PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “REFLEX, CONDITIONED”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 73 records · Page 4Linked to original sources
PubMedDate not supplied

[Elaboration of conditioned reflexes in dogs grown under conditions of partial intraspecies isolation].

New data are presented on the influence of relationships with representatives of the same species at early stages of ontogenesis on the higher nervous activity of adult dogs. It has been found that dogs raised up to one year with their coevals differ considerably less from the control dogs by the speed of elaboration and stability of complex conditioned reflexes than those raised in complete isolation beginning with the age of three months.

Animals↗
PubMedDate not supplied

[Effect of piracetam on the conditional reflex memory under probable reinforcement conditions].

The effect of piracetam on the development of a two-link system of feed-procuring conditioned reflexes was studied in rats with probability reinforcement. The experiments showed that piracetam improves both the current learning process and the memory track (previous experience) reproduction. In addition, the drug decreases the role of the probabilic character of reinforcement, thus facilitating the synthesis of two reflexes in a united functional complex.

Animals↗
PubMedDate not supplied

[The vegetative component of a conditioned reflex].

Defensive and alimentary conditioned reflexes were studied on normal cats and cats with neural isolation of the neocortex. The cardiac component of the conditioned reflexes is elaborated in decorticated animals at a similar rate and is as steady as in normal cats. Motor conditioned reactions in decorticated cats are difficult to elaborate. Both in normal and decorticated cats unconditioned pain stimulation evokes tachycardia, while a conditioned signal, paired with this unconditioned stimulus, produces bradicardia. Ban assumption has been made that the primary conditioned reaction consists in the appearance of a certain emotional state which changes the cardiac rhythm in a typical way.

Animals↗
PubMedDate not supplied

[Statistical analysis of interneuronal functional connections during conditioned reflex elaboration].

A milk conditioned reflex to a low frequency electrical stimulation of the visual pathways was elaborated in cats. Multineuronal activity in the visual and sensorimotor cortical areas was recorded in the chronic experiment. Statistical analysis of interneuronal intraanalyser and interanalyzer connections was made by constructing crosscorrelograms on the "Plurimat-C" computer. Comparison of the results of the interneuronal interaction in untrained and trained cats has shown an increase of one-way and two-way connections of both the intraanalyser and interanalyser types. Neurones with medium amplitude spikes changed their net properties more than other units acquiring ingoing and outgoing connections in both studied areas of the learned animals. Acquisition was achieved in all the neurones mainly due to increased number of connections from the sensorimotor analyser to the visual one. The problems of formation of backward conditioned connections and "local" conditioned reflex are discussed.

Animals↗
PubMedDate not supplied

[Characteristics of the systemic organization of the cortical neurons in various forms of the manifestation of the conditioned reflex to time].

Conditioned food-procuring reflex to time (2 minutes interval) was elaborated in cats. By the method of cross-correlative analysis the combined neurones activity in microareas and between microareas of the motor cortex was compared at various forms of conditioned reflex manifestation. Three types of reactions were considered: A--decrease of respiratory movements amplitude towards the end of the studied interval between reinforcement; B--increase of the amplitude; C--food-procuring paw movement a few seconds before the reinforcement. All three forms of the conditioned reflex to time differed from each other by the level of increase of functional connections number by the moment of the reinforcing stimulus action, and also to a greater extent by the frequency of occurrence of intervals in which the sum of neuronal connections in all simultaneously recorded microareas was greater in the "active" phase than in the "inactive" one. These parameters did not always correlate with the change of impulses frequency of separate neurones which occurred considerably more seldom. All the observed changes were manifest significantly more often when the animals performed the instrumental food-procuring movement than during changes of only the respiratory movements amplitude.

Animals↗
PubMed2005

Dopaminergic modulation of spike activity in sensorimotor cortex neurons in a conditioned reflex.

Changes in the spike conditioned reflex reactions of sensorimotor cortex neurons during microiontophoretic application of agonists and antagonists of glutamatergic and GABAergic transmission and their modulation by dopamine were studied. A paradoxical reaction is described, consisting of facilitation of spike responses evoked by antagonists of ionotropic glutamate transmission, which was blocked by GABA. This is evidence for the active involvement of inhibition in organizing the excitatory responses of neurons in the conditioned reflex. Application of the metabotropic glutamate transmission antagonist MCPG was accompanied by sharp suppression of the baseline and evoked activity of cortical neurons, along with increases in the latency of spike responses and conditioned reflex movement. Dopamine was found to reverse the effect of blocking metabotropic glutamate receptors and to normalize neuron activity, which is evidence for the stabilizing role of dopamine in the functioning of neocortical neurons.

Action Potentials↗
PubMedDate not supplied

[Interrelation between signal and reinforcing stimuli at the cellular level during extinction of motor conditioned reflexes].

Comparative analysis of extinction of neuronal activation conditioned reactions in the motor cortex, the ventromedial and perifornical hypothalamic nuclei attest that the connection between the signal and reinforcing components of pairings in these structures of alert rabbits is more stable in defensive conditioned reflexes than in conditioned reflexes to time. A more stable connection between two components is established during conditioning in neurones of the motor cortex and the perifornical nucleus, and a less stable one at the level of the hypothalamic ventromedial nucleus and the medial geniculate body. In conditioned reflex to time a more stable connection has been detected in neurones of the motor cortex, the medial geniculate body and the perifornical nucleus, a less stable connection in the neurones of the hypothalamic ventromedial nucleus.

Animals↗
PubMedDate not supplied

[Conditioned reflexes to the ratio of time intervals].

Conditioned reflexes to relation of temporal intervals, as a specific variety of reflexes to stimuli ratios, were studied in rats during alternation of two homogeneous trace stimuli with their separate reinforcement; the stimuli were addressed to one analyser, but were of different duration. Formation of conditioned reflexes to the ratio of temporal intervals began in rats after eleven sessions (106 pairings) on the average. The total duration of the whole process of formation up to stabilization of the reflex varied from 20 to 40 sessions (31 on the average), or from 200 to 394 pairings (308 on the average). The process of formation was the longer the less the ratio between the compared intervals (of a longer to a shorter one). The precision of the formed conditioned reflex to the ratio of temporal intervals (as expressed in the probability of correct reactions) amounted to 0.71% on the average. The experimental data may be satisfactorily explained in the light of concepts of Pavlovian school on the physiological mechanism of conditioned reflexes to stimuli ratios.

Animals↗
PubMed2001

Time course of H-reflex conditioning in the rat.

This study sought to define the course of operantly conditioned change in the rat soleus H-reflex and to determine whether, like H-reflex conditioning and spinal stretch reflex conditioning in the monkey, it develops in distinct phases. Data from 33 rats in which the right soleus H-reflex was trained up (i.e. HRup mode) and 38 in which it was trained down (i.e. HRdown mode) were averaged to define the courses of H-reflex increase and decrease. In HRup rats, the H-reflex showed a large phase I increase within the first 2 days followed by gradual phase II increase that continued for weeks. In HRdown rats, the H-reflex appeared to show a small phase I decrease and then showed a gradual phase II decrease over weeks. In combination with other recent work, the data suggest that H-reflex conditioning begins with a rapid mode-appropriate alteration in corticospinal tract influence over the spinal arc of the H-reflex, which causes phase I change, and that the continuation of this altered influence induces gradual spinal cord plasticity that is responsible for phase II change. The results further establish the similarity of H-reflex conditioning in primates and rats. Thus, they encourage efforts to produce a single coherent model of the phenomenon based on data from the two species and indicate the potential clinical relevance of the rat data.

Afferent Pathways↗
PubMedDate not supplied

[Mechanism of participation of neostriate nuclei in the organization of a conditioned reflex].

Formation and manifestation of classical and instrumental conditioned reflexes were studied in dogs under the action of electrical stimulation of the caudate nucleus and the putamen or after their electrolytic ablation. The extent of higher nervous activity changes depended on the localization of the electrodes in the nuclei and on the complexity of the tests used. Ablation of the caudate nucleus body elicited graver and longer disturbances in the system of conditioned reflexes than that of the head. Under the action of the neostriate nuclei delayed reactions changed to a greater extent than simple forms of conditioned reflexes. Proceeding from the data obtained, it has been assumed that the mechanism of neostriate influences on conditioned reflexes dependes on their comparatory function, the mechanism of comparing cortical and subcortical impulses at the striate level.

Animals↗
PubMedDate not supplied

[Significance of the relative position in space of associated stimuli for formation and performance of motor conditioned reflexes].

In experiments on cats the rate of formation of conditioned reflexes to sound (running to the feeding trough) depended on the spatial interrelations of the paired stimuli: the closer the source of the conditioned signal to the feeding trough, the sooner the formation of the conditioned reflex. It has been assumed that during formation of a conditioned reflex the closing of connection between conditioned and unconditioned stimuli is also attended with the closing of connection between the spatial parameters of the paired stimuli. Experiments with inactivation through cold of the temporal area (cortical representation of the vestibular system) of one hemisphere have shown that such a connection is formed in central parts of the vestibular analyser. When the conditioned reflex is elaborated to one feeding trough, the connection is duplicated by both hemispheres; in reflexes to two feeding troughs (i.e. spatial choice) such connections are lateralized in each hemisphere.

Animals↗