[Analysis of the latent phase of audiogenic convulsions in rats by means of the conditioned reflex method].
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[Effect of urethane on the electrocortical conditioned reflexes].
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Conditioning, Classical↗
[Internal inhibition of electrocortical conditioned reflexes].
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Conditioning, Classical↗
[Participation of the head of the caudate nucleus of the dog in mechanisms of conditioned reflex postural reorganization].
On the model of instrumental defensive reflexes, components of conditioned postural reorganization were analyzed in 5 dogs before and after preliminary stimulation of the caudate nucleus head (CNH) of the contralateral (with respect to the active limb) hemisphere. The disturbance of normal function of the striatum caused by electric stimulation of CNH or by pathological changes elicited by a prolonged (during two-four years) CNH stimulation led to a significant change in the main mechanisms of posture reorganization: disturbances of the centre of gravity transfer and sharp rise of time of weight redistribution to the supporting limbs. Changes elicited by caudate pathology and by CNH stimulation went in the same direction. It is suggested that disturbances in the initiation of voluntary movement in striate pathology, are mainly caused by disturbances in posture initiation and reorganization, necessary for movement execution.
Animals↗
[Participation of neurons from symmetrical parts of the sensomotor cortex in conditioned reflex activity].
Spike activity of the symmetrical points of the sensorimotor cortex was studied in the course of formation and extinction of a defensive conditioned reflex in cats. In the process of pairings the impulse responses in the hemisphere contralateral to the paw stimulated with electric current (reinforcement) increased, and were inhibited in the ipsilateral hemisphere. Extinction of the reflex or functional switching off of the contralateral hemisphere restored the conditioned reactions of the ipsilateral hemisphere neurones. An assumption has been made that conditioned connections appear in both hemispheres, but under ordinary conditions the reactions are ensured by the dominating (in learning) hemisphere. If it is switched off, a duplicate conditioned connection appears in the other hemisphere, as one of the mechanisms providing for the reliability of manifestation of the conditioned relfex.
Animals↗
[Effect of the antioxidant ionol on the formation and retention of a defensive conditioned reflex during maximum physical exertion].
Administration of the synthetic antioxidant ionol to male Wistar rats prevents the disturbance of the conditioned reflexes during extreme physical load, induced by treadmill running. Protective action of ionol was marked by the improvement of the formation of the arising conditioned relations and their enforcement "till refusal" under maximal physical load. The possibility of antioxidant application to preventing the disturbances of the higher nervous activity is discussed.
Animals↗
Pavlov's position on the effects of decortication on conditional reflexes.
This paper examined D. Joravsky's (1989) hypothesis that I.P. Pavlov dogmatically refused to acknowledge that classical conditioning can be mediated by subcortical regions of the large cerebral hemispheres. Decortication literature from 1901 to 1936 was reviewed. The early studies available to Pavlov, who died in 1936, showed that decortication does not allow the establishment of new or retaining of old conditional reflexes (CRs). G.P. Zelenyĭ's later experiments(1930) suggested that the establishment of primitive CRs in decorticated dogs was possible. Pavlov never denied this possibility but cautioned that Zelenyĭ's experiments could have been methodologically flawed. Although Joravsky's original hypothesis on Pavlov's position on the relation between decortication and the establishment of CRs is by and large accepted, it must be stressed that Pavlov's theory of higher nervous activity was primarily concerned with the function of the brain in the higher organism's struggle for existence. Within this context the cortical, rather than subcortical, processes play the decisive role in the organism's adaptation to the changing external environment.
Animals↗
[Reproduction of electrographic correlates of a conditioned reflex after changes in the activity of the noradrenergic and dopaminergic systems].
On the model of shortly delayed defensive conditioned reflex in cats, it was shown in acute experiments that pharmacologically elicited change of NA system activity (clonidine, 0.2 and 1.5 mg/kg intravenously) and of DA system activity (apomorphine, 3 mg/kg intravenously) leads to a definite manifestation of electrographic correlates of memory trace, i.e. of conditioned evoked potential (EP) in examined brain structures, as well as of conditioned neurographic response (CNR) and conditioned skin-galvanic reaction (SGR). The increase of the NA system activity causes a rise of the number of conditioned EPs in the reticular formation, hippocampus and preoptic area along with an enhancement of CNR reproduction. The increase of the DA system activity contributes to the appearance of conditioned EPs in the hippocampus, amygdalar complex and central gray matter, together with an enhancement of the reproduction of conditioned SGR.
Animals↗
[Conditioned reflexes in relation to temporal intervals].
The paper outlines the results of experiments on twelve rats aimed at studying conditioned reflexes of discrimination of both absolute and relative characteristics of time intervals (30 and 180; 10 and 90; 5 and 45; 5 and 40; 5 and 35; 5 and 30 sec). The data obtained are discussed in the light of I.P. Pavlov's hypothesis regarding the physiological mechanism of conditioning to time.
Animals↗
Microelectrode analysis of the cellular mechanisms of conditioned reflex in rabbits.
Spikes and postsynaptic potentials (PSPs) were recorded in the sensorimotor cortex of awake rabbits. (1) A cellular analog of cortico-cortical conditioned reflex (CR) was studied. Direct cortical stimulation of a remote point (conditional stimulus - CS) was paired with the stimulation near the microelectrode insertion (unconditional stimulus - UCS). The most neurons showed response facilitation when short intertrial intervals and strong UCS were used. These changes were short-lasting (up to 30 s) and were explained by posttetanic potentiation. Of 21 units tested with long (7 to 120 s) intertrial intervals, 9 showed significant response modification of longer duration. (2) The analog of cortico-cortical CR was modified using stimulation of homolateral cortex as the CS. The UCS was complimented by lateral hypothalamic reinforcement (LHR) in instrumental or classical paradigm. Of 37 units tested, 5 showed an increase in the probability of short-latency ( less than 25 ms) spike. (3) Extracellular activity of 17 neurons was followed through the entire cycle of elaboration and extinction of a "local conditioned startle response" established by pairing click CS with cortical UCS and LHR. Responses of 7 neurons showed significant modifications. The latency distributions of averaged PSPs were compared for naive (N), conditioned (C) and extinguished (E) states. Latencies in N and E groups were similar but were different from those in C group. Of 41 C group neurons, 26 responded at a latency of less than 17 ms; and 9 responded after less than or equal to 7 ms. A pathway for this simple CR may pass through the cortex. Thus PSP changes were observed in all models. Augmentation of short-latency EPSPs support the idea that an increase in efficacy of excitatory synapses underlies the conditioning. Interneuronal excitatory connections within the sensorimotor cortex are, presumably changed during elaboration of simplest motor CRs. These connections can be analyzed with intracellular recordings triggered by spikes of a neighbouring neuron.
Animals↗
[Hippocampal neuronal activity in the switching of heterogeneous classical conditioned reflexes].
The impulsive activity of hippocampal neurons during the elaboration and specialisation of switching of the alimentary and defensive classical conditioned reflexes has been studied. The associative changes of the phasic and tonic neurons activity have been shown to be the neurophysiological background of the tonic and phasic mechanisms ensuring the conditioned switching. The differences between the tonic activity and the neuron response to the conditioned stimulus during different conditioned activity have been established. The difference of the neuronal activity to the conditioned stimulus during the change of its signal meaning is due to a great extend of the tonic activity. Motivation is supposed to play a leading role in the changing of the neurons activity under the conditioned switching.
Animals↗
The influence of experimental neurosis on the conditional reflexes and the content of blood catecholamines and acetylcholine in dogs.
Using experimental neurosis as a model, we investigated the mode of adaptive behavior, conditional reflexes and the blood level of neuromediators in four dogs placed in certain versus uncertain conditions in a Pavlovian laboratory. The research consisted of a two year training program with predictable (ordered partial reinforcement) followed by unpredictable (probabilistic reinforcement) situations. As a result, there was a decline in the acetylcholine as compared to a rise of catecholamine levels of the peripheral blood of some of these dogs. There were varied autonomic responses indicating a possible individual response specificity. In one dog, there was a disappearance of motor defense reflexes. The results support the hypothesis that probabilistic reinforcement following ordered partial reinforcement contributed to the dogs' neurotic disintegration, i.e., uncertainty is a cause of neurotic development.
Acetylcholine↗
[Conditioned reflex mechanism in the hypothalamic regulation of diuresis].
In chronic experiments on dogs with urethrae brought out to the skin of the abdomen and electrodes implanted in the hypothalamus, the possibility was studied of the involvement of a conditioned component in hypothalamic control of the kidneys activity under a direct action of electric current on a hypothalamus. The beat of a metronome and the experimental surroundings served as a conditioned stimulus, stimulation of the hypothalamus was used as an unconditioned one, and diuresis -- as a manifestation of the conditioned reflex. It was found that the conditioned mechanism is also involved in the complex mechanism of hypothalamic control of kidney activity. Such conditioned changes of diuresis may be effected in different functional states of hypothalamic nuclei.
Animals↗
Spatial-temporal organization of the functions of cortical neurons in a conditioned reflex to time.
The impulse activity of neurons in the motor cortex of cats during the development of a conditioned food-procuring reflex in relation to a time interval of 2 min (CRT) was analyzed. It was demonstrated, by comparing the behavioral and neurophysiological correlates of the formation of the conditioned food-procuring reaction, that its formation is accompanied by extremely complex systemic transformations which are different for neuronal micro- and macrostructures. The systemic processes in the micro- and macrostructures differed with respect to the specific characteristics of spatial distribution, and with respect to the number, strength, and stability of the manifestation of the functional connections. The capacity of the neurons for functional orientation even at the initial levels of the formation of the reaction, an increase in the per cent of incidence of functional connections in the second half of the conditioned reflex interval, and the substantial destabilization of all neuronal units at the last, highest level of formation of the conditioned reflex food-procuring reaction were common to the micro- and macrostructures in this form of learning.
Animals↗
[Protein synthesis-dependent reactivation of environmental conditioned reflex in terrestrial snails].
We investigated influence of anisomycine injection on reconsolidation of contextual memory after development of environmental conditioned reflex in terrestrial snail Helix. Testing the amplitude of behavioral reactions (tentacle withdrawal) in response to standard tactile stimulation of the skin in two contexts: a) when the snail was fixed by the shell and was moving on the surface of the ball floating in water, or b) was moving on the flat surface of glass terrarium, has shown no difference in response amplitudes. After a session of electric shocks (5 days) in one context only (ball) the associative learning was clearly observed as the significant difference of response amplitudes in two contexts. On the other day following testing was performed a session of "reminding", immediately after which the snails were injected by anisomycine (control snails were injected by saline solution). Testing has shown that injection of anisomycine led to impairment of the context conditioning. Results suggest that the mechanisms of consolidation of new memory and memory reconsolidation after retrieval are not identical.
Animals↗
[The interaction of the dominant and the conditioned reflex in the dynamics of the generalization phenomenon].
In dogs the generalization reaction to the stimuli of the same modality was observed with equal intensity both at the early and late stages of conditioning, while no generalization was observed to stimuli of different modalities. With increase in the level of the alimentary motivation the generalization reaction began to be recorded to stimuli of different modality. Thus, the spread and intensity of generalization depends on the strength of motivation. The persistence of generalization suggests that the dominant which underlies the generalization phenomenon is retained for a long time and can exist in parallel with the stable conditioned reflex.
Animals↗
[Motor alimentary conditioned reflexes and delayed reactions in dogs following destruction of the caudate nucleus].
The characteristics of formation and achievement of motor conditioned reactions were studied in seventeen dogs before and after the lesion of head or body of the caudate nucleus. It has been shown that the degree of higher nervous activity disturbances depends on the localization of injuries in the nucleus, and on the complexity of the tests used. The caudate nucleus exerts a modulating effect on the parameters of motor conditioned reflexes and takes a direct part in the structure of delayed reflexes. Lesion of the caudate nucleus body is attended with more serious disturbances of higher nervous activity than lesion of its head.
Animals↗
[Possibilities of regulating of immunologic reactions by means of conditioned reflex].
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Antibodies↗