Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CONDITIONED REFLEX”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

[Formation of a defensive conditioned reflex to an acoustic stimulus in rabbits after early visual deprivation].

The formation of a defensive conditioned reflex to sound has been studied in rabbits raised from birth up to 30 days of life in dark. It was shown that, as compared with control animals of the same age, elaboration of reflex to sound takes place in them in shorter times periods and with less pairings. This corresponds to changes in electrographic manifestations of conditioning: increased amplitude and reduced peak latency of evoked potentials to acoustic stimuli in the auditory and sensorimotor cortical zones. The data obtained testify to enahcned functional activity of the auditory cortex, apparently due to a compensatory enhancement of impulse activity coming from the intact receptors of the auditory apparatus. It has been assumed that the observed functional changes appearing in the cortical end of the signal analyser (auditory zone); in response to sound, following visual deprivation, are a consequence of an early nature training of synaptic structures with regard to perceptionof impulses of acoustic modality.

Animals↗
PubMedDate not supplied

[The role of trace excitatory processes in the formation of conditioned reflexes to time].

I. P. Pavlov's hypothesis on the role of trace excitation in conditioning to time was verified by mathematical methods proceeding from experimental data on elaborating in rabbits a motor alimentary conditioned reflex to a four-minute interval of time. A connection has been established between the experimental characteristics of formation of a reflex to time and some parameters of the presumed dynamics of trace excitation. The analysis helped to establish the shortest and longest intervals to which a reflex to time can be elaborated by the mechanism of trace reflex, as well as the optimal interval to which it is elaborated more easily. The experimental results so obtained are a significant corroboration to the correctness of the Pavlov hypothesis.

Animals↗
PubMedDate not supplied

Participation of beta-endorphin in the regulation of conditioned reflex activity of cats.

The role of beta-endorphin in the regulation of conditioned instrumental food-procuring reactions and more complex forms of nervous activity such as reflexes of choice of the side of reinforcement was studied in cats. It was established that the subcutaneous injection of small doses of beta-endorphin (10 micrograms/kg, 15 x 10(-6) micrograms/kg) exerts a facilitatory nonspecialized effect on positive and negative food-procuring conditioned reflexes that has an overall adaptive character overall. The influence of the same doses of beta-endorphin on conditioned reflexes of choice is more complex in character, depending upon the initial level of conditioned reflex activity and on the typological features of the experimental animals. A possible mechanism of the influence of beta-endorphin on higher nervous activity is discussed.

Animals↗
PubMed1974

Hippocampal electrical activity and different types of conditioned reflexes in dogs.

Changes in hippocampal activity and heart rate were studied in dogs during elaboration of defensive and alimentary conditioned reflexes and switching-over between different types of reinforcement. Conditional stimuli enhanced synchronization and increased frequency of theta wave trains in hippocampal electrical activity. Parallelly to emotional tension of the dogs a significant rise in amplitude of integrated theta rhythm appeared. An increase in the positive correlation between the changes in amplitude of integrated theta rhythm and in heart rate shows that the hippocampal theta rhythm may be used as a correlate of emotional tension. Changes in hippocampal electrical activity in the early stages of formation of conditioned connections and throughout the experiment with conditioned "switching-over" suggest that emotional tension arises under conditions of pragmatic uncertainty when the animal does not have sufficient information for the organization of adaptive reactions. Mom marked changes in heart rate and in amplitude of hippocampal theta rhythm during the elaboration of defensive CRs compared with those observed during the development of response eliminating nociceptive stimulation of partner, suggest that the magnitude of emotional tension depends on the conditioned excitation underlying the response being elaborated.

Animals↗
PubMed1974

Precise instrumental conditioned reflexes and the role of different sensory modalities in their execution in dogs.

Elaboration of an instrumental reaction involving conditioned rearrangement of innate motor coordination takes a long time to attain in dogs. Particular difficulties are encountered in the execution of conditioned movement when painful stimulation evokes an inborn response opposite to the conditioned one. Exclusion of visual control of performance selectively impairs the phase of searching for the "safety zone" by the animal, whereas the ability to maintain the limb in a constant position for a long time and to carry out its correct readjustments was not affected. Exclusion of afferents from the joint led to profound and irreversible motor disturbances: along with considerable impairment of the ability to maintain the limb at a given height. Also affected were searching for the "safety zone" and the ability to carry out prompt and correct adjustments upon exposure to painful stimuli. As a result, motor reactions were accompanied by a large number of shocks when the "safety zone" was wide and could not be carried out at all when it was narrow. Forcing the animals into the unusual posture strongly disrupted the elaborated reactions: the animals were no longer able to find the "safety zone" either during the isolated action of the signal or during painful stimulation. The observed disturbances tended to progress and gradually led to the derangement of the motor habit, up to complete dropping out of the conditioned reflex component.

Animals↗
PubMedDate not supplied

[Functional organization of limbic brain structures during conditioned reflex activity in the dog].

In experiments on 3 dogs it was shown that instrumental defensive conditioned reflex (CR) to electrical stimulation of the hippocampus is generalized within the limbic system (LS). The rate of generalization depended on the place of testing stimuli in LS. Stimulation of the medial parts of LS at the stage of stabilized initial reflex did not produce the generalized CRs, while they appeared distinctly in response to stimulation of the lateral parts of LS. In the process of elaboration of heterogeneous CRs (defensive and alimentary) to electrical stimulation of the hippocampus, generalized conditioned reactions from some brain structures appeared in both situations to the same degree while from other structures--with considerable differences. These data point to a possible participation in the genesis of the generalized CRs both of signal and reinforcing brain mechanisms.

Amygdala↗