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P Ia Kravtsov

Publications and source records attributed to P Ia Kravtsov.

13 recordsLinked to original sources
PubMed1999

[Convergence studies of hypothalamic neurons].

In this study has been reveibed the peculiarities of convergence of afferent cortical inputs to the hypothalamic neurons. Single and the serial stimulation of phylogenetically distinct cortical areas (proreal cortex (field 8), cingular cortex (field 24), pyriform lobule (periamygdala cortex), and hippocampus (CA3) were used. We have established two main focuses of expressed convergence of signals from the above mentioned cortical areas. First of them was located in the lateral hypothalamus nucleus, second--in the centromedial hypothalamus nucleus. Single cortical stimulation was found to excite majority of hypothalamus neurons. Expressed prevalence of inhibitory responses over excitatory ones were found in case of serial stimulation application. This functional organisation of the hypothalamic nucleus allow to propose tonic character of the cortical influences due to serial stimulation and the eventual character of these influences due to single stimulation.

Afferent Pathways↗
PubMed1992

[Sources of cortical, hypothalamic and spinal serotoninergic projections: topical organization in the dorsal Raphe nucleus].

Distribution of primuline, fast blue, fluoro-gold and nuclear yellow-labelled monoamine-containing cells in periventricular gray and dorsolateral tegmentum (including locus coeruleus) was studied in the rat after injection of these fluorochromes into the frontal cortex, hypothalamus and spinal cord. Combination of monoamine fluorescence method and retrograde cell-labelling was used. Two big groups of serotonin-positive cells projecting into the upper thoracic spinal segments were found in dorsomedial zone of the dorsal raphe. Part of these units also had divergent axon projections to the frontal cortex. Such cellular arrangement allows a supposition that analgetic effects of dorsal raphe stimulation can be partially based on the direct participation of this structure in the descending control at the spinal level. Neurones, sources of cortical projections are intermingled with the cells projecting to the hypothalamus but some topical differentiation can be distinguished. Neurotransmitter and neuroregulatory roles of separate cortical and hypothalamic projections of serotonin-containing neurons of the dorsal raphe cells is discussed.

Animals↗
PubMed1991

[Reactions of neurons of the preoptic area in the presence of serial cortical stimuli].

Evoked potentials (EPs) and neuronal responses of the medial (MPO) and lateral (LPO) preoptic region (RPO) and adjacent areas of the anterior hypothalamus to serial (6-300 s) stimulation of the prefrontal (area 8), cingulum (area 24), periamygdaloideus (RPA) cortex and hippocampus (field CA3) were studied on experimental cats anesthetized by ketamine. Cortical areas were selected according to their evolutionary status. Responses of preoptic neurons to serial stimulation were grouped into four main types: excitatory, inhibitory, excitatory on-off-effect and inhibitory on-off-effect. No pronounced changes in the patterns of response reactions were found when frequency of the stimuli increased, only intensity of the reactions changed. Neurons responding to serial cortical stimulation were located mainly in the central part of the MPO and in the basal part of the LPO. These areas of the RPO contained neurons with the most pronounced convergence of different cortical stimuli to the same cell. In serial cortical stimulation inhibitory reactions developed more frequently than excitatory ones (ratio 3.4:1). A gradient of inhibitory reactions to stimulation of different cortical areas was observed while comparing them in terms of evolution from new to old structures. Prevalence of inhibitory responses over excitatory ones was minimal (ratio 1.7:1), when the neocortex (area 8) was stimulated and it was more pronounced (ratio 1.9:1) during stimulation of the evolutionary intermediate cortex (area 24). That prevalence was still more significant (ratio 4.5:1) in case of paleocortical (RPA) stimulation and it was the most pronounced (ratio 10.2:1) during stimulation of the archicortex (hippocampus).

Animals↗
PubMed1990

[An organizational analysis of the neurons forming the descending cortico-hypothalamic pathways].

Quantitative assessment of spatial organization of cortical neurons forming descending fibre systems and hypothalamic structures has been made using technique of retrograde axonal transport of horseradish peroxidase. Heterogeneity of cortico-hypothalamic bonds is determined: the prefrontal cortex exerts a more pronounced effect on the hypothalamus as compared with other cortical areas of the limbic brain. Cortico-hypothalamic neurons form neuronal groups on different frontal levels of the prefrontal cortex and convolution of the cingulum, a form and orientation of the group being determined by the topography of dominating axonal systems running to the hypothalamus. There are various forms of cell associations in the frames of neuronal populations. Ensemble groupings of neurons may underlie the principle of organization of direct cortico-hypothalamic ways.

Afferent Pathways↗
PubMed1978

[Responses of neurons of hypothalamic nuclei to stimulation of the frontobasal regions of the neocortex].

Neuronal responses of different hypothalamic nuclei to frontobasal cerebral cortex (proreal, posterior orbital, basal and temporal regions) were studied in acute experiments on cats narcotized by membutal mixed with chloraloze. Neurons which could be activated antidromically during stimulation of another region were recorded. On the basis of their response a number of neuronal chains (circles) functioning in forebrain was distinguished. The first chain is orbital gyrus--preoptical zone--proreal gyrus. The second chain has the same cortical components as the first one, but switching over in the hypothalamus takes place in the region of mamillary bodies. The third chain is basal temporal cortex--lateral hypothalamus--prefrontal cortex.

Animals↗
PubMed1977

[Responses of neurons of the medial group of thalamic nuclei to stimulation of the fronto-basal portions of the neocortex].

Neuronal and focal responses of medial thalamic nuclei (mediodorsal, central lateral, parecentral, centrum medianum, parafascicular) to stimulation of frontobasal cerebral cortex (proreal, posterior orbital, basal temporal regions) were studied in acute experiments on cats narcotized by nembutal mixed with chloralose. Proceeding from the data on the number of neurons responding to cortical stimulation and on the duration of the response latent period, three functionally heterogeneous sections of medial nuclei were distinguished: the microcellular and magnocellular regions of the mediodorsal nucleus, and the intralaminar nuclei with the parafascicular complex. Neurons were recorded which could be activated antidromically during stimulation of another region. On this basis a suggestion is made on the integrating function of medial nuclei providing unification of the frontobasal regions of the neocortex.

Animals↗
PubMed1976

[Electrophysiologic study of cortico-hypothalamic interrelationships in cats].

In acute experiments on cats anesthetized with nembutal and chloralose the projections of different parts of orbito-frontal cortex, basal temporal cortex and hippocampus to hypothalamic nuclei were studied by focal potential recording. It was found that the proreal gyrus has local projections into the latero-dorsal parts of the preoptical region, rostral parts of the forebrain medial bundle, lateral and posterior hypothalamus with mammilary bodies. The orbital gyrus is projected mainly into latero-dorsal parts of the forebrain medial bundle, latero-ventral part of the preoptical region, and the region of lateral and latero-dorsal hypothalamic nuclei. Projections from the orbital gyrus are of a relatively diffuse character. The basal temporal cortex has diffuse projections into the central part of the preoptical region, latero-ventral part of the forebrain medial bundle and lateral mammilary body. No pronounced foci were observed in the hypothalamic structures during stimulation of the hyppocampus, but diffuse projections were found into ventral parts of the preoptical region and ventral regions of the forebrain medial bundle as well as into lateral hypothalamus and lateral mammilary nucleus.

Animals↗
PubMedDate not supplied

[Dynamics of the indices of the prostacyclin-thromboxane system in adolescents with hypotensive type vegetovascular dysfunction exposed to hyperbaric oxygenation].

As many as 185 juveniles aged between 11 to 14 years presenting with hypotensive type vegetovascular dysfunction have been examined to study the time-related changes in the blood content of prostacyclin and tromboxane under conditions of hyperbaric oxygenation. The control group copmrised 69 essentially healthy juvenile subjects the same age as those with dysfunction. Hyperbaric oxygenation has had a normalizing effect on indices for the prostacyclin-tromboxane system in those juveniles presenting with hypotensive type vegetovascular dysfunction, which fact can be explained by a drop in tenseness of mechanisms of the vegetative imbalance compensation.

Adolescent↗
PubMedDate not supplied

[An assessment of the manifestation of the functional connections between brain structures].

Responses of hypothalamic neurons to single (1/s, 20 impulses) stimulation of the prefrontal (area 8), cingulum (area 24), periamygdaloideus (RPA) cortex and hippocampus (field CA3) were studied on experimental cats anesthetized with ketamine. The routine elaborated for IBM PC/AT 386 provided: 1) selection of such neurone reaction with the latent period variation less than its length per the set value (5-20%); 2) selection of repeated neurone reactions with the same variability of latent periods from 20 cortical stimuli; 3) ranging of neurone reactions according to these indices. Quantitative estimation of the priority ranges made it possible to determine the profundity of the functional relations between the cerebral structures.

Animals↗