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Results for “CONDITIONED REFLEX”

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At least 253 records · Page 14Linked to original sources
PubMed1982

[Adrenal cortical function in elaborating a passive avoidance conditioned reflex in rats adapted to experimental conditions].

Fluorometry was used to determine the content of 11-hydroxycorticosteroids (11-HCS) in the blood plasma of 2-month-old male rats in the course of passive avoidance learning by means of single electrocutaneous irritation (ECI) of the limbs. Pre-exposure of the animals for 7 days to experimental environment (over 3 min daily) led to a distinct reduction of the basal content of 11-HCS which returned to the initial level after adaptation discontinuance. One day after ECI the content of 11-HCS in rats which learned passive avoidance, was appreciably lower as compared to that in the animals which failed to learn the behavioral task. Five days after ECI the differences in the content of the corticosteroids in the animals of the two groups were little pronounced. It appears that while using passive avoidance as a long-term memory model, account should be taken of both the behavioral and emotional responses.

11-Hydroxycorticosteroids↗
PubMedDate not supplied

[Effect of acute melipramine administration on motor activity and defensive conditioned reflexes of passive and active avoidance in rats].

The administration of threecyclic antidepressant melipramine to Wistar rats (15 mg/kg, intraperitonaly, 2 h before of experiments) increases time of an "open field" centre leaving. Thus melipramine does not influence horizontal and vertical activity, and also the number of bolus. At the development of a passive avoidance conditioned reflex melipramine significantly slows down realization of a unconditional mink reflex by untrained rats, increasing the latency of call in a dark compartment of the chamber. After training significant deterioration of a reflex reproduction is observed. At research of a defensive conditioned reflex of active avoidance melipramine worsens both development and reproduction of a reflex. The comparative analysis of the literary data of imipramine action on uptake of serotonine and noradrenaline and the analysis of the literary data on a role of these systems in the processes of learning and memory allows to suggest, that the effect of melipramine is connected mainly to amplification activity of serotoninergic system of a brain. It is supposed, that acute administration of melipramine creates emotionally negative state, worsens processes of learning and memory, strengthening mainly activity of a brain serotoninergic system. It specifies that serotoninergic system of a brain is system of punishment. Its activation interferes with formation and consolidation of connections between conditional and unconditional irritation.

Animals↗
PubMedDate not supplied

[Evoked potentials of neocortical projection areas during short-delay defensive instrumental conditioned reflexes in dogs].

The elaboration of a defensive instrumental conditioned reflex with a short delay (only 1 s) to clicks (a series of 10 clicks, 0.9 c/s) leads to a considerable change in the pattern of EP in the auditory cortical area elicited by the first (conditioned) click of the series. A number of very late positive-negative oscillations appear, covering all the latency of the conditioned motor reaction (700-900 ms). In the somatosensory and motor cortical projections of the acting leg, the first click begins to elicit EPs synchroneously reproducing all components of the EP in the auditory cortex; this is considered as a manifestation of the functioning of the projections of the paired stimuli in one and the same rhythm.

Animals↗
PubMed1975

[Influence of the anterior and posterior hypothalamus on the conditioned reflex activity and delayed responses of lower simians].

In 4 adult monkeys, electrical stimulation of the anterior hypothalamus followed by subsidence in the animal and the ECoG synchronization evoked also an impairment of conditioned reflex activity and a decrease in the test performance during delayed responses. Strong stimulation of the posterior hypothalamus followed by emotional arousal and desynchronization in the ECoG, on the contrary, improved the conditioned reflex activity and increased the level of the test performance. The hypothalamus is then supposed to play a certain role in memory as an emotiogenic structure.

Animals↗
PubMed2003

The action of mexidol on the state of conditioned reflex activity after traumatic brain lesions.

It is demonstrated that even partial damage to the hippocampus is accompanied by impairments to counting time intervals lasting several months (1200-1500 presentations) without alteration of other complex conditioned reflex responses. After treatment with mexidol, which has a wide spectrum of actions, paticularly antioxidant. antihypoxic, and antistress, rats showed a normal process of acquisition of a conditioned reflex to time. Unlike animals of the control group, there was no prolonged period during which there was complete impairment of the mechanism for counting time intervals. Thanks to significant improvements in autonomic processes and emotional-motivational responses, experiments could use a large number of conditioned stimuli. For example, after brain trauma mexidol strengthened compensatory-restorative processes: animals showed accelerated recovery of impaired functions, with decreases in the rate of retrograde degeneration of brain areas directly connected to the damaged parts, phenomena such as Monakow diaschisis were not observed, and so on.

Algorithms↗
PubMedDate not supplied

The correlation between changes in synaptic efficiency and cellular excitability during the development of a conditioned reflex analog.

The calculation of the coefficient of correlation between changes in the direct (D) and monosynaptic (I) components of the pyramidal tract (PT) response made it possible to establish the presence of a positive linear association between conditioned reflex changes in synaptic efficiency and the shifts in cellular excitability observed at the same time. The coincidence of the maximal strength of this association with the greatest increase in cellular excitability which is dependent on the activation of motivatiogenic structures points to the role of these subcortical structures in the launching of intracellular reactions which leads to the formation of the overall molecular substrate which underlies interaction of membrane and synaptic mechanisms. The preceding of the greatest enhancement of synaptic efficiency by the maximal manifestation of the interaction attests to the contribution of this process to the manifestation of the principal mechanism of the conditioned reflex (CR).

Animals↗
PubMed1992

[Effect of T-activin on the formation of conditioned reflex and manifestations of unconditioned reflex of avoidance in August strain rats].

It has been revealed that intraperitoneal injection of T-activin (humoral factor of the thymus) to August rats leads to more rapid and stable conditioned reflex formation to a sound and to a decrease of avoidance time when electric current is given to a shuttle chamber. Furthermore, less amount of uneffective series in testing unconditioned avoidance is registered in the test animals. A positive T-activin effect on conditioned reflex formation and unconditioned reflex manifestation is probably connected with its ability to alter hippocampus functional parameters and (or) with anti-stressor properties of the preparation.

Adjuvants, Immunologic↗
PubMedDate not supplied

Role of dopaminoreactive systems of the cortex and the neostriatum in the organization of situational conditioned reflexes.

The results of experiments on dogs with dysfunction of the dopaminoreactive system of the brain suggest the nonidenticality of its different divisions (cortical, striatal, mesencephalic) in the organization of situational conditioned reflexes. It was demonstrated that the nigrostriatal system is involved to a greater degree in the spatial analysis of signals, while the mesocortical system is more involved in the analysis of their biological significance. The dopaminoreactive system of the caudate nucleus is associated to a greater degree with the realization of cognitive, while that of the putamen is associated with the realization of motor programs of situational conditioned reflexes. The thesis of the necessity of the coordinated functioning of the DA-reactive systems for the organization of goal-directed behavior is substantiated.

Acoustic Stimulation↗
PubMedDate not supplied

[The effect of removal of the frontal region of the brain on conditioned reflexes to time and available stimuli].

The experiments were made on six dogs by the motor alimentary technique. It has been shown that ablation of the frontal lobe (fields: F1; F2; F3; F4) does not eliminate previously elaborated conditioned reflexes to time, temporal differentiations and reversals. They were disturbed because of motor perseverance only during the first one to three months. A conditioned reflex to time and temporal differentiations are elaborated much slower in dogs with a preliminary lobectomy, as compared with intact animals. A conclusion is drawn that the frontal lobe is not directly involved in counting the time macrointervals.

Animals↗
PubMedDate not supplied

Reorganization of activity of neurons of orbital cortex during formation of classical second-order conditioned reflexes.

The reorganizations of the activity of neurons in the orbital cortex during the formation and realization of classical first- and second- order conditioned reflexes were studied in chronic experiments with eight dogs. An analysis of the histograms of the distribution of between-impulse intervals, poststimulus histograms, and the changes in the average discharge frequency showed that the responses of neurons to the presentation of a first-order or second-order conditioned signal (for a second-order reflex) undergo dynamic changes with the development and strengthening of conditioned connections. The pattern of impulse activity during the action of a conditioned signal approximates in form the pattern of discharges during the action of reinforcement. The data are discussed in light of E. A. Asratvan's concepts of the mechanism of formation of complex forms of conditioned reflexes.

Animals↗
PubMedDate not supplied

[Analysis of the process of learning in the formation of the conditioned reflex of avoidance in rats].

During acquisition of avoidance conditioned reflex (CR) in shuttle box by electric shock it is shown that the performance of that defence reaction is induced by the joint action of two factors: general arousal of animals and motivation. Motor activity of rats in an "open field", the number of short-latency (2s) and intersignal responses during formation of the avoidance CR are in index of the general arousal of rats. An artificial increase in the general arousal of animals by caffeine induces acceleration of CR performance. A constant level of the general arousal of rats is one of the reasons that oxytocin does not influence the rate and dynamics of the avoidance CR performance in rats.

Animals↗
PubMedDate not supplied

Modulation of the spike activity of neocortex neurons during a conditioned reflex.

Experiments were conducted on cats to study the effects of iontophoretic application of glutamate and a number of modulators on the spike activity of neurons in the sensorimotor cortex during a conditioned reflex. These studies showed that glutamate, as well as exerting a direct influence on neuron spike activity, also had a delayed facilitatory action lasting 10-20 min after iontophoresis was finished. Adrenomimetics were found to have a double modulatory effect on intracortical glutamate connections: inhibitory and facilitatory effects were mediated by beta1 and beta2 adrenoceptors respectively. Although dopamine, like glutamate, facilitated neuron spike activity during the period of application, the simultaneous facilitatory actions of glutamate and L-DOPA were accompanied by occlusion of spike activity, and simultaneous application of glutamate and haloperidol suppressed spike activity associated with the conditioned reflex response. Facilitation thus appears to show a significant level of dependence on metabotropic glutamate receptors which, like dopamine receptors, are linked to the intracellular medium via Gi proteins.

Animals↗
PubMed1984

Some aspects of conditioned reflex activity during sleep.

Acquisition, retrieval and extinction of instrumental alimentary reflexes during various types of sleep was studied in cats with metallic electrodes chronically implanted in different brain structures. The possible acquisition and extinction of a defensive conditioned reflex with the onset of paradoxical sleep (PS) serving as a conditioned signal and painful electrical stimulation of the skin as unconditioned was investigated. Results suggest that: (i) in the presence of a high food motivation the conditioned signals delivered during sleep cause the retrieval of previously acquired instrumental alimentary reflexes, and in PS the brain is capable of discriminating conditioned signals more accurately than during slow wave sleep, (ii) after a conditioned reaction to one of two conditioned signals is extinguished through non- reinforcement, the second signal remains effective, causing an instrumental alimentary reflex, (iii) the extinction of instrumental alimentary reflexes effected during sleep is not retained after the animal's awakening, whereas the extinction of a defensive conditioned reflex is retained, (iv) PS may serve as an endogenous conditioned signal during the acquisition of a defensive conditioned reflex. Thus motivational processes developing during PS are effective endogenous stimuli eliciting past experience dreams.

Animals↗
PubMedDate not supplied

[Temporal structure of the spike trains in the neuronal impulses of the visual and sensorimotor areas of the rabbit neocortex during conditioned reflex activity].

Conjugated spikes were singled out from successions of discharges of neurones in the rabbit's visual and sensorimotor neocortical areas acting in correlation. Their temporal structure was studied at intersignal intervals in transswitching of defensive positive and inhibitory conditioned reflexes and also in pseudoconditioning. The obtained results testify that conjugated discharges appeared for the most part periodically (in the average in 85% of fragments of unit activity). At positive and inhibitory conditioned reflexes, the frequency of periodical conjugated discharges belonged in most cases to the theta-rhythm range. At pseudoconditioning, periodical conjugated discharges were in the main of frequencies of delta-range (up to 4 Hz). The obtained results testify about a great significance of cortical neurones interaction in theta-range frequency at conditioned activity.

Action Potentials↗
PubMedDate not supplied

The influence of chronic activation and blockade of the dopamine- and enkephalinergic systems of the neostriatum on conditioned reflex behavior and dopamine metabolism in the rat nigrostriatal system.

The effects of daily injections, over the course of 14 days, of 45 micrograms of phenamine, 5 micrograms of haloperidol and naloxone, 15 micrograms of leu-enkephalin and its analog, a tetrapeptide, into the rostral neostriatum have been studied. The chronic stimulation of the dopaminergic system of the striatum induced facilitation of the realization of an active avoidance conditioned reflex, and stimulated exploratory stereotypy, while its blockade led to suppression of conditioned reflex activity against the background of a clearcut rigid akinetic syndrome. The microinjections of leu-enkephalin and naloxone did not substantially alter the behavior, but the injection of the tetrapeptide was accompanied by changes in behavior, with symptoms of catalepsy and hyperkinesia. Injections of phenamine and haloperidol were accompanied by a decrease in the content of dopamine in the striatum and an increase in the level of DOPAC; the injections of enkephalin and naloxone induced changes of the reverse order. The possible causes of the noncorrespondence of the behavioral and neurochemical shifts in the presence of a direct chronic pharmacological action on the mediator of the neostriatum.

3,4-Dihydroxyphenylacetic Acid↗