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M L Pigareva

Publications and source records attributed to M L Pigareva.

At least 19 recordsLinked to original sources
PubMed1974

Elaboration of conditioned alimentary reflexes having different probabilities of reinforcement in rats with hippocampal lesions.

A motor alimentary conditioned reflex was elaborated in hippocampectomized and intact albino rats. Food reinforcement followed 100 percent, 50 percent, 33 percent or 25 percent of conditional stimulus presentations (click from a rotating food box). No differences were found in the rate of conditioned alimentary reflex elaboration between the hippocampectomized and control rats at 100 percent and 50 percent reinforcement, although the time-courses of formation of the conditioned reflex connection differed substantially. With low reinforcement probabilities (33 percent and 25 percent) the operated rats, unlike the intact ones, exhibited no adequate responses throughout the 10 experimental days. The results obtained corroborate an earlier suggestion that the hippocampus is involved in the organization of behavior the reinforcement probability of which is unknown or relatively low.

Acoustic Stimulation↗
PubMedDate not supplied

Comparative psychological approach to the analysis of the functions of the hippocampus.

As compared with dogs, the development of conditioned reflex switching-over of heterogeneous conditioned reflexes in intact rats is often accompanied by the development of reactions of the neurotic type. Experiments involving injury of the hippocampus (in rats) and the recording of electrical activity (in dogs) showed that this structure participates in the formation of conditioned reflex switching-over of instrumental reflexes. Following the injury to the hippocampus, the rats successfully formed the switch-over. The switch-over signal altered the electrical activity of the hippocampus in the dogs. Consequently, the hippocampus in both species of animals belongs to the system of structures which participate in the formation of conditioned reflex switching-over. Hippocampectomized rats were not capable of developing an alimentary conditioned reflex at the 30% level of reinforcement. The highest values of the frequency of the hippocampal theta rhythm were obtained in the dogs at just this level of probability of reinforcement. These data indicate that the assurance of reactions to signals with a low probability of reinforcement is an important function of the hippocampus in various species of animals.

Animals↗
PubMedDate not supplied

Sensory information--the major factor of ontogeny.

On the basis of their own data authors postulate that the increase in sensory input during early ontogeny results in a delay in the development of the sensory systems formed earlier. In connection with this, the sensory basis of behavioral patterns becomes ineffective, causing their reorganization and the appearance of new forms of behavior. Limitation of sensory input during during the critical periods of development stimulates the accelerated manifestation of behavioral patterns. However, this acceleration also has long-lasting negative effects - alterations in the process of learning and memory in adult animals.

Aging↗
PubMedDate not supplied

[Avoidance reactions to painful stimulation of another individual following destruction of the rat amygdala].

Experiments in male albino rats have shown that bilateral lesion of the amygdala does not prevent avoidance conditioning to pain stimulation of another rat, improvement of the reaction after a painful action of the experimental animal and its extinction after the discontinuation of pain stimulation of the partner. Amygdalectomy performed after elaboration of a conditioned avoidance reaction, improves or worsens it, depending on which of the two rivaling motivations (sensitivity to signals of the other animal or fear of an open field) relatively predominanted in the given animal before the operation. The facts obtained suggest that the amygdala may be classified as belonging to the system of brain structures, where the "interrupting function" of emotions is achieved directing the behaviour to meet the predominant need.

Amygdala↗
PubMedDate not supplied

[The dependence of the emotional state of 8- to 9-year-old children on the conditions of play].

Dependence was studied of emotional state of children, aged 8-9, on the terms of computer play: without additional instruction (with a strategy typical of the child), at time deficiency and at demonstration of techniques of play without limitation in time. Prior to and during the play the following parameters were recorded: heart rate (HR); frequency of basis tone (Fb.t.) and evaluation of frequency of the first formant (n(0] of the vowel "a" in the word "da" pronounced by the child during the play in response to acoustic signal; reaction time (RT) to acoustic signal; parameters of playing activity and also spontaneous verbal expressions of children. Increase of emotional stress during the play at time deficiency was accompanied by the most expressed changes of HR, RT, Fb.t., worsening of playing activity and the increase of the number of negative emotional reactions. When playing without additional instruction, the children showed the best results of playing activity, accompanied by the least expressed changes of HR and Fb.t. in comparison with the background at the greatest expressiveness of the n(0) change, and predominantly positive emotional reactions. The analysis of the correlation of the motivational and informational characteristics of the studied playing activity allowed to make a conclusion about preferential connection of HR and Fb.t. with the motivational and n(0) with informational components of the playing activity.

Child↗
PubMedDate not supplied

[Prenatal experience and postnatal development of the rat hippocampus: sleep deprivation of pregnant rats].

The effects of sleep deprivation in pregnancy on the development of hippocampal function of the offspring have been investigated. For this purpose we compared electrophysiological characteristics in the hippocampal slices of 15-20-old-day rats of the control and two experimental groups. In the first experimental group the pups were taken from mother for weighting three times during the first postnatal week and then weekly. Another experimental group was brought up without handling. We found that CA1 population spikes developed to significantly less amplitude in experimental groups of rat pups. This phenomenon was observed at higher intensity of monosynaptic activation, although near-threshold stimuli didn't reveal any differences among groups. However, under paired-pulse stimulation (70 ms inter-pulse interval) small amplitudes in the hippocampal slices of experimental animals could facilitate up to control value, and second in pair responses didn't differ from corresponding control. Our data doesn't confirm the hypothesis about decreased connectivity in the hippocampus of experimental rats, but the efficacy of CA3-CA1 inputs seems to be lower. Besides excitatory transmission, the effectiveness of inhibition of paired-pulse facilitation at 15 ms inter-pulse interval was also significantly decreased. The observed effects of prenatal influences seem to develop under postnatal experience. We observed significant trend to more pronounced modifications upon age especially in the case of early handling and testing.

Animals↗
PubMedDate not supplied

[The mental developmental level of 5- to 7-year-old children and the reflection of their emotional status in speech].

In 22 children aged 5-7 during the play "make up a square" negative (1st step) and positive (2nd and 3rd steps) emotions were formed. General behaviour and speech expressions of children were recorded during the play. Before beginning of the play, intellectual development of children was tested, and two groups were singled out: with low (A) and high (B) levels of tasks solution. Changes of verbal values Fot and n(0) in children from two groups were compared during the play. Fot was most sensitive to the appearance of the emotional state. Emotional states were more expressed in children from group A: percentage of significant changes in Fot and n(0) values in comparison with the background was higher in the group A than in the group B. In children of the group A the negative emotion formed at the 1st step of the experiment caused a decrease of level of motivation to fulfillment of the task to make up a "difficult" square. In children of the group B the negative emotion did not cause any distinct decrease of motivation level. Fot reflects the change of motivational attitude to task) and n(0)--of informational (actualization of knowledge, reasoning etc.) components of the emotional reaction connected with the process of task solution.

Child↗
PubMedDate not supplied

[A comparative neuropsychological approach to the analysis of hippocampal functions].

Formation of conditioned switching-over of heterogeneous instrumental reflexes in dogs was more successful than in rats, which testifies about significant differences of the functional organization of analytical-synthetic brain activity in rodents and predatory animals. Experiments with lesion of the hippocampus (in rats) and the records of its electrical activity (in dogs) allowed to conclude that the hippocampus of the both types of animals belongs to the system of structures, participating in the formation of conditioned switching-over. The data, obtained in the process of elaboration of the switching-over and probabilistic reinforcement of the alimentary conditioned stimulus, testify that providing for the reactions to signals with low probability of reinforcement in different species of animals is one of the functions of the hippocampus.

Acoustic Stimulation↗
PubMedDate not supplied

[The influence of the emotional state of the child on the parameters of its verbal response].

The method of determination of human emotional state by speech was applied to the analysis of verbal expressions of 22 children during the play "make-up the square". Parameters of the verbal response--F0 (fundamental frequency) and n(0) (evaluation of the frequency of the first formant) changed to the greatest extent under the influence of emotional reactions which appeared in children during the play. Depending on the terms of the play different changes of these parameters took place in different children: in some cases significant increase of values was observed as compared with the background ones, in other cases--their significant decrease.

Child↗
PubMedDate not supplied

[Effect of hippocampal damage on emotional stress in rats].

Motor reactions and ECGs were recorded in rats with lesioned hippocampus and in intact animals during elaboration of conditioned switching over of heterogeneous conditioned reflexes (alimentary and defensive). In hippocampectomized rats, in contrast to intact ones, the formation of this complex conditioned activity is not accompanied by pronounced vegetative reactions and changes in the ECG. The data obtained point to an active involvement of the hippocampus in formation of emotional stress and confirm the concept of the hippocampus as a brain structure, providing for responses to signals of events with low probability.

Animals↗
PubMedDate not supplied

[Formation of alimentary conditioned reflexes with probable reinforcement in rats with frontal cortex injuries].

Alimentary conditioned response to the sound of turning of the feeding-rack reinforced in 33 and 25 per cent of cases was formed faster in rats with frontal cortical lesion than in intact animals. The results obtained permit to suppose that during integrative brain activity the frontal areas of the cerebral cortex participate in organization of behavior with a high probability of reinforcement.

Animals↗
PubMedDate not supplied

[Morphologic analysis of the consequences of simultaneous lesioning of the hippocampus and amygdala in the rat].

The comparison of damage localization in the region of the hippocampus and amygdala with changes of behaviour components in operated rats revealed an increase of alimentary excitability, motor and intersignal activity following damage of the dorsal part of the hippocampus and destruction of all the parts of amygdala, whereas the elaboration of transswitching of heterogeneous (alimentary and defensive) conditioned reflexes became difficult. If the hippocampus was fully destroyed and amygdala damage was confined to its corticomedial part, then the motor activity was enhanced only in some animals and alimentary excitability and intersignal activity, as a rule, did not differ from those in the intact rats. The elaboration of transswitching of heterogeneous conditioned reflexes in this case was facilitated.

Amygdala↗