A strong nervous system means. The strength of the nervous system in everyday life

The creation of effective and reliable methods for determining the strength of the nervous system made it possible to carry out comprehensive studies of the nature and manifestations of this important parameter of nervous activity. In a number of experimental works carried out in the laboratory of B.M. Teplov, the existence of a complex of various qualities of nervous activity was shown, grouped around the parameter of force and constituting in the aggregate a syndrome of manifestations of this property of the nervous system.
The complexity of manifestations is a necessary formal sign of the properties of the nervous system as a stationary parameter of its organization. “It is impossible to imagine such a basic property of the nervous system, which would have only one manifestation. This will be a particular feature of the nervous system, but by no means its main property ”(B.M. Teplov, 1963, p. 8). As for the strength of the nervous system, the existence around it of such a complex of manifestations and dependencies is now undeniable, and one of the most essential attributes of this property is its inextricable internal connection with the absolute thresholds of sensations.
The now widely known hypothesis of B.M. Teplov about the relationship between sensitivity, reactivity of the nervous system and its strength was first put forward (1955) in the form of a purely theoretical conclusion, derived from the analysis of some statements by I.P. Pavlov about the functional qualities of cortical cells, analysis of the effect of the methods used to increase excitability, as well as some observations by various authors on the behavioral characteristics of animals of a weak type.
B.M. Teplov paid special attention to those statements by I.P. Pavlov, in which he spoke about the causal relationship between the level of “higher reactivity” of the cortical cell and the limit of its performance. IP Pavlov believed that it was the exceptional reactivity and, as a consequence, the rapid functional destructibility of the cells of the cortex that differed from other cells of the nervous system. "Shouldn't the differences between the cortical cells of the weak and strong nervous systems be understood in the same way?" he asks. BM Teplov (1955, p. 6) answers this question positively. Thus, a hypothetical explanation was given for the specific feature of the weak nervous system, which consists in the low limit of its working capacity and the tendency to the rapid development of transcendental inhibition; these qualities were put in connection with the high reactivity, excitability, sensitivity of nerve cells of a weak nervous system.
It must be said that at the moment the hypothesis under discussion was put forward, the concepts of reactivity, excitability and sensitivity were accepted as synonymous, adjacent. Subsequently, however, a need arose for their clarification and a certain distinction, since (in order not to introduce new terms) it is more useful to use each of them to designate, at least in part, a specific range of phenomena. This applies especially to the concept of reactivity in comparison with the other two concepts.
If the concepts of sensitivity and excitability emphasize the content related to the reaction threshold, to the minimum magnitude of the stimulus that causes a state of excitation, then in the concept of reactivity, apparently, the main moment is the magnitude of the reaction itself, on the basis of which the presence of irritation is judged. But by the magnitude of the reaction, it is not possible in all cases to judge the magnitude of the irritation. The intervention of some factors related to both general and individual characteristics of the nervous system can lead to the fact that the reactivity characteristic does not coincide with the sensitivity, excitability characteristic; so, it turns out that a smaller (threshold) signal causes a greater reaction of some autonomic components of the orientation reflex than a superthreshold stimulus (O.S. Vinogradova, E.N. Sokolov, 1955), and it may also turn out that less sensitive the system will be more reactive, i.e. will give a larger response than a more sensitive one (as well as vice versa). It follows that when characterizing the threshold function, it is preferable to use the concepts of sensitivity or excitability than the concept of reactivity.
As for the difference between the concepts of sensitivity and excitability, it is more particular and comes down to the fact that the first concept is usually used in determining the thresholds of sensations and, therefore, is possible only in relation to the function of the organism as a whole, and the second is more used when measuring threshold characteristics of excitable tissues. There is obviously no fundamental difference between the concepts of sensitivity and excitability. In the following, we will mainly use the term "sensitivity" of the nervous system, meaning by this the absolute specific sensitivity of the analyzers (sense organs).
It should be specially emphasized that we are talking about absolute sensitivity, i.e. the reciprocal of the absolute threshold of sensation, and not about the distinctive (discriminative, differential) sensitivity - the reciprocal of the threshold for distinguishing two objects or qualities. We have to say this because sometimes in discussions about the relationship between the strength of the nervous system and sensitivity, the two indicated - completely different - contents of the latter term are mixed, which leads to the loss of the subject of discussion, to inaccurate arguments and to incorrect conclusions.
As for the distinctive sensitivity, the attempts made so far to connect this essential psychophysiological characteristic with the properties of the nervous system, in particular with the alleged “concentrability”, the ability of the nervous process to concentrate, have not led to any clear results (M.N. Borisova, 1959). It is possible that this is due to high exercise capacity, trainability of distinctive thresholds (B.M. Teplov, 1947; M.N. Borisova, 1957), which, therefore, are unlikely to be a function of such stable features of the organization of the nervous system as its main properties .
But let's get back to B.M. Teplov's hypothesis. It was first published in print in 1955. At that time, this exceptionally fruitful "idea really remained only a hypothesis, although it was based on some observations cited by various authors (I.V. Vinogradov, 1933; M.S. Kolesnikov, 1953), indicating increased intensity and extremely difficult extinction of orienting reflexes in dogs of a weak type of nervous system (it is possible, however, that these features of orienting behavior are due not to the sensitivity of the weak type, but to the insufficient dynamism of the inhibitory process in the animals studied).
However, in the 10 years that have passed since that moment, a sufficient amount of data has been accumulated to consider the relationship between absolute sensitivity and the strength of the nervous system as an experimentally established fact. These data were obtained both in the laboratory of B.M. Teplov on humans, and in some other scientific institutions on animals. Let us first present the materials of the works of the first group, and then dwell on the reports of the authors who worked with animals.
Already the initial test of the hypothesis (V.D. Nebylitsyn, 1956, 1959a) gave quite definite results. During this test, the subjects were carried out according to three power methods. One of them is induction, the “caffeine” variant, the other is quenching with reinforcement, the photochemical variant, and the third has not yet been described on the pages of this work. Its essence lies in measuring the shifts in absolute sensitivity under the influence of different doses of caffeine (V.D. Nebylitsyn, 19576). The basis for its more detailed development was some experimental observations on the individual characteristics of the reaction to caffeine in the sense organs. Literature data on this subject are rather contradictory, and besides, there are not very many of them. In this regard, we point out the works of X. Rose and I. Schmidt (N. W. Rose, I. Schmidt, 1947), S. I. Subbotnik (1945), S. A. Brandis (1938), S. V. Kravkov (1939), K-Treme-la and others (K. G. Troemel et al., 1951), who studied the effect of caffeine on visual thresholds, as well as R.I. Levina (1953) and Yu.A. Klaas (1956 ) who studied the effects of caffeine on hearing thresholds.
In none of the works mentioned - except perhaps the work of R.I. Levina - no attempt is made to explain or at least somehow connect the effect of caffeine with the features of higher nervous activity. Meanwhile, the basis for such an attempt could at least be the fact that in the Pavlovian laboratories the caffeine test, using the conditioned reflex method, was ultimately the most reliable and most convenient indicator of the strength of the nervous system.
The technical side of the described technique is very simple. After establishing the background level of sensitivity, the subject received pure caffeine in solution; in the first experiment, the dose was 0.05, in the second - 0.1, in the third - 0.3 g.
After a 20#x2011; minute break, the measurement of thresholds was resumed and continued, depending on the nature of sensitivity changes, for 30–50 min, at intervals of 2 min.
Experiments with the use of caffeine were carried out every other day.
The justification for the validity of this technique was the comparison of its results with data obtained using reference techniques - induction and extinction with reinforcement. Initially (V.D. Nebylitsyn, 1956), the indicator of strength according to this method was the value of sensitivity shifts in the direction of increasing the latter, namely: the absence of changes in sensitivity or its small shifts, lying within 30% of the background, were qualified as a sign of the strength of nerve cells, while large shifts in sensitivity - up to 300% or more of the background - were interpreted as a manifestation of the weakness of nerve cells.
However, as experimental data accumulated, we had to introduce some additions here. The fact is that in some subjects, the intake of caffeine does not cause an increase, but a decrease in sensitivity, sometimes reaching quite significant values, which can be observed both on a visual and on an auditory analyzer. According to the results of comparison with the data of the reference methods, these subjects were recognized as "weak", while at the same time, in the "strong" subjects, there was no decrease in sensitivity after taking caffeine at all.
We could conclude from this that an indicator of the weakness of the nervous system according to this method is either a strong increase in sensitivity, or a decrease in it (regardless of the magnitude of this decrease). In individuals with a strong nervous system, the intake of caffeine either does not cause any change in sensitivity, or causes a relatively small increase in it.
Let us now return to the first experimental work to determine the connection between sensitivity and strength of the nervous system. All 37 subjects had their absolute visual thresholds measured; hearing sensitivity data were obtained from 25 subjects. Unfortunately, not all subjects were tested on each of the three methods for determining the strength of the nervous system. Comparison of data on sensitivity and strength was carried out separately for two analyzers - visual and auditory. In 33 subjects, the strength of the nerve cells of the visual analyzer was determined by at least two experimental methods, and in 11 of them, the strength study was carried out using all three methods.
In the experimental series on the visual analyzer, we met only individual cases of discrepancy between the results of testing the strength of the nervous system by various methods. In 91% of all cases, a coincidence of the results was obtained, which gave us the right to divide all the subjects according to the total assessment of the strength of nerve cells in the visual analyzer into two main groups. One of the groups included 15 people who discovered weakness or a tendency to weakness of nerve cells, the other group included 22 people who showed a greater or lesser level of the actual strength of the nervous system. We were now able to statistically compare the mean absolute sensitivities calculated for both groups. The t criterion turned out to be equal to 7.09, рlt; 0.001, which meant that there was a very clear relationship between the strength of the nervous system and absolute thresholds.
In experiments on the auditory analyzer, two methods were used to determine the strength of nerve cells: one of them was a change in sensitivity under the influence of caffeine, the other was extinction with reinforcement, where a sound stimulus was used as a conditioned stimulus. In 11 subjects, the strength of nerve cells was determined by both methods, in 13 subjects it was determined only by the effect of caffeine on sensitivity, in 1 subject only by extinction with reinforcement.
Comparison of both methods leads us to the conclusion that with their help, basically the same results are obtained. This, in any case, is true for 10 subjects out of 11.
According to the total assessment of the strength of nerve cells, all 25 subjects can be divided into two groups. The average sensitivity of the "strong" group is 96 arb. units, "weak" - 162 conventional units. units Calculation of the criterion t gives its value equal to 3.56 (plt; 0.01).
Thus, the difference in the average sensitivity values ​​for the auditory analyzer is statistically less significant than for the visual analyzer, although it fully satisfies the criteria for a reasonable conclusion. The smaller value of t here owes its origin, in addition to a smaller number of subjects, to two cases of obvious exceptions to the general picture, consisting in a combination of high sensitivity with a high strength of nerve cells. The reason for these exceptions may be the imperfection of the only strength technique with which these subjects were examined (the direct effect of caffeine on sensitivity).
But regardless of this, it should be noted and emphasized that the negative relationship between sensitivity and strength, as follows from experimental materials, is by no means functional (in the mathematical sense of this term). In materials, it is not so rare to find cases of a combination of high sensitivity with high strength of the nervous system and vice versa - low sensitivity with a clear weakness of nerve cells. Obviously, the point here is not reduced to the imperfection of the methods, although, probably, this factor can play a certain role. Rather, one can think about the influence of factors of the functional state of the organism, presumably capable of significantly modifying the nature of the function, especially such a fine one as absolute sensitivity.
There is a number of experimental evidence in favor of the fact that threshold fluctuations occur continuously for both the smallest and very long periods of time (P.P. Lazarev, 1923; K. Kh. Kekcheev, 1946; P. G. Snyakin, 1951 ). Sensitivity does not remain constant even in time intervals measured in seconds and minutes; it varies from one day of experience to the next. We can also assume the existence of slower, but possibly larger shifts in time periods measured in months or even years. The same probably applies to the function of endurance, the working capacity of the nervous tissue, which is the main content of the strength of the nervous system.
All this leads to the fact that the measurement of the closeness of the relationship between two variables, of which one is absolute sensitivity, and the other is the quantified results of the determination of the strength of the nervous system, never gives very high values. Correlation coefficients at best reach only values ​​of the order of 0.7; this, of course, is not at all small, but if we take into account that the factor common to two variables even in this case “responsible” for only about 50% of the variance, it becomes clear how large the share of the total variance is due to the influence of unaccounted for causes.
So, the initial verification of B.M. Teplov’s hypothesis about the relationship between sensitivity and strength confirmed this hypothesis and at the same time showed that the relationship between these two parameters of the nervous system is of a statistical nature, acting by no means in the form of a functional relationship, but in the form of a correlation. In works carried out later with the use of correlation and factor techniques for analyzing the obtained relationships, both the existence of the dependence itself and its statistical nature were repeatedly confirmed.
In the joint work of V.I., Rozhdestvenskaya et al. (1960), devoted to the comparison of all indicators of the strength of the nervous system accepted by that time in the laboratory, indicators of absolute thresholds - visual and auditory - were also included in the comparison. A feature of this work was that 38 out of 40 subjects were carried out according to all methods and, thus, it was possible to calculate the correlation coefficients of each indicator with each other. At the moment, we are interested in correlations between measures of sensitivity and reference indicators of the strength of the nervous system. The latter, if we include the effect of caffeine on sensitivity, were 10. We list them:
1. Extinction with reinforcement of the photochemical conditioned reflex, with visual conditioned stimuli, without caffeine.
2. Extinction with reinforcement of the photochemical conditioned reflex, n "ri visual conditioned stimuli, with the use of caffeine.
3. Induction technique, variant "curve shape".
4. Induction technique, “fatigue” option.
5. Induction technique, "repetition" option.
6. Induction technique, “caffeine” option.
7. Measurement of the effect of caffeine on visual sensitivity.
8. Extinction with reinforcement of the photochemical conditioned reflex, with auditory conditioned stimuli, without caffeine.
9. Same with caffeine.
10. Measurement of the effect of caffeine on auditory sensitivity.
As can be seen from this enumeration, 7 indicators relate to the visual analyzer (1–7), and the remaining three to the auditory analyzer (8–10). The correlation coefficients of the ranks between the reference strength indicators and threshold indicators are given in Table 24, in which the method numbers correspond to the listing just given.
When examining the table, one noteworthy point attracts attention: the correlation coefficients for visual threshold indicators are almost in all cases higher than for auditory ones, and if lower, then by a very small amount; among the first there is not a single insignificant coefficient, among the second there are four of them. We, in fact, have already encountered this difference between the visual analyzer and the auditory analyzer when we noted that the statistical significance of the difference between the average values ​​of the sensitivity of "strong" and "weak" for the visual analyzer turns out to be higher than for the auditory one. Now, with the correlation analysis of the material, this phenomenon is repeated. What are its reasons?
As a hypothetical explanation for some of these reasons, one can point to morphophysiological differences in the organization of the peripheral sensory apparatuses of vision and hearing. If the primary processes of the visual analyzer are from the very beginning of a photochemical and then neuroelectric nature, then in the auditory analyzer the first phase of stimulus energy processing, up to the stimulation of the so-called hair cells, falls on purely mechanical processes. This difference, in general, apparently corresponds to differences in the quality of the physical energies themselves, which serve as adequate stimuli for visual and auditory receptors. It can be assumed that the mechanical properties of the periphery of the auditory analyzer are more susceptible to the influence of various conditions of the organism's existence than the chemical and neurophysiological properties of the retina, especially since the retina is a closed organ, reliably protected by the eyeball, and the cochlea and especially the organs of the middle ear are located in close proximity to external auditory canal. This may be the reason for the high frequency of non-compliance with the rule of communication between sensitivity and strength of nerve cells in the auditory analyzer, leading to the fact that the correlations between auditory sensitivity and force methods for the auditory analyzer are usually lower than between visual sensitivity and strength results. in the visual analyzer.
Table24
Correlation coefficients of ranks between the thresholds of sensations and indicators of the strength of the nervous system (V.I. Rozhdestvenskaya et al., 1960)

Notes. 1) the numbers of methods correspond to the listing given above; 2) plt; 0.05; ** plt; 0.01; ***plt; 0.001.
Another reason for the low correlations of auditory sensitivity indicators especially with the power indicators of the visual analyzer, as well as visual sensitivity with the power in the auditory analyzer, apparently lies in the presence of sometimes serious discrepancies in the level of sensitivity and power between both of these analyzers (see about this Chapter XII ). This factor came out with particular clarity in the work of Z. G. Turovskaya (19636), who, among others, compared in the experiment, on the one hand, some indicators of the strength of the nervous system, and on the other hand, indicators of visual and auditory absolute thresholds. The correlation coefficients obtained by her are given in Table 25, which is an extract from the matrix of intercorrelations presented in this work.
Here is a list of methods for determining the force included in the comparison, in the work of Z. G. Turovskaya:
1. Induction technique, "repetition" option.
2. Induction technique, “fatigue” option.
3. Action on visual sensitivity of distracting sound stimuli.
4. Action on auditory sensitivity of distracting light stimuli.
5. Critical frequency of flickering phosphene (CHF) with a change in the intensity of the electrical stimulus.
The first two of these methods are already known to the reader; the latter will be described in the next chapter. As for the third and fourth methods, we will now briefly describe them. Their justification as methods for testing the strength of the nervous system is given in the works of L.B. Ermolaeva-Tomina (1957, 1959, 1960), as well as in comparisons of these indicators with reference strength methods (V.I. Rozhdestvenskaya et al., 1960; 3 .G.Turovskaya, 1963b). L. B. Ermolaeva-Tomina, unlike some other authors, firstly, discovered the existence of significant individual differences in the direction of shifts in absolute sensitivity under the influence of heteromodal sensory stimulation, and secondly, she found that these shifts are usually opposite in nature during the first and upon subsequent presentation of an additional stimulus.
Table25
Correlation coefficients of ranks between the thresholds of sensations and indicators of the strength of the nervous system (3. G. Turovskaya, 19636)

Notes. 1) a list of power techniques, designated under the numbers \- 5, is given below; 2) plt; 0.05;gt;gt; plt; 0.01.

In ch. 4 we have already dwelled on the individual features of changes in sensitivity at the first presentation of a stimulus - changes that have the character of an orienting reaction and therefore are quite easily extinguished. Recall that these changes were expressed in the "strong" subjects in a decrease, and in the "weak" - in an increase in sensitivity. Continuation of stimulation caused an inversion of the effect of the additional stimulus, regardless of whether it was presented in short portions, only for the time of each threshold measurement, or acted continuously for many minutes. Thus, after extinction of the orienting reaction, which usually occurs very quickly, an additional stimulus causes an increase in absolute sensitivity in persons with a strong nervous system and a decrease in absolute sensitivity in persons with a weak nervous system.
The described dynamics can be illustrated in Fig. 42, which shows for comparison the data of two subjects who differ in the strength of the nervous system. These differences, according to L.B. Ermolaeva-Tomina, are explained from a physiological point of view by the presence of a dominant focus of excitation in “strong” subjects in the analyzer to which the threshold stimulus is addressed, and the absence of such a focus in persons with a weak nervous system, for whom an additional the stimulus acts, therefore, as an external brake. Since these differences were quite definite, the methods investigating the effect of intermittent sound on visual sensitivity and intermittent light on auditory sensitivity were included in the comparison of a number of power methods (V.I. Rozhdestvenskaya et al., 1960), where they showed satisfactory correlations with reference indicators strength of the nervous system. High correlations of these techniques with some variants of the induction technique were also found in the analyzed work of 3.G.Turovskaya (19636). This allows us to consider indicators based on determining the nature of the distracting action of an additional stimulus as fairly reliable indicators of the strength of the nervous system.
But let's get back to Z. G. Turovskaya's data on the connection between force and sensitivity.

Fig.42. The effect of long-acting heteromodal sensory stimulation on the absolute sensitivity of subjects with a strong (A) and weak (B) nervous system.
Solid line - changes in absolute visual sensitivity under the action of sound; dashed line - changes in absolute auditory sensitivity under the action of light. Bi and Bo-sensitivity levels when additional stimulation is turned off.
The abscissa axis is the serial number of sensitivity changes in the experiment; y-axis - sensitivity (in%) relative to the "background" (L.B. Ermolaeva-Tomina, 1959).

As is clear from the list of power techniques used by 3. G. Turovskaya, three of them (1, 2 and 5) definitely relate to the visual analyzer; as for the other two, the exact localization of their sphere of action seems difficult, since they deal simultaneously with two analyzers. This probably explains the fact that the correlations of hearing thresholds with strength indicators, although positive, do not reach the level of significance. At the same time, visual thresholds are highly correlated with indicators of the strength of the nervous system, although not in all cases.
Thus, taking into account the limitations imposed by the modality of stimulation, we can assume that the rule of connection between sensitivity and strength of the nervous system, or more precisely, between visual sensitivity and strength of the nervous system in the visual analyzer, was also confirmed in the work of Z. G. Turovskaya.
Table26
Individual indicators of auditory thresholds in comparison with the results of the EEG of the extinction variant with reinforcement (V.D. Nebylitsyn, 19636)


Subjects


Subjects
Hearing Threshold (in dB from 0.0002 bar)
Preservation of the conditioned response as a result of extinction with reinforcement (in% of the original value)

Sound 70 dB
Sound 90 dB
Sound 70 dB, caffeine 0.2 g
Sound 70 dB
Sound 90 dB
Sound 70 dB, caffeine 0.2 g

R.A.
23
97
94
108
L.B.
7
98
60
115

G.A.
20,5
58
39
76
P.V.
6
27
31
18

K.A.
17,5
73
45
91
M.
5,5
31
13
90

S.A.
14,5
160
100
78
Sh.
5
46
27
140

Sat.
14
70
80
59
G.B.
4
60
78
35

P.A.
14
96
46
40
P.G.
2,5
36
33
66

q.v.
13
54
26
95
G.V.
2
44
53
80

R.B.
12
103
55
93
D.
2
32
64
80

L.A.
11
88
76
92
c.g.
1
39
38
38

R.V.
10,5
52
63
63
Medium
9,7
68,7
56,5
76,4

K.B.
10
82
70
49
Standard deviations
5,93
31,6
24,2
28,1

U.
9
103
52
82

P.B.
8,5
62
102
92




As for auditory sensitivity and strength in the auditory analyzer, confirmation of the initial data on the relationship of these parameters was obtained in work using the EEG variant of extinction with reinforcement (V.D. Nebylitsyn, 19636). Here, three types of extinction with reinforcement were applied: using a normal sound with an intensity of about 70 dB from the average threshold, using a louder (by 20 dB) sound stimulus, and finally using caffeine at a dose of 0.2 g. Individual data for each subject for each of the tests are given in Table 26.
The calculation of the correlation of ranks between auditory thresholds and the first type of extinction with reinforcement gave a value of p = 0.63 (plt; 0.01), which means for individuals with high hearing thresholds a statistically highly significant tendency to maintain the initial value of the conditioned response, and for individuals with low thresholds - the same tendency for the conditioned response to fall as a result of extinction with reinforcement. As we can see, when the sensory modalities of the stimulus used to determine the threshold coincide with the stimulus that serves as a conditioned signal in the extinction test with reinforcement, the connection between sensitivity and strength (actual weakness) is revealed quite clearly. It should be noted, however, that the correlations between hearing thresholds and the other two modifications of reinforcement extinction were much lower: p=0.27 (plt; 0.05) for loud sound and p=0.20 (pgt; gt; 0.05). However, this fact is easily explained. The fact is that with a loud sound stimulus, as already mentioned in the previous chapter, there is an increase in the extinction effect with reinforcement, affecting mainly individuals with a strong nervous system, since in “weak” subjects this effect is in the form of conditional reactions - is achieved already with the usual sound stimulus. This leads to a decrease in the range of individual differences, to the similarity of the end results of extinction with reinforcement of “weak” and “strong” individuals, and, as a consequence, to a decrease in the value of the correlation coefficient. As for caffeine, although its use, although it has, as already mentioned above, an essentially opposite effect - an increase in conditioned reactions, especially in "weak" subjects, ultimately also leads to the elimination of differences between "strong" and "weak" subjects and to the observed decrease in the magnitude of the correlation coefficient. Thus, these two coefficients do not contradict the general picture of rather high correlations between sensitivity and force.
The last (in terms of time) strokes in this picture were made by a collective study by comparing a number of short methods for determining the properties of the nervous system (V.D. Nebylitsyn et al., 1965). Here, absolute visual sensitivity was compared with the EEG variant of extinction with reinforcement, as well as with indicators that will be described in detail in the next chapter: with the determination of HF, with the slope of the reaction time curve as a function of the intensity of the sound stimulus, and with the response time to weak sound stimuli.
The results (Table 27) were paradoxical in a certain sense, since the visual thresholds correlated positively, although significantly only in one case, with the power indicators related to the auditory analyzer, and did not correlate with the previously used CCF method indicator (the sum of the ordinates of the curve), addressed to the visual analyzer. However, the first fact does not contradict the above assumption that the visual thresholds, due to the very nature of the visual analyzer, in fact, from the very beginning, from the receptor apparatus, which is part of the central nervous system, should correlate well enough with any adequate indicators of the strength of the nervous system, regardless of their modalities. The absence of a correlation between the visual thresholds and the sum of the ordinates of the KChF curve, as we believe, is due to moments mainly of a methodological nature. If we ignore this discrepancy, it turns out that in this study, which was characterized by the separate work of experimenters who determine sensitivity and strength, and the absence of mutual information about the results obtained during the work, the existence of a certain relationship between sensitivity indicators and indicators of the strength of the nervous system was revealed.
Reviewing the results of a series of works carried out in the laboratory of psychophysiology, in one form or another experimentally investigating the issue of the relationship between sensitivity and strength, B.M. Teplov notes: “So, now we need to talk not about some hypothesis, but about experimentally proven on a large material ( more than 150 subjects in total) patterns of inverse correlation between the strength of the nervous system and sensitivity ”(1963, p. 24).
Table27
Correlation coefficients between visual thresholds and some indicators of the strength of the nervous system (V.D. Nebylitsyn et al., 1965)
Note. plt; 0.05.
Until recently, experimental facts in support of this regularity were obtained only in humans when determining the threshold of sensation using a speech report. Perhaps this is what gave some polemically minded authors a reason to criticize the hypothesis, regardless of the consistently obtained facts. All the more significant are some facts obtained by various experimenters on animals (dogs) and directly testifying in support of the pattern established in humans.
So, M.V. Bobrova (1960), comparing the characteristics of the rheobase and chronaxy of the muscular apparatus of dogs with their typological features, determined according to the “small standard”, found a completely clear direct relationship between the motor rheobase (by the way, very carefully measured) and the maximum dose of caffeine aged by animals. In other words, a positive correlation was found between the electrical threshold of muscle tissue excitation and the strength of the nervous system, determined by the "classical" method - by the effect of caffeine on reflex activity. The disadvantage of this work is the small number of experimental animals (four) and, consequently, some possibility of random inference.
This shortcoming is devoid of other work carried out on 15 dogs and thus giving quite evidence-based material (D.P. Neumyvaka-Kapustnik, A.I. Plaksin, 1964). Its authors conducted a detailed study of the indicators of the electrical excitability of the neuromuscular apparatus in connection with the typological features of the nervous system, in particular, with its strength. The strength of the nervous system was determined using a caffeine test, daily fasting and super-strong stimuli. Based on these tests, the authors identified 5 dogs of weak and 10 strong types of the nervous system. In all animals, the extensor rheobase of the fingers was measured, and in some dogs, the rheobase of other muscles was also measured.
The data obtained in this work are shown in Table 28, which is an extract (with some processing) from the summary table provided by the authors. Comparison of the values ​​convincingly indicates that the threshold of irritation in animals with a weak nervous system is, on average, much lower than in "strong" animals. Unfortunately, the authors did not use statistical criteria to substantiate the observed relationships, however, the material they cite makes it possible in one case to calculate the correlation coefficient between the strength of the nervous system as a qualitative trait (two groups - “strong” and “weak”) and rheobase as a quantitative series ( the correlation coefficient formula for this case is given by Edwards - P. Edwards, 1960). The value of the coefficient turns out to be equal to 0.625 (рlt; 0.01); this value is about the same order or even higher than the values ​​usually obtained when working with people.
Table28
The average values ​​of the rheobase of the muscular apparatus in dogs of strong and weak types of the nervous system (D.P. Neumyvaka-Kapustnik, A.I. Plaksin, 1964)
Note. The number of experimental animals is indicated in parentheses.

Finally, in confirmation of the connection between sensitivity and strength of the nervous system, one can refer to the data of K.V. type of the nervous system, then in the group of purebred hunting hounds there is an inverse ratio and 71% of dogs belong to the weak type (10 out of 14). As a possible explanation for this fact, the author, referring to the hypothesis of B.M. Teplov, puts forward the assumption that the selection of hunting dogs on the basis of a developed sense of smell leads thereby to the predominance of dogs with a weak nervous system among them. We can probably agree with this, although direct measurements of the threshold of smell were not made by the author.
So, the materials of a whole cycle of experimental work carried out on humans, now substantially supported by a group of facts obtained on animals, indicate the existence of a regular connection between absolute (not distinctive!) sensitivity and the strength of the nervous system. This relationship appears as a positive relationship between the strength of the nervous system and the excitation thresholds of the sensory function: when the contingent of subjects is distributed according to the degree of increase in the strength of nerve cells, the excitation thresholds will also tend to increase (and sensitivity, excitability - to decrease). If this is so, then the ratio between the upper threshold of the reaction of the excitable tissue - the threshold of prohibitive inhibition - and the lower threshold of the reaction - the threshold of excitation (sensation, irritation) - is relatively constant and can be written as where R is the upper and r is the lower threshold reactions.
This expression means that the range between the upper and lower reaction thresholds should ideally remain unchanged from individual to individual, but, of course, certain corrections are made to this ratio in each individual case, due to the influence of factors of a functional order and leading to a distortion of the ratio, and in some cases, possibly nullifying it. That is why we can only talk about the relative constancy of the ratio of the upper and lower thresholds.
Unfortunately, the existing methods for estimating both thresholds do not make it possible to directly compare their values, since the quantitative characteristics of the upper and lower thresholds are given in incommensurable units (the results of an indirect assessment of this ratio are presented in the next chapter). However, repeatedly observed positive correlation coefficients between the reference strength indicators. of the nervous system, each of which gives an approximate estimate of the threshold of transmarginal inhibition, and absolute thresholds that give a measure of sensitivity, clearly indicate that at least a relative, but still constancy of the relationship between the upper and lower thresholds of the function really exists.
It follows that the strength (endurance) of nerve cells and their sensitivity can be considered, in essence, as two sides of a single parameter of the vital activity of the nerve substrate associated with an integral, highly generalized function of response to stimulus intensity. This cardinal property of an excitable tissue includes two inextricably linked poles of the same phenomenon and the sensitivity of the system to irritation at its lowest threshold level, and the endurance of the system in relation to exposure at the level of the limit of its functionality.
The material presented in this chapter allows us to approach the solution of the often discussed question of the biological meaning of the existence of a weak type of nervous system and the reasons for its appearance in the course of the natural evolution of the animal world and man. Opinions of different authors about the advantages and disadvantages of a weak nervous system, about its ability to provide a normal "balance with the environment" are very different. As is known, I.P. Pavlov generally negatively assessed the possibilities of a weak nervous system, calling it "greenhouse", "invalid", etc. The idea of ​​the “inferiority” of the weak type of the nervous system is expressed in the works of S.N. Davidenkov (1947), N.I. Krasnogorsky (1954), B.N. articles by R.E. Kravetsky (1961), N.F. Solodyuk (1961) and others. The number of such examples could be multiplied. However, taking this point of view, it is not easy to explain why the weak type of the nervous system did not die out long ago in the process of natural selection, in competition with the "better adapted" individuals of the strong type. Its existence in the human environment, as well as in the environment of domesticated domestic animals many centuries ago, can still be somehow explained, referring to the absence of biologically determined competition in human society and in the living conditions of domestic animals, although here, too, attempts at explanation meet certain difficulties. But the fact that individuals of a weak type are detected, say, among monkeys that have only recently entered enclosures, or among wild mice and rats that have just been taken for an experiment, is difficult to explain from the “evaluative” position taken by these authors.
Other researchers adhere to a less categorical point of view, assuming that the weak type of the nervous system also has some adaptation mechanisms that ensure proper balance with the environment (D.R. Plecyty, 1957; N.M. Vavilova et al., 1961; S. I. Vovk, 1961). However, the essence of these compensatory or other mechanisms is still not disclosed.
We believe that the concept that connects the weakness of the nervous system with a higher sensitivity allows us to give at least a partial answer to the question of the biological expediency of the existence of a weak type and the mechanisms of its adaptation. It can be assumed that it is the high sensitivity of animals of the weak type of the nervous system, their ability to catch such low-intensity signals that lie below the threshold of perception and, consequently, below the reaction threshold of individuals of the strong type, and is the basis on which their competition with more resilient and, in this sense, indeed “strong” individuals more adapted to life.
Indeed, lower sensory thresholds mean that an earlier orienting response is possible when an enemy or food source approaches. They also mean the possibility of forming conditioned responses to such signal intensities that are not yet perceived by individuals with higher thresholds, and, probably, the possibility of accelerated formation of conditioned connections at physically equal stimulus intensities (due to its greater efficiency for a more sensitive system). Facts in favor of the latter assumption were obtained in one of our works, where it turned out that in persons with greater visual sensitivity and, accordingly, with weak nerve cells, conditioned photochemical reactions are formed much faster than in subjects with the opposite characteristic of the visual analyzer (V. D. Nebylitsyn, 19596). Similar data are presented by L. B. Ermolaeva-Tomina (1963) based on the material of conditional GSR, which in “weak” individuals formed on average 2 times faster than in “strong” ones.
In other words, the organization of the sensory apparatus of the weak nervous system is such that it allows its carriers in many cases to avoid danger, instead of "face-to-face" with it, to find food by subtle signs that elude competitors, and finally develop a system of response and behavior. based on taking into account such signals and signs that are insufficient for more enduring, more efficient, but less sensitive (and in a sense, less reactive) individuals with a strong nervous system.
It can be assumed that it is precisely in these features of a weak nervous system that one of the sources of its biological advantage lies, giving it the opportunity to successfully compete in competitive struggle in those areas of life where the advantages of sensory organization come to the fore.
So, on a specific example of the relationship between weakness and sensitivity, the general rule is confirmed that “each property of the nervous system is a dialectical unity of manifestations that are opposite in terms of vital value” (B.M. Teplov, 1963, p. 25–26) .

5.1. Strength of the nervous system

The concept of the property of the strength of the nervous system was put forward by I.P. Pavlov in 1922. When studying conditioned reflex activity in animals, it was found that the greater the intensity of the stimulus or the more often it is used, the greater the response conditioned reflex reaction. However, when a certain intensity or frequency of stimulation is reached, the conditioned reflex response begins to decrease. In general, this dependence was formulated as a "law of force" (Fig. 5.1).

It was noted that in animals this law manifests itself in different ways: transmarginal inhibition, at which a decrease in the conditioned reflex response begins, occurs in some animals at a lower intensity or frequency of stimulation than in others. The former were referred to the “weak type” of the nervous system, the latter to the “strong type”. Two methods of diagnosing the strength of the nervous system have also emerged: by the maximum intensity of a single stimulus that does not yet lead to a decrease in the conditioned reflex reaction (measurement of strength through the “upper threshold”), and by the largest number of stimuli, which also does not yet lead to a decrease in the reflex response (measurement strength through her "endurance").

In the laboratory of B. M. Teplov, a greater sensitivity was found in persons with a weak nervous system compared to those who had a strong one. Hence, another way of measuring strength arose: through the speed of a person's response to signals of different intensities. Subjects with a weak nervous system, due to their higher sensitivity, respond to weak and medium-strength signals faster than subjects with a strong nervous system. In fact, in this case, the strength of the nervous system is determined by the "lower threshold".

Rice. 5.1. Diagram showing the manifestation of the "law of power". Vertically is the magnitude of the reaction; horizontally- the power of destruction.

In the same research team, the strength of the nervous system began to be determined by the level of EEG activation. However, this method is technically difficult for mass surveys. Until recently, all these methods of measuring the strength of the nervous system did not have a single theoretical justification and therefore were considered independent of each other, revealing various manifestations of the strength of the nervous system, associated, as it seemed, with different physiological mechanisms. Therefore, the requirement to study the typological manifestations of properties by several methods at once was also justified, as was discussed in the previous paragraph. However, a unified explanation of the various manifestations of the strength of the nervous system is possible (EP Ilyin, 1979), which makes the various methods equal in rights, with the help of which the strength of nervous processes is established. The unifying factor was resting activation level(a judgment about which was made on the basis of the level of energy expenditure at rest - Fig. 5.2): in some people it is higher, while in others it is lower. Hence the differences in the manifestation of the "law of power".



Rice. 5.2. Distribution of subjects with different energy expenditures at rest (activation level) in groups with different strengths of the nervous system. Vertically - number of persons, 5; horizontally - energy consumption level (kcal/kg/h): I – from 0.50 to 0.99; II - from 1.00 to 1.50; III - from 1.51 to 2.00; IV - from 2, 01 and above. A - persons with low strength of the nervous system; B - persons with an average strength of the nervous system; B - persons with great strength of the nervous system.

Strength of the nervous system as reactivity. For the appearance of a visible response (sensation of the stimulus or movement of the hand), it is necessary that the stimulus exceed a certain (threshold) value, or at least reach it. This means that this stimulus causes such physiological and physico-chemical changes in the irritated substrate that are sufficient for the appearance of a sensation or a motor response. Therefore, in order to receive a response, it is necessary to reach the threshold level of activation of the nervous system. But in a state of physiological rest, the latter is already at a certain level of activation, however, below the threshold. In subjects with a weak nervous system, the level of activation at rest is higher (this follows from the fact that at rest they have higher oxygen consumption and energy expenditure per 1 kg of body weight); accordingly, they are closer to the threshold level of activation from which the response begins (Fig. 5.3) than individuals with a strong nervous system. To bring this level to the threshold, as follows from the scheme, they need a less intense stimulus. Subjects with a strong nervous system, in which the level of resting activation is lower, require a large amount of stimulus to bring the level of activation to the threshold. This is the reason for the differences between “weak” and “strong” on the lower threshold irritation ( r 1 < r 2). With an increase in the intensity of single stimuli, the level of activation (excitation) and the magnitude (or speed, as in measuring reaction time) of the response increase. However, subjects with a weak nervous system, having begun to react earlier than those with a strong nervous system, reach the maximum level of activation earlier, at which the largest and fastest responses are observed. After that, the response effect decreases in them, while in subjects with a strong nervous system it still increases. They reach the activation limit later, with a greater strength of a single stimulus ( R 1 < R 2). Consequently, the "upper" threshold for the "weak" is lower than for the "strong", i.e., the exorbitant inhibition in the former occurs earlier than in the latter, at a lower intensity of a sufficiently strong stimulus (Fig. 5.3).

Rice. 5.3. Diagram showing differences in the strength of the nervous system depending on the intensity of the stimulus. Vertically - activation level: a 1 - at rest in persons with a weak nervous system; a 2 - in persons with a strong nervous system; bottom solid line- the threshold level of rest activation, from which the reaction to the stimulus begins; upper solid line– limiting level of response (A 1 - for people with a weak nervous system; BUT 2 - for people with a strong nervous system). Horizontally - stimulus intensity: r1– the lower threshold for persons with a weak nervous system, r2 R1- upper stimulus threshold for persons with a weak nervous system, R2- the same for persons with a strong nervous system; h1- the amount of additional activation required to reach the threshold of response by persons with a weak nervous system, h2- the same for people with a strong nervous system.

To identify these differences in people's responses to stimuli of different intensities, a technique developed by V. D. Nebylitsyn and briefly called the "slope of the curve" is aimed (Fig. 5.4; see the description of the technique in the Appendix). V. D. Nebylitsyn hypothesized that the range between the lower ( r) and upper ( R) thresholds should remain unchanged from individual to individual:

R : r = const.

Rice. 5.4. Change in reaction time to sound signals of different intensity in persons with a strong and weak nervous system. Vertically– reaction time, ms; horizontally is the sound volume, dB. solid line– data for persons with a strong nervous system; dash-dot - for people with a weak nervous system. dotted line the zone of weak and medium sound intensities used in the technique of V. D. Nebylitsyn is indicated.

It follows from the above formula that both a strong and a weak nervous system must withstand the same magnitude of the gradient (increase) of the suprathreshold stimulus. If we take the absolute threshold as the zero reference point of the quantity physiological the strength of the stimulus, then with an increase in its strength, both the strong and weak nervous systems will react in the same way: the strength of the stimulus will double - the magnitude of the response from both the strong and weak nervous systems will increase by the same amount. It should also follow from this that there will be no differences between the latter when the physiological strength of the stimulus is equalized; in both nervous systems, transcendental inhibition will occur at the same physiological strength of the stimulus. This means that the course of the response curve to stimuli of different physiological strengths of the strong and weak nervous systems will coincide. Thus, according to this hypothesis of V. D. Nebylitsyn, differences in the strength of the nervous system are found because a physical scale of stimulus intensity is used, in which the same physical value of the latter is a different physiological force for a strong and weak nervous system. The reason for this, as it has now become clear, is their different background activation: the higher it is, the greater the physiological strength of the physical stimulus becomes.

However, this plausible hypothesis by VD Nebylitsyn remains unproven in practice. Moreover, P. O. Makarov (1955) used the difference between the upper and lower thresholds as an indicator of the strength of the nervous system: the greater the range between the thresholds (which the author took as the energy potential), the greater the strength of the nervous system. However, this hypothesis also remained untested experimentally.

The strength of the nervous system as endurance. Repeated repeated presentation of an stimulus of the same strength at short intervals causes the phenomenon of summation, i.e., an increase in reflex reactions due to an increase in background activation, since each previous excitation leaves a trace, and therefore each subsequent reaction of the subject begins at a higher functional level than the previous one (shaded area in Figure 5.5).

Rice. 5.5. Diagram showing differences in the strength of the nervous system depending on the duration of the stimulus. Vertically– activation level (the designations are the same as in Fig. 5.3). Horizontally- the intensity of the stimulus (axis B) and the duration of the stimulus (axis T) with a constant intensity R2. The area of ​​summation of traces of excitation (an increase in the level of subthreshold activity) is shaded. t1- the time of action on the weak nervous system of the stimulus R2, leading to the achievement of the response limit; t2- the same for a strong nervous system.

Since the initial level of activation in subjects with a weak nervous system is higher than in subjects with a strong nervous system, the summation of excitation and the increase in response associated with it (despite the constant strength of the stimulus in terms of physical parameters) will reach the limit faster in them, and the “inhibitory” will come faster. effect, i.e. reduced response efficiency. In individuals with a strong nervous system, because of the lower activation of the rest, there is a greater "margin of safety", and therefore the summation in them can last longer without reaching the response limit. In addition, it is possible that the latter is at a higher level among the “strong” than among the “weak”. (This was not reflected in the diagram, where hypothetically the response limits for the “strong” and “weak” are indicated in the same way; the only thing that does not fit into this diagram is the case when the “weak” response limit will be greater than that of the “strong”. ) Since the summation of excitation is determined by the duration of the stimulus action (time ( t) or the number of repetitions of irritation ( n)), a strong nervous system is more enduring. This means that with repeated presentation of signals (external or internal - self-orders), the decrease in the effect of responding to them (the magnitude or speed of reactions) in the “weak” will occur faster than in the “strong”. This is the basis of various methods for determining the strength of the nervous system through its endurance. Two important points should be noted. First, weak stimuli should not be used in diagnosing the strength of the nervous system, since they reduce rather than increase the activation of the nervous system, and as a result, individuals with a weak nervous system are more tolerant of a monotonous stimulus. By the way, a dispute arose about this even in the laboratory of IP Pavlov: its head believed that those dogs that quickly fell asleep in the “tower of silence” when they developed conditioned reflexes had a weak nervous system. However, his student K.P. Petrova (1934) proved that these are just dogs with a strong nervous system that cannot withstand a monotonous environment (or, as they would say now, sensory deprivation). In the end, IP Pavlov admitted that the student was right.

Secondly, not every indicator of endurance can serve as a criterion for the strength of the nervous system. Endurance to physical or mental work is not a direct indicator of the strength of the nervous system, although it is associated with it. It should be about the endurance of nerve cells, not a person. Therefore, the methods should show the speed of development of transcendental inhibition, on the one hand, and the severity of the summation effect, on the other.

5.2. Mobility - inertia and lability of nervous processes

The property of the mobility of nervous processes, identified by IP Pavlov in 1932, was later, as noted by BM Teplov (1963a), to be assessed as more ambiguous. Therefore, he singled out the following features of nervous activity, characterizing speed of functioning of the nervous system:

1) the speed of occurrence of the nervous process;

2) the speed of movement of the nervous process (irradiation and concentration);

3) the speed of the disappearance of the nervous process;

4) the speed of change of one nervous process by another;

5) the speed of formation of a conditioned reflex;

6) ease of alteration of the signal value of conditioned stimuli and stereotypes.

The study of the relationship between these manifestations of the speed of the functioning of the nervous system, carried out in the laboratory of B. M. Teplov, made it possible to single out two main factors: the ease of altering the value of conditioned stimuli (positive to negative and vice versa) and the speed of occurrence and disappearance of nervous processes. B. M. Teplov left the name behind the first factor mobility, and the second is denoted as lability.

Other indicators of the speed of functioning of the nervous system do not currently relate to the two indicated properties. M. N. Borisova's attempt to single out the speed of irradiation and concentration of nervous processes as an independent property did not receive sufficiently weighty arguments. Also unsuccessful, as already mentioned, was an attempt by V. D. Nebylitsyn to single out the speed of formation of conditioned reflexes as a separate property of dynamism.

Although alteration is still used in a number of physiological works as an indicator of the mobility of the nervous system, data obtained in recent decades have called it into question as a reference indicator of the property of mobility. It turned out that the alteration of conditioned reflexes is a rather complex phenomenon of higher nervous activity, which is determined not only by the ease of transition of excitation into inhibition and vice versa, but also by the strength of the formed conditioned connections (i.e., the speed of decay of traces), the intensity of the stimulus, the influence of the second signaling system, and etc. (V. A. Troshikhin et al., 1978). Yes, and I. P. Pavlov himself regarded the alteration of conditioned stimuli as a very complex complex test, rather difficult to decipher.

The alteration is not associated with other indicators of mobility, in particular with indicators included in the lability group. But it reveals dependence on the strength of the nervous system. In this regard, the physiological interpretation of "remake" as a property of the nervous system is very difficult. At least, it is obvious that it is not a simple analogue of the speed of the course of nervous processes. Therefore, it is no coincidence that in the last two decades, indicators of the lability group, that is, the speed of development and disappearance of nervous processes, have been studied more. This is also facilitated by the fact that the "rework" requires a very long time, so it is impossible to refer to it during mass surveys.

Based on the fact that lability implies the speed of development of the nervous process and the speed of its disappearance, three methodological approaches have been outlined in the study of functional mobility (lability):

1) identification of the speed of occurrence of excitation and inhibition;

2) detection of the rapidity of the disappearance of excitation and inhibition;

3) identification of the maximum frequency of generation of nerve impulses, depending on both the first and the second.

Study of speed of development of nervous processes significantly complicated by the fact that it depends, as mentioned in the previous paragraph, on the level of activation of rest, i.e., on whether the nervous system of the subject is weak or strong. Of course, this does not exclude the influence on the rate of generation of excitation by other mechanisms that can directly characterize the proposed property of the nervous system. However, it is not yet possible to isolate them in a "pure" form. The situation is even worse when it comes to measuring the speed at which braking occurs. Now you can count on only one way - the measurement of the latent period of muscle relaxation using electromyography.

Functional mobility as the rate of disappearance of nervous processes. The nervous process does not disappear immediately after the action of the stimulus or the implementation of some action, but weakens gradually. The presence of traces prevents the normal development of the opposite nervous process. However, even having disappeared, the first process does not cease to influence the development of its opposite. The fact is that, according to the mechanism of induction, it is replaced by a phase that facilitates the emergence of such. For example, instead of the former process of excitation, a process of inhibition arises in the same centers. If, against this background, an inhibitory stimulus is acted upon, the resulting inhibition is added to the already existing inductive inhibition, and then the inhibitory effect is enhanced. The time unfolding of the ongoing changes is shown in fig. 5.6.

The aftereffect, which depends on trace depolarization and the circulation of nerve impulses through a network of neurons, has different durations for different people. In some, the positive and negative phases proceed quickly, in others - slowly. Therefore, if different people are presented with the same tasks of bringing together positive and inhibitory stimuli or excitatory and inhibitory reactions, different time sweeps of ongoing trace changes are revealed, i.e., differences in the functional mobility of the nervous system.

Rice. 5.6. Scheme showing the phases of the development of trace processes. A - change in the magnitude of inhibitory reactions after the excitation process precedes; B - change in the magnitude of activating reactions after the precedence of inhibitory reactions. columns the magnitude of the reactions is indicated, curved lines- change in time of nervous processes (t0-t5): trace excitation, a1 - disappearance of traces of excitation, a2-a4 - inhibition developing according to the mechanism of negative induction; b0 is trace inhibition, b1 is the disappearance of trace inhibition, b2–b5 is excitation developing according to the type of positive induction.

Since the duration of the attenuation of traces of nervous processes may depend on their intensity (the more intense the process, the longer its attenuation will be), it is important to take into account the influence of this factor. In persons with a weak nervous system, under the action of the same stimulus, the excitation process develops more intensively (at least within the limits of weak and medium-intensity stimuli), while its attenuation will be longer than in people with a strong nervous system. It is no coincidence that in the psychophysiological laboratory of B. M. Teplov - V. D. Nebylitsyn, positive links were found between inertia and weakness of the nervous system. However, when leveling the differences in the level of rest activation by different methodological methods, it is possible to obtain an indicator of the speed of the trace processes in its pure form. So, no correlations were found between the strength of the nervous system and the mobility of nervous processes when using the methods of K. M. Gurevich and E. P. Ilyin to identify the aftereffect, which will be discussed below (see Appendix). Methods that study functional mobility by the speed of the course of trace phenomena are most often based on the fact that after a positive signal that initiates an excitatory process, an inhibitory signal is presented that causes the opposite process or reaction. Conversely, after an inhibitory signal (or reaction), a positive signal is presented after a short time, causing an excitatory reaction. These techniques are very close to the technique called by I. P. Pavlov "bump". However, they are not identical to the technique called "remaking" of the signal meaning of stimuli, although in both cases there is an outwardly similar moment: one nervous process (or reaction) must give way to another.

The difference between these two methods, as noted by V. A. Troshikhin and his co-authors, is as follows. With a "collision", the change of one nervous process by another is due to the sequential action two different signals or operations(for example, sound as a positive stimulus and light as a negative one). When “reworking”, the signal value of one and the same conditioned stimulus changes, remaining unchanged in its modality and physical parameters. When there is a collision, there is a collision at the same moment in time two processes, in the "alteration" - multi-temporal change of positive and inhibitory stimuli. "Alteration" is associated with the extinction of a strengthened conditioned reflex reaction and the development of a conditioned brake on the same stimulus.

5.3. Balance of nervous processes

The ratio of nervous processes was the first of the properties of the nervous system indicated by IP Pavlov. Despite this, it is still the least studied. In any case, we cannot say that we are studying the balance of nervous processes as IP Pavlov understood it (we recall that he spoke about the balance in terms of the strength of excitation and the strength of inhibition). We cannot say so, because we do not know how to determine the strength of the braking process. Instead, we judge (by indirect signs) the prevalence or balance of excitatory and inhibitory reactions in human actions.

Various researchers of the Pavlovian school used as indicators of this property: the magnitude of positive and inhibitory conditioned reflex reactions, the ratio of the number of errors (or correct reactions) to a positive and inhibitory signal, the constancy of the background of conditioned reflex activity, etc. (E. P. Kokorina, 1963; G. A. Obraztsova, 1964, etc.).

In psychology, when measuring the balance of nervous processes in a person, other indicators are used: the number of translations and shortcomings during playback based on proprioception (when vision is turned off) of the amplitude of movements, as well as time periods (G. I. Boryagin, 1959; M. F. Ponomarev, 1960 , and etc.). According to these researchers, the presence of translations indicates the predominance of excitation, and the presence of non-arguments indicates the predominance of inhibition.

These ideas are confirmed both in experiments with pharmacological effects on humans and in studies conducted on a different emotional background of the subject. Thus, the intake of caffeine, which enhances excitation, leads to an increase in differentiation breakdowns (by which the severity of inhibition is judged) and an increase in the number of translations during reproduction of movement amplitudes. The intake of bromine, which enhances the inhibitory process, reduces the number of breakdowns in differentiation and increases the number of shortcomings in the reproduction of amplitudes (G. I. Boryagin, M. F. Ponomarev). In the state of pre-start excitement, recorded both by the self-report of athletes and by a number of physiological indicators (pulse, blood pressure, tremor, etc.), the number of translations of reproducible movement amplitudes increases sharply, and in a state of lethargy (with boredom, drowsiness) it increases number of failures.

However, all this indicates the relationship between excitation and inhibition according to their size (intensity), but not in terms of strength in terms of endurance of the nervous system, as IP Pavlov understood the balance. However, it so happened that the balance was always meant precisely in Pavlovian interpretation, and no one paid attention to the fact that it is easiest (and closer to the truth) to talk about the ratio of the magnitude of excitation and inhibition and study the influence of this particular ratio on behavior and activity. person. At least, the methods available to physiologists and psychologists for studying the balance of nervous processes make it impossible to count on more.

A feature of studying the balance between excitation and inhibition in terms of their magnitude is that it is judged by integral the characteristic resulting from the confrontation of these two processes (or response systems - excitatory and inhibitory). Thus, in different people, it is not the severity of excitation or inhibition that is compared, but which of the processes takes precedence over the other. Therefore, theoretically, the same typological feature in two subjects (for example, the predominance of excitation over inhibition) can be based on different levels of expression of both. So, in one subject, the predominance of excitation over inhibition occurs at a high intensity of both, and in the second, the predominance of excitation can be observed when they are weakly expressed.

An attempt to understand more deeply the physiological essence of this property has led to the identification of a number of interesting facts, which, however, do not provide a definitive answer. For example, it was found that balance, as well as the strength of the nervous system, is associated with the level of rest activation (EP Ilyin, 1999). However, if for the strength of the nervous system such a relationship is linear (the weaker the nervous system, the higher the activation at rest), then for the balance it is curvilinear: the level of activation (energy expenditure at rest per 1 kg of human weight) is higher in individuals with a balance of excitation and inhibition and lower in individuals with a predominance of excitation and inhibition (see Fig. 5.7).

Rice. 5.7. Energy consumption in a state of physiological rest in subjects with different typological features in terms of the balance of nervous processes. Vertically– energy consumption (cal/kg/h); horizontally- typological features in terms of balance. Shaded bars- "external" balance, unshaded- "internal" balance.

Such a curvilinear connection of balance with the level of activation of rest is confirmed by the presence of a curvilinear connection of balance with the strength of the nervous system: weakness of the nervous system often corresponds to the balance of nervous processes, and strength - imbalance (predominance of excitation or inhibition). In accordance with the discovered relationship, the balanced level of rest activation should on average be higher than that of the unbalanced ones (since the level of activation is higher for the "weak"). However, one circumstance attracts attention: the average level of rest activation in balanced people is lower than the same indicator in weak ones (probably because not all balanced people have a weak nervous system, i.e., the highest level of rest activation).

These facts, although they do not give a direct answer to the question of the physiological nature of the studied property of the nervous system, suggest that when considering the relationship between excitation and inhibition, one should obviously abandon the seemingly simple and obvious scheme: balance is a direct a line, at the upper end of which excitation dominates, and at the lower end - inhibition; balance is the middle point on this line, indicating the average severity of both processes. The data obtained do not fit into such a scheme: the predominance of excitation and the predominance of inhibition are not two poles of the same straight line, and the relationship between them is much more complicated, and balance is not an intermediate (middle) instance between them .

This assumption is supported by other facts. The first is that when measuring the "external" balance in the middle of the night, immediately after the subjects woke up, it was revealed that "excitable" and "inhibitory" according to daytime measurements passed into the category of balanced ones at night. If the transition of the former into balanced ones did not cause surprise and corresponded to ideas about the intensification of inhibitory processes during sleep, then the transition of "inhibitory" processes, which should be regarded as an increase in excitation, did not fit into the generally accepted ideas. True, such a transition was not observed in all subjects, but still the indicators of 9 out of 17 "excitable" and 12 out of 17 "inhibitory", which at night passed into the category of balanced (E. P. Ilyin and M. I. Semenov, 1969).

Attention was also drawn to the fact that at night the accuracy of reproduction increased, as if it became easier for the subjects to complete the task of the experimenter. This fact led to the idea that in a semi-drowsy state, people were freed from the motivational factor that pressed on them during the day and prevented them from acting liberatedly. Observation of the behavior of the subjects during the night experiment, when they had one desire - to get rid of the experimenter as soon as possible and continue sleeping, made it possible to suggest that both the worse reproduction accuracy and the frequent occurrence of cases with a predominance of excitation or inhibition during daytime measurements could be the result of the subject's desire to perform task of the experimenter as best as possible. At night, this "pressure" on the motor actions of the subjects either disappeared or was significantly weakened, hence, in both cases, the control of movements was different.

In another study, the interference of the desire to “do better” in the control of precision movements was eliminated thanks to hypnosis (E. P. Ilyin, S. K. Malinovsky, 1981). The subjects, whose balance was measured in the waking state, were introduced into the first stage of hypnosis, during which they performed the same test to determine the balance under the experimenter's command. Of the 16 people, 3 had a predominance of excitement in their usual state, and it was they who could not be put into a hypnotic state and find out if they had achieved balance. However, it was more important for us to find out whether persons with a predominance of inhibition would come to the latter (we selected 6 such people). Our expectations were confirmed: 5 out of 6 subjects in a state of hypnotic sleep turned into balanced ones.

Thus, the results of the experiment with the interruption of natural night sleep were confirmed. And this means that in a half-asleep state our subjects released both from inhibitory and excitatory influences on the control of movements on accuracy in space. What caused these influences, one can only guess (most likely they stem from the frontal regions of the cerebral hemispheres, in which there are integrative centers that are in charge of human conscious acts). When such influences are blocked during sleep, the movement control centers switch to an automated and more optimal mode. Accordingly, it can be assumed that the balance of nervous processes is the initial basic characteristic in the automated mode of operation of the nerve centers, and the predominance of excitation or inhibition is a distortion of this ratio of nervous processes as a result of the intervention of another level of control associated with actively attracting a person’s attention to the task being performed, with his desire do it the best you can. What relationship between excitation and inhibition will manifest in a given person probably depends on his type of response to the situation: some have a typical excitatory reaction, others have an inhibitory one, while others have an indifferent reaction or none at all, so they show a basic the ratio between excitation and inhibition, i.e., their balance.

Despite the fact that this explanation of the nature of the balance is nothing more than a hypothesis, only it allows, at this level of our knowledge, to somehow explain those facts with changes in the balance and its connection with the level of rest activation that have been revealed. Only one thing is clear: the essence of the property of balance in terms of the magnitude of excitatory and inhibitory reactions needs further study, and along this path we are likely to expect many more unexpected things.

There is reason to believe that the balance between the magnitude of excitation and inhibition in different circuits of regulation of the central nervous system is expressed differently. So, in addition to the balance, which was discussed above and called "external", there is another type of balance, called "internal". It received such a name because, on the one hand, it does not respond to changes in the emotional state of a person, for example, to prelaunch excitement; on the other hand, it reflects the level of activation associated with the need for motor activity, i.e. this balance is associated with deeper (internal) processes in the central nervous system.

The non-identity of the "external" and "internal" balance shows a number of facts. First, there are no direct correlations between them (neither positive nor negative). Secondly, in a number of human states (monotony, mental satiety), shifts in these balances are multidirectional: a shift of the "external" balance towards excitation corresponds to a shift of the "internal" towards inhibition, and a shift of the "external" balance towards inhibition corresponds to a shift " internal" towards excitement. This is due to the mechanisms of self-regulation of the level of activation in the central nervous system, the "transfusion" of activity from one level of regulation to another (A. A. Krauklis, 1963). Thirdly, the “external” and “internal” balance have their own specific manifestations in the behavior and activities of athletes, which is also reflected in how often there are typological features of the manifestation of these properties in representatives of various sports. For example, if the predominance of excitation according to the "external" balance is more typical for athletes specializing in the "short" sprint, then the predominance of excitation according to the "internal" balance is inherent in athletes who prefer the "long" sprint, which requires speed endurance.

Perhaps, in these two types of balance, two activation systems manifest themselves - the reticular formation and the hypothalamus. However, the very existence of these systems as independent ones is disputed by some physiologists.

The “internal” balance is also connected by a curvilinear dependence with the level of rest activation: the highest level of this is observed in people with balance (however, it is lower than in people with balance according to the “external” balance).

What are the features of a weak nervous system? This question interests many. With each generation, the number of people with a weak nervous system increases significantly.

However, both strong and weak systems have their own certain undeniable advantages.

Strength of the nervous system

By definition, the strength of the nervous system of each person is an innate indicator. We must agree that this is simply necessary to indicate the endurance and performance of all nerve cells in the human body. The strength of the nervous system allows its cells to withstand any excitation without turning into inhibition.

The latter is a vital component of the nervous system. It is able to coordinate all its activities. A distinctive ability of a strong system is that people who possess it are able to survive and withstand even super-strong stimuli. People with a weak system, on the contrary, do not hold the signal well and react poorly to stimuli.

A person with a weak nervous system is not distinguished by patience, with great difficulty retains the information that has come to him and, at the first opportunity, shares it with almost the first person he meets.

From all of the above, we can already conclude that people with a weak system are simply not able to tolerate strong stimuli.

In such situations, the system either slows down, or completely “disappears” without any brakes. However, it also has advantages, such as the ability to hypersensitivity. It can also easily distinguish between ultra-weak signals.

The main signs of a weak nervous system

A weak nervous system in humans has the following symptoms:

  1. Indifference. Such a signal can make a person accept all kinds of blows of fate without any protest. A weak nervous system makes people lazy both mentally and physically. At the same time, people, even living in poverty, will not make any attempts to correct the situation and change their position in society.
  2. Indecision. A person who is dominated by hypersensitivity is able to obey everyone. Worst of all, this person can be taken over to such an extent that he simply turns into a living robot.
  3. Doubts. Sensitive people are able to doubt not only themselves, but also people who are trying to help them in every possible way. Such people very often justify themselves in order to cover up their own failures. Very often this is expressed in envy of those people who are better and more successful than them.
  4. Anxiety. This signal is central to the greatly reduced nerve strength. Anxiety can lead a person to a nervous breakdown and even a breakdown. Often worried people are almost the most miserable creatures on the entire planet. They live in constant fear. It is worth noting that anxiety can take away vitality and prematurely age a person. Such people, as an excuse, are accustomed to saying a long-learned phrase: “You should have my worries and worries, you would have worried no less.”
  5. Each person has their own specific concerns, and often they face great life difficulties. But a person with a healthy system meets such difficulties quite calmly and tries to find a solution in the current situation. Excessive worry will not help solve the problem, but it can pretty much undermine your health and bring old age closer. In other words, anxiety is a weapon against yourself.
  6. Overcaution. A person constantly waits for the right moment to implement his own ideas and plans. And this expectation can turn into a habit. Pessimism grows very strongly in these people, they can only be confused by one bad thought that failure can happen and everything will collapse. People with extreme caution risk indigestion, rather weak blood circulation, nervousness and many other negative factors and diseases.

Features of education with a weak nervous system in children

Basically, everyone is accustomed to seeing cheerful, cheerful and active children, but among them there are also quite passive, very self-contained and very poorly withstand even the slightest stress. They are very impressionable and overly sensitive to the slightest stimuli.

Parents need to remember that highly impressionable children need a special approach. In this case, mistakes in education can lead not only to the child's fearfulness and irritability, but also to various kinds of illnesses and even to a nervous breakdown.

First of all, you need to think over the daily routine necessary for the life of the child, both at home and outside its walls. The most important factor for energy expenditure is such a regimen, which is directly related to the stability and rhythm that children with a weak nervous system sorely need.

Very important for these children is the schedule by which they will live. The mode, of course, is capable, but is it necessary to limit the child and put him in new living conditions? Certainly, but just do not forget to take into account the inclinations of your baby and his condition. Changing the regimen for a child is appropriate only if nothing really tires him. For example, such changes in his life can be dealt with during the summer holidays.

The fact is that during the rest of the students, their usual routine is lost. It is very important for such children to see and learn something new and interesting every day. For example, hiking can give a child vigor, vitality and strength.

The concept of the strength of the nervous system was put forward by I.P. Pavlov in 1922. When studying the conditioned reflex activity of animals, it was found that the greater the intensity of the stimulus or the more often it is used, the greater the response conditioned reflex reaction. However, when a certain intensity or frequency of stimulation is reached, the conditioned reflex response begins to decrease. In general, this dependence was formulated as a "law of force" (Fig. 5.1).

It was noted that this law manifests itself differently in animals: in some animals, transcendental inhibition, at which a decrease in the conditioned reflex response begins, occurs at a lower intensity or frequency of stimulation than in others. The former were referred to the “weak type” of the nervous system, the latter to the “strong type”. Two methods of diagnosing the strength of the nervous system also arose: by the maximum intensity of a single stimulus, which still does not lead to a decrease in the conditioned reflex reaction (measurement of strength through the "upper threshold"), and by the largest number of stimuli, which also does not yet lead to a decrease in the reflex response (measurement of strength through her endurance).

In the laboratory of B. M. Teplov, a greater sensitivity of persons with a weak nervous system was revealed in comparison with persons with a strong nervous system. Hence, another way to measure the strength of the nervous system arose - through the speed of a person's response to signals of different intensities: subjects with a weak nervous system, due to their higher sensitivity, react to weak and medium-strength signals faster than subjects with a strong nervous system. In fact, in this case, the strength of the nervous system is determined through the "lower threshold".

In the same research team, the strength of the nervous system began to be determined by the level of EEG activation. However, this method is technically difficult for mass surveys.

Until recently, all these methods of measuring the strength of the nervous system did not have a single theoretical justification and therefore were considered as independent of each other, as revealing various manifestations of the strength of the nervous system, as based on different physiological mechanisms. Hence the requirement to study the typological manifestations of properties by several methods at once, about than mentioned in Chapter 4. Nevertheless, a single explanation of the various manifestations of the strength of the nervous system is possible (E.P. Ilyin, 1979), which makes equal the various methods by which the strength of nervous processes is studied. The factor that unites these methods was the level of activation at rest (judgment which was taken out on the basis of the level of energy expenditure at rest - Fig. 5 2). in some people it is higher, while in others it is lower. Hence the differences in the manifestation of the "law of power".

Strength of the nervous system as reactivity. In order for a visible response to occur (sensation of a stimulus or hand movement), it is necessary that the stimulus exceed or at least reach a certain (threshold) value. This means that this stimulus causes such physiological and physico-chemical changes in the irritated substrate that are sufficient to the appearance of a sensation or a response motor reaction. Therefore, in order to receive a response, it is necessary to reach the threshold level of activation of the nervous system. But in a state of physiological rest, the nervous system is already at a certain level of activation, although below the threshold. In subjects with a weak nervous system, the level of activation at rest is higher ( which follows from the fact that at rest they have higher oxygen consumption and energy expenditure per kilogram of body weight), therefore, they are closer to the threshold level of activation from which the response begins (Fig. 5.3) than individuals with a strong nervous system. In order to bring this level to the threshold, they, as follows from the diagram, need a less intense stimulus. Subjects with a strong nervous system, in which the level of resting activation is lower, require a large amount of stimulus to bring the level of activation to the threshold. Hence the differences between "weak" and "strong" in terms of the lower threshold of irritation (r,< г2).

The strength of the nervous system as endurance. Repeated repeated presentation of an stimulus of the same strength at short intervals causes the phenomenon of summation, i.e., an increase in reflex reactions due to an increase in background activation, since each previous excitation leaves a trace behind and therefore each subsequent reaction of the subject begins at a higher functional level, than the previous one (shaded area in Figure 5.5).

Since the initial level of activation in subjects with a weak nervous system is higher than in subjects with a strong nervous system, the phenomenon of summation of excitation and the increase in response associated with it (despite the constant strength of the stimulus in terms of physical parameters) will quickly reach the limit of response in them and the “inhibitory » effect, i.e. reduced response efficiency. In individuals with a strong nervous system, due to lower rest activation, there is a greater "margin of safety", and therefore the summation can continue for a longer time without reaching the response limit. In addition, it is possible that the response limit for the “strong” is at a higher level than for the “weak” (this was not reflected in the diagram, where hypothetically the response limits for the “strong” and “weak” are indicated the same; the only thing is that does not fit into this scheme - this is the case when the “weak” response limit will be greater than that of the “strong”). Since the magnitude of the summation of excitation is determined by the duration of the action of the stimulus (the time t or the number of repetitions of the stimulus n), a strong nervous system is more enduring. This means that with repeated presentation of signals (external or internal - self-orders), the decrease in the effect of response to these signals (the magnitude or speed of reactions) in the "weak" will occur faster than in the "strong". This is the basis of various methods for determining the strength of the nervous system through its endurance.

Two important points should be noted. First, when diagnosing the strength of the nervous system, weak stimuli should not be used, since they reduce rather than increase the activation of the nervous system, and as a result, individuals with a weak nervous system are more tolerant of a monotonous stimulus. By the way, a dispute arose about this even in the laboratory of I. I. Pavlov: I. P. Pavlov believed that those dogs that quickly fell asleep in the “tower of silence”, when they developed conditioned reflexes, had a weak nervous system. However, his student K. P. Petrova (1934) proved that these are just dogs with a strong nervous system that cannot withstand a monotonous environment (or, as they would say now, sensory deprivation). In the end, IP Pavlov admitted that the student was right.

Secondly, not every indicator of endurance can serve as a criterion for the strength of the nervous system. Endurance to physical or mental work is not a direct indicator of the strength of the nervous system, although it is associated with it. It should be about the endurance of nerve cells, not a person. Therefore, the methods should show the speed of development of transcendental inhibition, on the one hand, and the severity of the summation effect, on the other.

The concept of the basic properties of the nervous system. Main points

The properties of the nervous system are its natural, innate features that affect individual differences in the formation of abilities and character (Pavlov).

The main properties of the nervous system (Pavlov):

1) The strength of the nervous system is an indicator of the performance, endurance of nerve cells when exposed to repetitive or superstrong stimuli. The main sign of the strength of the nervous system in relation to excitation is the ability of the nervous system to withstand, without revealing prohibitive inhibition, prolonged or frequently repeated excitation. The greater the strength of the nervous system, the higher the thresholds of sensitivity. The main sign of the strength of the nervous system in relation to inhibition is the ability to withstand prolonged or frequently repeated action of an inhibitory stimulus.

Teplov: the strength of the nervous system is manifested not in what the productivity of a given person is, but in what ways and under what conditions he achieves the greatest productivity.

2) Balance (or balance of nervous processes) - the ratio of the main nervous processes (excitation and inhibition) involved in the development of positive or negative conditioned reflexes.

3) The mobility of nervous processes - the speed of alteration of the signs of stimuli and the speed of the onset and cessation of nervous processes. The ability of the nervous system to quickly respond to changes in the environment, the ability to move from one conditioned reflex to another, depending on the environment.

Currently, some physiologists, instead of the property of balance, speak of dynamism - the ease with which the nervous system generates the process of excitation or inhibition. The main feature of this property is the speed of development of conditioned reflexes and differentiations. Also, from the property of mobility, the property of lability is distinguished - the rate of occurrence and termination of the nervous process.

Each of these properties can be different in relation to the processes of excitation and inhibition. Therefore, it is necessary to speak about the balance of nervous processes for each of these properties.

Typology of GNI according to Pavlov

"Type of VND" was used by Pavlov in two senses:

1) The type of VND is a combination of the main properties of the processes of excitation and inhibition;

2) Type of GNI - a characteristic "picture" of the behavior of a person or animal.

GNI properties Type Title of Hippocrates Main functional characteristics
Force Weak melancholic The development of conditioned reflexes is difficult.

Easily develops external inhibition

The development of conditioned reflexes proceeds easily. Extinction proceeds slowly
balance, strength Strong, unbalanced

Strong, balanced

 Choleric The development of positive conditioned reflexes is facilitated, negative - difficult.

The development of both positive and negative conditioned reflexes is facilitated
Mobility, strength, balance Strong, balanced, inert

Strong, balanced, mobile

 Phlegmatic person

sanguine

 Alteration brake. conditioned reflexes to excitation. difficult

Alteration brake. conv. reflexes to excitation. relieved.

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