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Results for “CONDITIONED REFLEX”

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PubMedDate not supplied

[Conditioned reflex and electrical activities of the hippocampus during the random use of heterogeneous triggering stimuli].

In dogs with electrodes chronically implanted in the hippocampus, the conditioned activity, heart rate frequency and spectral characteristics of the hippocampal theta-rhythm were studied in conditions of irregular presentation after a preparatory stimulus now of alimentary and now of defensive triggering conditioned stimuli. It is shown that uncertainty of alimentary or defensive reinforcement is a stronger emotiogenic factor than the action of the triggering defensive conditioned stimulus. Changes in electrical hippocampal activity and autonomous activity depend, along with other factors, on forecasted volume of the forthcoming motor activity. The speed of instrumental conditioned reflexes formation correlates with the hippocampal theta-rhythm frequency, typical for the given animal.

Animals↗
PubMedDate not supplied

[Dynamics of conditioned reflex preservation in young and adult rats].

Experimental data are presented on the formation and retention during 24 hours of a motor alimentary conditioned reflex (MCR) in a T-maze, in rats 4--5 months and 1,5--2 months old. In adult rats the formation of MCR required a significantly smaller number of runs and less time, than in young ones. In young animals reflex retention is better as compared to adults. Traces of MCR change regularly throughout 24 hours in both animal groups which may be due to development of memory in several stages, in young animals this process being slower.

Age Factors↗
PubMedDate not supplied

[The characteristics of the spatial-temporal organization of the cortical potentials in the free-moving rabbit during training (a comparison of the stages in the generalization and specialization of the conditioned-reflex response)].

Analysis of successive topograms was applied to investigation of peculiarities of the spatio-temporal organization of cortical potentials of a rabbit at different stages of conditioning. Qualitative distinctions were shown between the stages in the character of regulation of the spatial synchronization (SS) related to variations in cortico-subcortical relations. Higher SS level at the stage of generalization changed for more complicated pattern of the spatio-temporal organization of cortical potentials. These complex spatio-temporal characteristics favoured facilitation of excitation spreading along the paths which provide specialization of the conditioned response under the action of the conditioned stimulus. Obtained results were correlated to specific membrane and synaptic modifications in the course of conditioning. The findings extend the notions of the cellular mechanisms which determine the features of the cortical SS at the stages of generalization and specialization of the conditioned reflex.

Animals↗
PubMed1973

Power spectra of cortical electric activity in the rabbit in relation to conditioned reflexes.

In chronic experiments on rabbits spectral and correlation characteristics of cerebral cortical potentials were computed to study the elaboration of a conditioned defense reflex. was found that the frequency spectra of the EEG are subject to consistent changes: a narrow-band frequency constantly developing in the theta range. During exposure to a positive conditioned stimulus, the maximum of this frequency increased relative to the pre-stimulus period and a maximal coherence of electrical processes was observed in a narrow theta range between the electrical processes of the cortical analyzers to which the conditional and unconditional stimuli were addressed. Different relationship was noted in the theta range during presentation of a differential or extinguishing stimuli: it became slightly slower than in the pre-stimulus period, and the coherence of the theta rhythms was less than maximal, remaining high at the other frequencies. It was concluded that the presence of highly coherent electrical processes in the theta range is important for the formation of conditioned reflex in the rabbit cerebral cortex. The processes of internal inhibition are characterized electrographically by disagreement of electrical processes in the theta range in respect to phase or frequency.

Animals↗
PubMedDate not supplied

[Effect of damage to the serotonin- and noradrenergic systems of the brain on alimentary and defensive conditioned reflexes in rats].

A study was made on 79 Wistar male rats of the influence of destruction of single nuclei in the brain serotonin- and noradrenergic systems on their learning with alimentary and pain reinforcements. Electrolytic lesion of the raphe dorsal and medial nuclei hindered the formation of alimentary conditioned reflexes, while facilitating the elaboration of a conditioned active avoidance reaction. Destruction of the locus coeruleus was attended with improved alimentary learning, while the elaboration of conditioned active avoidance reaction proved to be more difficult as compared with that in the control animals. A conclusion is drawn that the nature of the influence of local ablation of individual nuclei in the brain serotonin- and noradrenergic systems on animals' learning is determined by the emotional sign of the reinforcing stimulus.

Animals↗
PubMedDate not supplied

[Changes in conditioned reflex activity during adaptation of the rat to pressure-chamber and high-altitude hypoxia].

A group of rats with a stereotype of conditioned reflexes was preliminarily trained to hypoxia effects during 30 days (at the "altitude" of 6000 m, time of exhibition--from 10 to 60 min, for 18 days--only 60 min). Adaptive changes in the process of training consisted in a weakening of differentiation inhibition, partial amnesia of the conditioned reaction of active avoidance and appearance of phasic states (equalization and paradoxical phases) in the cerebral cortex. The following adaptation of hypoxia "trained" rats to new natural conditions of Alpine altitude (3200 m) proceeded favourably, without disturbance of differentiation inhibition and without phasic states. Rats without preliminary training to altitude chamber hypoxia, in mountains (3200 m) were subjected to moderate tension resulting in protective inhibition, partial amnesia and transient disturbance of differentiation inhibition.

Adaptation, Physiological↗
PubMed2004

[Effect of dopamine on activity of brain sensory-motor cortex neurons during conditioned reflex].

A changes of background and evoked activity of deep cortical layers neurons and latency of the movement in the response to the conditioned stimuli were investigated in cats chronical experiments during microelectrode iontophoretic local aplication of dopamine, its antagonists and antagonists ofglutamatergic and gabaergic transmission. It was shown, that application of dopamine and others synapticaly active substances near soma of pyramidal neurons moderately increased their background and evoked activity and did not sygnificantly change their latency. Application of dopamine antagonists sulpiride and SCH 23390 depressed the background and evoked impulse activity and increased the latency of neuronal reaction and conditioned movements. These effects were completely removed by the aplication of the same antagonists together with dopamine. Dopamine removed the depressing influence on the background and evoked impulse activity and latency of the conditioned reflexes evoked by application of antagonists of glutamate ionotropic and metabotropic transmission (AP-4 and MCPG). The same stabilized influences were evoked by the iontophoretic application of GABA antagonist bicuculline. It was concluded that effects of dopamine are connected with its local inhibitory influences on the inhibitory interneurons and their synaptic endings on soma of pyramidal neurons.

Action Potentials↗
PubMed2004

Cerebellar activation during leg withdrawal reflex conditioning: an fMRI study.

OBJECTIVE: The aim of the present study was to examine cerebellar areas related to conditioning of the nociceptive leg withdrawal reflex using event-related functional magnetic resonance imaging (fMRI). Because of the aversive nature of the unconditioned stimulus effects of accompanying fear conditioning were expected. METHODS: In 20 healthy adult subjects leg withdrawal reflex conditioning was performed using a standard delay protocol during MR-scanning. Electromyographic recordings from the anterior tibial and biceps femoris muscles were used to quantify conditioned responses. Fear-related changes of heart rate were assessed. RESULTS: In the group of all subjects a significant increase of cerebellar activation was found in the anterior and posterior vermis. In the group of subjects (n=9) who showed conditioned leg withdrawal responses cerebellar activation was more pronounced in parts of the anterior vermis, which correspond to the known leg representation. In the group of subjects (n=11) who did not develop conditioned responses cerebellar activation was more pronounced in the posterolateral hemispheres. Changes of heart rate, however, did not significantly differ between groups. CONCLUSIONS: Results suggest that areas within the anterior vermis are involved in conditioning of the leg withdrawal response. The present results, however, do not allow to differentiate between motor performance, learning or timing-related processes. Areas in the posterior vermis and cerebellar hemispheres may be related to concomitant fear conditioning. SIGNIFICANCE: Results of the present event-related fMRI study suggest involvement of the human cerebellum in conditioning of the nociceptive leg withdrawal response.

Adult↗
PubMed1989

[Stimulation of experimental conditioned reflex impotence and a new method of detecting an aphrodisic effect].

Ten original apparatuses were constructed to examine aphrodisiac effect. For the purpose conditioned reflex impotence was induced in white male mice in advance. Using the new method for establishment of the aphrodisiac effect the values of ED50 of the preparations Yohimbin, Testosteronum dipropionicum, Tribestan, Captogon, Coffeinum n. benzoicum and Imipramin were estimated. The new method allows to differentiate aphrodisiac effect from psychostimulating and antidepressive action. The advantages of the new method are: objectivity, adequacy to human pathology and does not require constant observation of the experiment.

Animals↗
PubMedDate not supplied

[Changes in the cholinosensitivity of sensomotor cortex neurons during conditioned reflex extinction].

Characteristics of neuronal responses of the sensorimotor cortex to ionophoretically administered neuromediators (acetylcholine, L-glutamate) were studied in rabbit in the course of extinction of conditioned defensive reflex. In the majority of neurones the extinction of the conditioned reflex is accompanied by a drop of cholinosensitivity. In a number of neurones the extinction of reflexes either does not change the reaction to acetylcholine, or enhances it. The analysis of these reactions permits to assume the existence of a group of neurones directly involved in the formation, fixation and storage of the temporary connection.

Acetylcholine↗
PubMedDate not supplied

[Responses of neurons of the associative parietal cortex during acute extinction restoration of a conditioned reflex].

The dynamics of spike neuronal activity in the parietal associative cortex was studied in the course of acute extinction and restoration of a conditioned reflex. Certain similarities have been found in neuronal firing during the reorganization of behavioral acts (transient processes in neuronal activity, general types of neuronal responses, etc.) The data obtained suggest the involvement of neurones of the parietal associative cortex in the processes related to the reorganization of behavioral acts, and the existence of common mechanisms of search for an optimal regime of neuronal assemblies functioning in different types of conditioned activity.

Animals↗
PubMed1995

Pavlov on the conditioned reflex method and its limitations.

Pavlov's aim was to use the salivary conditioning method to investigate the function of the brain of higher animals in their adaptation to the external environment. The salivary reflex, according to Pavlov, was of minor biological significance but a good indicator of the subtle changes in the brain under different experimental conditions. To account for conditioned reflex phenomena, Pavlov faced two alternatives: to offer an objective (physiological) or a subjective (psychological) explanation. In 1901, after a bitter conflict with his disciple A. T. Snarskiy, Pavlov chose the first alternative. During the next decades, Pavlov provided reasons for this decision: The physiological approach (a) avoids anthropomorphizing or speculations about the dogs' subjective experiences, and (b) permits the explanation of observed phenomena which the subjective method is not capable of doing. Pavlov realized that the conditioned reflex method has a limitation; it cannot be used in the study of human subjects because their thinking interferes with experimental results.

Conditioning, Classical↗