious because of their abundance, which is caused by lack of trust in them.

A quantitative assessment of the degree of asymmetry is more informative. However, to determine the functional asymmetry of the brain by the critical fusion frequency of light flickers (Ovchinnikov ND, 1997), a specially designed device is required.

Closest to the proposed method is a method for calculating the interhemispheric asymmetry index using the average response time for a bimanual sensory-motor reaction to a light stimulus supplied to the center of the field of view (Moroz M.P., Udalova G.P., Zakharov A.V., 1986). In this case, the subject responds to the appearance of visual stimuli by pressing the corresponding buttons on the remote control simultaneously with the thumbs of the left and right hands. A total of 50 visual stimuli are supplied.

The hemisphere asymmetry coefficient (CAS) is calculated by the formula:

Cas = (D-S) / (D + S) 100%,

where D and S are the average response time with the right and left hand, respectively.

But, as shown by the authors themselves, the average response time is an uninformative indicator. This is the disadvantage of the proposed method. The authors indicate that a more informative indicator of the functional state of the nervous system is such an indicator as the central nervous system UVB (level of functional capabilities of the central nervous system), proposed by T.D. Loskutova (Moroz M.P., Udalova G.P., Zakharov A.V., 1986) and calculated based on the variational analysis of latent periods of the visual-motor reaction.

However, they themselves do not use it to calculate the degree of interhemispheric asymmetry.

The proposed formula for calculating the UVB of the central nervous system was derived empirically by Loskutova on the basis of parallel studies of the bioelectrical activity of the brain and was widely used in the examination of disability and really reflects the functional state of the central nervous system (Loskutova T.D. Response time as a psychophysiological method for assessing the functional state of the central nervous system. // Neurophysiological studies in the examination of disability. -L.: Medicine, 1973.-S68-84). However, in these studies, this sensorimotor test was always performed for only one arm and was not used to assess interhemispheric asymmetry.

The technical result of the invention is to increase the information content of the asymmetry index.

The technical result is achieved by the fact that in the method for determining the degree of interhemispheric asymmetry of the brain, including calculating the coefficient of interhemispheric asymmetry, it is new that, as an indicator of the functional state of the cerebral hemispheres, the level of functional capabilities of the central nervous system (CNS CNV) is used when performing right and left hand touch -motor test, which is carried out unanimally with a pause of at least 7 minutes, and the coefficient of interhemispheric asymmetry is calculated as follows:

CAS = (UVVL-UVVp) / (UVVL + UVVp) · 100%,

where UVVl is the level of functional capabilities of the nervous system when performing the sensorimotor test with the right hand, which reflects to a greater extent the activity of the left hemisphere, since the final stage - the motor reaction of the right hand - is carried out under the control of the motor zones of the left hemisphere;

UVVp is the level of functionality when performing the sensorimotor test with the left hand, which reflects to a greater extent the activity of the right hemisphere, since the final stage - the motor reaction of the left hand - is carried out under the control of the motor zones of the right hemisphere.

A positive value for Cas indicates the dominance of the left hemisphere, a negative value indicates dominance of the right.

The proposed method differs from the known one in that it is not the average reaction time per 50 visual signals that is used for calculating the Cas, but the UVB calculated for each hemisphere, which is much more informative. In addition, a computerized version of the technique of T.D. Patchwork. Also from the known method, where the authors used a bimanual test, the proposed method differs in that the sensorimotor reaction is carried out unanimally with the index finger, that is, in turn, first with one, then with the other hand, with a pause of 7-10 minutes to eliminate fatigue. Such motivation for the unimanual execution of the test ensures the selective activation of predominantly one hemisphere at the time of the motor reaction. The test itself takes about 7 minutes and in this case, the duration of rest is equal to or slightly longer than the duration of the test. The duration of rest in our test is equal to or slightly longer than the duration of the test itself. We analyzed the percentage of subjects in whom, at the end of the test, the response time increased (+ BP) or shortened (-BP) .Longer response time to the end of the test indicates fatigue. The first and second test, conducted after a pause of 7-10 minutes, was compared according to these indicators. The results are shown in the table.

Table 1
Changing the response time during a visual motor test in adults 40-48 years old and children 9-10 years old. Group The total number of subjects Test one. + BP,% Test one. -VR,% The second test. + BP,% The second test. -VR,% Adults 60 51.7 48.3 53.3 46.7 Children 57 52.6 47.4 56.1 43.9

Both in the first and second tests in the sequence, with a pause between them of 7-10 minutes, the number of such subjects in whom the response time increased increased from 56.1 to 51.7%. This does not significantly differ from the number of subjects (48.3-43.9%), in whom the response time improves (p> 0.05). There are also no significant differences in these indicators in adults and children. (Terentyev P.V., Rostova N.S. Workshop on Biometrics.-L., LSU, 1977. P.48, P.130).

Thus, this method meets the criteria of "novelty" and "inventive step".

The subject is seated at a distance of 35 cm from the monitor screen, in the center of which a visual stimulus appears (red circle with a diameter of 2 cm on a blue background). Intersignal intervals vary from 1 to 4 seconds. A total of 50 stimuli are supplied.

The subject is instructed to respond as quickly as possible by pressing the index finger on the key when a visual stimulus appears. The key is located on the right when it reacts with the right hand, and on the left when it reacts with the left. After the test with one hand, a pause is mandatory to avoid fatigue. On average, the test for each hand lasts from 5 to 10 minutes, which depends on the age of the subject.

Before starting the test, the test subject is required to conduct a training test to familiarize himself with the method, where the number of signals is 4-5 stimuli. Then, according to the latent periods of the reactions, the curve of the variational distribution is constructed using the formula proposed by T.D. Patchwork, calculated CNF UVV for the left and right hemisphere, respectively.

However, in the calculation of UVB, we proposed to omit the logarithm function, since in children at very low, namely negative UVB values, difficulties arise in the calculation of Cas. And we proposed to use the following formula for UVB calculations, omitting the logarithm:

where P _max is the maximum probability corresponding to the limits of the modal class of the variational distribution of latent periods of the visual-motor reaction;

ΔТ _0.5 - reaction time range corresponding to a probability level equal to half the maximum (0.5 Rmax);

T _0.5 - the value of the reaction time corresponding to the middle of this range. The parameters P _max ΔT _0.5 , ΔT _{0.5 are} determined by the curve of the variational distribution (figure 1).

Variational distribution curve

Further, the obtained UVB values are entered in the above formula

for calculating cas. All of the above calculations are computerized.

Examples:

Subject No. 1 (6.5 years): UVVL (right hand) = 0.305. UVBp (left arm) = 1.94.

Cas = (0.305-1.94) / (0.305 + 1.94) 100% = (-1.635 / 2.245) 100% = 73%. A negative sign indicates dominance of the right hemisphere.

Subject No. 2 (22 years old): UVVL (right hand) = 6.0, UVVp (left hand) = 3.9.

Cas = (6.0-3.9) / (6.0 + 3.9) · 100% = (2.1 / 9.9) · 100% = 21.2%.

A positive sign indicates dominance of the left hemisphere.

Subject No. 3 (21 years old): UVVL (right hand) = 5.6. UVVp (left hand) = 4.13.

Cas = (5.6-4.13) / (5.6 + 4.13) 100% = (1.47 / 9.73) 100% = 15.1%.

A positive sign indicates dominance of the left hemisphere.

The advantage of this method is that the UVB index, calculated according to the empirically obtained formula, is an integral indicator reflecting excitability, brain tone, response stability, and therefore, the stability of macro- and microprocesses in the nervous system. While the indicator of the average response time is an uninformative indicator that reflects only the response rate.

Claims (1)

A method for determining the degree of interhemispheric asymmetry of the brain, including the calculation of the coefficient of interhemispheric asymmetry, characterized in that as an indicator of the functional state of the brain, the level of functionality of the central nervous system (CNS CNF) is used when performing a sensorimotor test with the right and left hand, which is performed unanimously with a pause not less than 7 min, and the interhemispheric asymmetry coefficient is calculated by the formula CAS = (UVVL-UVVp) / (UVVL + UVVp) · 100%, where UVVl is the level of functional capabilities of the nervous system when performing the sensorimotor test with the right hand; UVVp - level of functionality when performing a sensorimotor test with the left hand.