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Biomedical subjects

A I Karamian

Publications and source records attributed to A I Karamian.

At least 19 recordsLinked to original sources
PubMed1990

[The role of beta-endorphin in regulating the conditioned reflex activity of cats].

The role of beta-endorphin in regulation of instrumental food conditioning and in more complicated forms of nervous activity in cats was found to involve a facilitating unspecific effect both on positive and negative food conditioning, the latter having a general adaptive character. The influence of the same small doses of beta-endorphin (10 mkg/kg - 15 x 10(-6) mkg/kg) on the choice responses was more complicated and depended on the basic level of conditioning and the typology of animals. Possible mechanism of the beta-endorphin effect on higher nervous activity, is discussed.

Animals↗
PubMed1984

[New electrophysiologic data on localizing visual representation in the limbic area of the neocortex].

In the limbic part of the rat neocortex, afferents from the retino-geniculo-cortical and retino-tecto-thalamo-cortical visual subsystems converge to the area 29. A specific feature of the area 29 responses to stimulation of thalamic visual nuclei (the LGB and the postero-lateral nucleus) involves gradualness of their appearance during rhythmic stimulation. The responses have an initial negative phase, are resistant against nembutal, have a short and stable latency, their neuronal reaction being phasic in nature and showing dependence on physical parameters of stimulation. These intermediate type reactions possess features of both specific and unspecific responses of the neocortex which seems to be characteristic of the area 29 function.

Afferent Pathways↗
PubMed1980

Structural and functional characteristics of hedgehog polysensory cortical zone.

The study of the neuronal organization of the hedgehog associative cortical zone revealed that besides primitive characteristics this area possesses a number of progressive features. An electrophysiological approach revealed a great number of polysensory neurons. The method, based on the HRP retrograde axonal transport, enabled us to discover the connections between primitive associative LP and MD thalamic nuclei and the associative cortex. Motor conditioned reflexes connected with visual discrimination as well as reflexes to signals of different modalities were elaborated quite easily. Conditioning to a simultaneous visual-auditory complex was found impossible in hedgehogs. Bilateral ablation of associative area results in disruption of the fine components of sensorimotor integration. It is likely that a primitively organized associative system in hedgehogs participates in the formation of sensorimotor synthesis, but fails to realize complex acts of intersensory integration.

Animals↗
PubMed1975

[Corticalization of 2 regions of the visual system in the evolution of vertebrates].

Data on the evolution of the visual system in the phylogenetic scale of vertebrates are reported. Visual projections in the telencephalon of cyclostomes (lampreys) and retinothalamo-telencephalic channel in elasmobranches (skates) are shown. In amphibians (frogs) and reptiles (turtles) the existence of two visual subsystems (retino-thalamo-telencephalic and retino-tecto-thalamo-telencephalic) is determined, both being overlapped partially at the level of n. geniculatus lateralis and totally in the telencephalon. In turtles earlier visual and tectal impulses towards the telencephalon proved to be relayed in n. geniculatus lateralis and later ones--in n. rotundus. In mammals (rats) visual tecto-cortical connections are shown to have one synaptic relay in thalamic structures since cortical potentials evoked by stimulation of the colliculus superior in rats posses a rather short latency. Significant latency shortening of tectal visual responses in monkeys, as compared with the latency of the respective potentials in turtles (chronic identical experiments), supports the idea of the progressive development of the tectal division of the visual system in the vertebrate phylogony. It is concluded that both divisions of the visual system--retino-thalamic and retino-tectal underwent corticalization at earlier evolutionary stages.

Animals↗