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Biomedical subjects

A G Poliakova

Publications and source records attributed to A G Poliakova.

At least 19 recordsLinked to original sources
PubMed1986

[Polysensory properties of the horizontal region of the diagonal bundle from the cat forebrain].

Sharply different wave forms and parameters of averaged evoked potentials (EP) in response to single visual and somatic stimuli were observed in the same points of the horizontal limb nucleus of the diagonal band (NDB) in cats under nembutal anesthesia. The existence of heterogenic EPs in NDB makes it possible to consider this part of the nucleus as a polysensory structure. Decreased EP latency, as compared to that in the neocortex, indicates that heterogenic impulses reach NDB by higher speed Ways than the cortex. The comparison of NDB EP refractory periods during paired stimulation of one or different sensory systems shows that polyvalent impulses affect independently functioning neuronal populations. It is suggested that a common principle of specific heterogenic signals arrival to distinct neuronal complexes exists for polysensory structures at different levels of the central nervous system.

Action Potentials↗
PubMed1985

The functional organization of the descending influences in the non-projection corticothalamic systems of the cat brain.

The local cooling of parietal, frontal or motor cortical areas; in cats under Nembutal anesthesia changed evoked potentials (EPs) in pulvinar, lateral posterior and medial dorsal thalamic nuclei. Parietal cortex, cooling led to rapid and significant changes of visual EP and delayed but strong changes of somatic EP in the pulvinar-lateral posterior complex. In contrast, frontal cortex cooling led to fast changes of somatic EP in medial dorsal nucleus and caused delayed weak changes: of visual EP. Motor cortex cooling resulted in rapid transformations of both potentials, though the changes of somatic EP were more pronounced in medial dorsal nucleus. The modifications of both EP primary-and secondary components were modal- and system-dependent. Results suggest that polysensory cortical areas exert modal-specific corticofugal influences on signals of different modality or on signals of the same modality but different subcortical genesis in the association nuclei.

Animals↗
PubMed1985

[Distribution of specific signals of different modality in the associative parietal area of the cat cortex].

In cats under nembutal anesthesia eliciting specific early components of association responses, the drug parietal distribution upon forepaw and thalamic stimulation was studied: relay somatic-ventrobasal complex (VB) and association nuclei, transmitting specific visual impulses in pulvinar (Pul) and lateral-posterior (LP) areas. Signals of maximum intensity were observed in response to peripheral and central stimulation near somatic area and in response to Pul and LP stimulation in the medial part of parietal cortex. Besides, a general principle revealing more intensive signals of different modality in the areas near lateral sulcus than in other parietal areas was established. The difference in processing of specific polysensory signals in various parietal areas and consequently, different involvement of the latter into the systemic action of the brain was proved, this being related to the character of topical organization of these signals.

Animals↗
PubMed1980

[Functional interaction between the parietal and motor regions of the cerebral cortex].

The role of interaction of parietal and motor nonprojectional areas in cortical integration was studied in acute experiments on cats. Their regulatory modal-nonspecific complex interaction including both the inhibitory and facilitating effects and characterized by the pulsatory aperiodic type of the progress was elucidated. A stronger influence of the parietal area on the motor as compared to that of the motor on the parietal area was recorded, with this influence being important for the motor integrative and trigger function. Interrelations of these areas differed from those between the parietal area and the projectional ones as well as from the latters relationships. These cortical formations demonstrate only mutual facilitating and tonic effect, their functional significance conditioning not only modal-specific or nonspecific influence type, but also a different role in mutual sensory supply.

Animals↗
PubMed1978

[Mechanisms of interaction between the parietal association and projection areas of the cat neocortex].

The pecularities of evoked potentials changes in the first visual, first somatic and parietal cortical areas locally cooled under nembutal anesthesia, as well as in the association thalamic nuclei (pulvinar and posterolateral) were studied in cats. Two types of interaction between these cortical structures were distinguished. Type I interaction was observed between all the studied cortical areas; type II--took place only between the parietal and each of the projection areas. Type I is suggested to be formed by cortical connections, type II--by direct and indirect subcortical ones. The peculiarities of involving the association parietal area into type I and II interactions according to its activation by different modality signals are discussed.

Animals↗
PubMedDate not supplied

[An analysis of the interaction of the parietal and visual regions of the cortex with the posterior lateral nucleus of the thalamus].

Cooling and ablation of the parietal associative (P) and primary visual projection (VI) areas in nembutalized cats revealed facilitating and inhibitory descending influences of the above areas on the postero-lateral nucleus (LP) of the ipsilateral thalamus where visual signals generate an early specific and a late unspecific components of heterogenous evoked responses. Unidirectional influences activating the early component and fully controlling the appearance and course of the late component are more manifest in P which is a part of the same associative brain system as LP; they are less manifest in VI which belongs to the projection system. At later cooling stages the centrifugal influences of P and VI are sometimes of opposite signs; this effect is connected with reciprocal relations between projection and association systems and processes or selfcontrol within the association system. The corticofugal effects also participate in the common activity of P and VI taking place to a certain degree at the level of the LP which activates these cortical structures.

Animals↗
PubMedDate not supplied

[The effect of neurotropic agents on evoked potentials of the association and projection regions of the cat neocortex].

Intensive non-specific inactivation of the cortex by means of its local cooling, in the cat anasthetized with nembutal, blocks in a similar way the early component of associative responses (ECAR) in the parietal area and the primary responses (PR) in the projection areas. In the case of local application of neurotropic drugs possessing specific and differentiated action on postsynaptic activity, the same ECAR changes require a somewhat higher concentration of the reagents as compared with the concentration that produces a similar PR transformation. The higher threshold of chemical sensitivity in ECAR than in the PR depends on the characteristics of the morpho-functional organization of the cortical formations. Dissimilar reactivity of the direct cortical response and of ECAR of the parietal area to the action of chemical drugs is related to the peculiarities of intracortical origin of these potentials which are due to the dissimilar nature of their generation in response to a direct and to a peripheral stimulation.

Animals↗