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Biomedical subjects

E K Davydova

Publications and source records attributed to E K Davydova.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

[The role of the lateral and medial hypothalamus in reproducing a motor reaction as the signal during the acquisition of classical conditioned reflexes].

In experiments on three dogs there was shown that testing electrostimulation of the lateral hypothalamus reproduced the motor reaction which is a signal stimulus at elaboration of classic alimentary conditioned reflexes (CRs) and did not reproduce it at elaboration of classic defensive CR. Testing electrostimulation of medial parts of the hypothalamus reproduced, as LH electrostimulation the "signal" motor reaction, but in less percentage of cases, during elaboration of classic alimentary CRs and did not reproduce it at elaboration of classic defensive CRs. The reproduction of the signal motor reaction at LH electrostimulation is connected with activation of backward conditioned connection from motivation structures of the hypothalamus to representation of the signal stimulus in the motor cortex.

Animals↗
PubMedDate not supplied

[The role of the lateral and medial hypothalamus in reproducing food and escape instrumental reactions].

In experiments on two dogs it has been found that testing electric stimulation of the lateral hypothalamus reproduces instrumental movement in case of elaborated alimentary instrumental conditioned reflexes (CR) to a tone and does not reproduce it at elaborated acid-defensive instrumental CR. Under testing electric stimulation of the medial hypothalamus the instrumental movement practically is not reproduced neither in alimentary nor in defensive situation. Appearance of instrumental movement at LH electro-stimulation in alimentary situation is connected with activation of backward conditioned connection from motivation "alimentary" LH centre to representation of this movement in the motor cortex.

Acoustic Stimulation↗
PubMedDate not supplied

[Changes in excitability in the motor cortex of the dog during switching-over conditioned escape and avoidance reflexes].

Excitability of the motor cortex (projection of the foreleg), judged by the threshold of flexion reaction to its stimulation during elaboration of conditioned transswitching (CT), was studied in dogs. CT was elaborated for instrumental reflexes of escape (1-st CT variant) and avoidance (2-nd CT variant). In the 1-st variant the dog escaped from the hydrochloric acid solution, if during its administration it produced an active flexion of the foreleg in situation A and an active extension of the same leg in situation B, with a permanent action of a switch (a fan). In the 2-nd CT variant, the dog avoided the acid, if in situation A, in response to a tone of 250 Hz, it actively lifted its foreleg, and if in situation B, it actively resisted a passive lift in response to the same stimulus. In escape CT as well as in avoidance CT, there was a statistically significant difference between the thresholds of flexion reaction. The threshold was lower in situation of instrumental flexion reflex formation in comparison to the situation of extension reflex formation.

Animals↗
PubMedDate not supplied

[Formation of reverse conditioned connections during unrestrained behavior].

Reactions achieved by the mechanism of backward connection were studied in unrestrained dogs with acoustic stimuli preceded by an alimentary unconditioned reflex: a 300 c/s acoustic stimulus was paired with feeding from the left feeding trough and 1000 c/s stimulus--with the right feeding trough. A certain dynamics was observed in the manifestation of these reactions. As the number of tests increased, the number of specific reactions diminished, while non-specific reactions and reactions of running to the door appeared. Acute extinction of the running reflex to the sound of the feeding trough has been shown that the dynamics of reactions to the later is the same as in tests to the tone. Proceeding from this, it may be assumed that the evolution of backward connections manifestation is based on extinctive inhibition which develops in consequence of non-reinforcement of conditioned stimuli in the tests on backward connection formation.

Animals↗
PubMedDate not supplied

[Fromation of forward and reverse connections during elaboration of a classical and instrumental acid-defense conditioned reflex].

During elaboration of a classical acid defensive conditioned reflex to passive lifting of a foreleg in dogs, the reinforcing stimulus--acid elicited an extension of the leg via backward connection. At the initial stage of elaboration of an instrumental avoidance reflex, the reinforcing stimulus called forth an extension of the leg, whereas at the stage of a stable reflex it produced a flexion.

Acids↗
PubMedDate not supplied

[Changes in the excitability of the motor cortex during elaboration of conditioned reflex switching].

In the process of elaboration of conditioned transswitching of classical and instrumental alimentary and acid defensive reflexes, there was a change of excitability in the cortical projection of dog's forepaw. When flexor reaction elicited by stimulation of the motor cortex is used as signal stimulus, the character of functional reorganization in its cortical projection proves to be principally the same as at special elaboration of the motor cortex was used as a signal stimulus the thresholds of flexor reaction increased approximately equally in both experimental situations.

Animals↗
PubMedDate not supplied

[Forward and reverse connections in the presence of a combination of indifferent stimuli].

In pairing of auditory and photic stimuli, the first stimulus caused an orientation reaction typical of the second stimulus even before its action, while the "proper" reaction to the first stimulus was reduced. Difference between orientation reactions to "positive" and "differentiation" stimuli was revealed. If the "positive" stimulus evoked the orientation reaction typical of the second stimulus, and the proper reaction was weakened, then the differentiation stimulus elicited mainly the proper reaction or no orientation reaction at all. This seems to be due to the specialization of reactions of performed by means forward connection.

Acoustic Stimulation↗
PubMedDate not supplied

[Changes in the motor response threshold to direct electric stimulation of the motor cortex during elaboration of conditioned reflex switching-over].

During elaboration of switching-over of an alimentary salivary conditioned reflex to a defensive one in dogs, with foreleg passive flexion as a signal stimulus, excitability changes of opposite signs appeared in the cortical representation of the left foreleg. At the stage of elaborated switching-over, the threshold of the flexor reaction to a direct stimulation of the motor cortex became lower in the alimentary experimental situation (passive rise--milk) and rose in the defensive situation (passive rise--acid).

Animals↗
PubMedDate not supplied

[The role of emotiogenically positive areas of the hypothalamus in realizing instrumental food and escape reactions].

In experiments with dogs was shown that the activating electrostimulation (200 cps; 0.5 ms; 15-20 V) of the emotional positive structures of the hypothalamus (having been able to evoke self-stimulation) reproduced neither defensive nor alimentary adaptive motor reaction. Moreover, such a stimulation inhibited both alimentary (unconditioned and instrumental) and defensive instrumental conditioned responses.

Acoustic Stimulation↗
PubMedDate not supplied

[The "circular" interaction of the signal, motivational and emotiogenic structures in food and defensive (classical and instrumental) conditioned reflexes].

In experiments with dogs was shown the role of motivational and emotional structures of the hypothalamus in reproduction of the adaptive motor reaction both in classical and instrumental conditioned reflexes (alimentary and defensive). Change of parameters of electrostimulation gave a possibility to activate differentially the motivational, emotional negative, and emotional positive structures of the hypothalamus. Electrostimulation of the motivational structures reproduced alimentary but not defensive adaptive motor reaction and decreased the threshold of the motor reaction which was used as a signal during classical alimentary conditioning. Electrostimulation of the emotional negative structures reproduced defensive adaptive reaction and inhibited alimentary unconditioned response. Elaboration of the avoidance of the stimulation of the lateral hypothalamus was a proof for the activation of the emotional negative structures. Electrostimulation of the emotional positive structures which was used as an unconditioned stimulus during self-stimulation conditioning reproduced neither defensive nor alimentary conditioned response.

Adaptation, Physiological↗