Biomedical subjects

G P Demianenko

Publications and source records attributed to G P Demianenko.

3 recordsLinked to original sources

PubMed1995

Constancy and variability in cortical structure. A study on synapses and dendritic spines in hedgehog and monkey.

Synapses and dendritic spines were investigated in the parietal cortex of the hedgehog (Erinaceus europaeus) and the monkey (Macaca mulatta). There was no significant difference in the density of synapses between the two species (14 synapses/100 microns2 in the hedgehog, 15/100 microns2 in the monkey), neither in the size of the synaptic junctions, in the proportion of Type I and Type II synapses (8-10% were of Type II in the hedgehog, 10-14% in the monkey) nor in the proportion of perforated synapses (8% in the hedgehog, 5% in the monkey). The only striking difference at the electron microscopic level concerned the frequency of synapses in which the postsynaptic profile was deeply indented into the presynaptic terminal. Such synapses were 10 times more frequent in the monkey. Dendritic spines were investigated in Golgi-preparations. The density of spines along dendrites was similar in both species. The results are discussed with regard to connectivity in the cortex of small and large brains.

Animals↗

PubMed1983

Stellate cells differentiate successively in the cat sensorimotor cortex during early postnatal ontogeny.

Golgi and Golgi-Kopsch techniques were used to investigate maturation of stellate and pyramidal cells and development of stellate-pyramidal connections in kittens of the following ages: 2, 7, 14, 21, 28 and 34 days. By two weeks, stellate cells in layer V have become mature. Layer III stellate cells with vertical axon ramifications are differentiated by 2-3 weeks of life and in 3-week-olds the horizontal spread of axon collaterals amounts to 1300 micrometer. Layer II stellate cells which are poorly developed n newborns acquire the greatest number of collaterals and a complex axon branching pattern by 4 weeks of age.

Animals↗

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↗