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S V Girman

Publications and source records attributed to S V Girman.

10 recordsLinked to original sources
PubMed1990

Electrophysiological properties of embryonic neocortex transplants replacing the primary visual cortex of adult rats.

Solid pieces of the occipital neocortex derived from 17-day rat fetuses were placed in a cavity formed by complete unilateral aspiration of the primary visual cortex in adult rats. Vital labeling of the brain with bisbenzimide was used to differentiate grafts from the host brain tissue. 2 to 10 months after operation electrophysiological experiments were performed in which neuronal activity and field potentials in transplants were recorded in response to sensory and electrical stimulation of the host brain. This study shows that in a large portion of the transplants (14 out of 25): (1) the majority of neurons (183/270) are controlled by visual stimuli and many of them respond to electrical stimulation of the lateral geniculate body (53/62) and the homotopic sites of the contralateral neocortex (28/62); latencies of these responses are within the ranges typical of the normal visual cortex; (2) there is a topical representation of the visual field on the transplants; (3) receptive field sizes, the preference to stationary flashes or to moving visual stimuli and the temporal response pattern of the grafted neurons are similar to those of the primary visual cortex. However, the field potentials evoked visually were recorded only in part of the transplants (8/14) which revealed clear neuronal visual responses, and field potential depth profile differed from that in visual cortex in situ. The functional organization of the transplants remained unchanged throughout the long-time testing. Taken together, these results suggest that after primary visual cortex removal, fetal neocortex transplants may be able to replace functionally the damaged neural circuitries of the host brain.

Animals↗
PubMed1989

Normalization of protein synthesis in brain cortex of rats after hypoxia by transplantation of embryonic nervous tissue.

It has been shown autoradiographically using 3H-lysine-3H-glycin mixture that acute hypoxic hypoxia leading to mass diffuse dystrophy of brain cortex neurons in rats causes a statistically significant decrease in the level of protein synthesis in cortical neurons. The biochemical study of the same material using 3H-leucine has demonstrated that the overall level of protein synthesis in the total cortical tissue (in nerve and non-nerve cells) is not reduced after hypoxia probably due to a high resistance of glial and other non-nerve cells to oxygen deficiency. Transplantation of embryonic nervous tissue into the brain of rats exposed to hypoxia results not only in normalization of the structure of a part of dystrophic neurons but also in a statistically significant increase in the level of protein synthesis which is retained up to the end of the experiment (i. e. for 120 days following the operation) in the total cortical tissue and reaches the normal value in neurons as established autoradiographically.

Animals↗
PubMed1988

[Electrophysiologic research on the afferent connections of embryonic neocortex allografts inserted into the projection zones of the cortex in adult rats].

Grafts of the rat fetal neocortex (the 17th-18th day of gestation) were placed into the cavity made by aspiration in the primary visual or somatosensory cortex of adult rats. Electrophysiological studies performed 3-3.5 months later showed that approximately in 50% of animals the neurons of the transplants responded to sensory stimuli of modality specific for cortical regions replaced by the transplant. These responses were elicited from local receptive fields that in some animals revealed topographic organization. Neuronal responses of transplants were elicited by local electrical stimulation of thalamic nucleus projecting to the cortical site of grafting, as by stimulation of contralateral homotopic cortical areas. Latency and temporal patterns of neuronal responses were similar to normal ones. Thus it may be concluded that afferent inputs to the cortical transplants retrace normal cortical inputs. The possible mechanisms of re-innervation of the grafts are discussed.

Afferent Pathways↗
PubMed1988

Changes of DNA synthesis in brain cortical cells after transplantation of embryonic nervous tissue into the brain of rats after hypoxia.

Autoradiographic and biochemical studies with 3H-thymidine have shown that after transplantation of embryonic nervous tissue of rats into the brain of adult rats, intact and subjected to acute hypoxic hypoxia causing mass dystrophy of neurons in the brain cortex of recipients, there occurs stimulation of DNA synthesis in non-nerve cells: glial cells, macrophages and endothelial cells. Stimulation is much more pronounced in the operated hemisphere than in the non-operated one and in intact rats than in hypoxia-subjected ones. On the whole, DNA synthesis was not observed in brain nerve cells except individual neurons located near the wound canal and the transplant.

Animals↗
PubMed1977

[Effect of binocular interaction of rat visual cortex neurons].

In anesthetized rats, out of 135 neurons recorded in binocular area within the striate cortex, 92 (74%) were binocular. 53 of these had well defined, mainly identical receptive fields on the two retinae. The range of relative horizontal and vertical disparity was found to be 5 degrees and 4 degrees respectively. These findings suggest that the visual system of the rat is capable to discover the spatial relationship using mechanisms of binocular fusion, in contrast to data obtained in rabbits.

Animals↗
PubMedDate not supplied

[The long-term effect of acute hypoxic hypoxia on shuttlebox avoidance learning in rats].

Long-term influence was studied of the acute hypoxic hypoxia seance on rats behaviour in situation of elaboration of the conditioned reaction of active avoidance of electric shocks in shuttle chamber. It was found that in 2.5-3 months after the hypoxia seance, the experimental animals significantly differed from the intact controls by dynamics of CR elaboration (rats which had hypoxia were ahead of the control ones) and by distribution of the conditioned reactions latencies (for experimental animals this distribution was shifted to minor values). The character of these behavioural shifts coincided with that observed in the group of rats with local unilateral hippocampus lesion. The obtained results and numerous data presented in literature on the influence of the hippocampus lesion on animals shuttle avoidance learning, allow to conclude that the seance of hypoxic hypoxia leads to the disturbance of the hippocampus function. This conclusion conforms to the data on diffusive death of the hippocampal and neocortical neurones as a result of hypoxia action.

Acute Disease↗