Biomedical subjects
Publications and source records attributed to L S Gambarian.
Formation of optical EPs was studied in alert rabbits during postnatal ontogenesis. The pathways of the transmission of light stimuli to the brain cortex were found to develop heterogeneously causing the EPs to have different forms in the early stages of ontogenesis.
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The role of the pallidum in memory mechanisms was studied in cats by different methods of conditioned reflexes. It has been shown that a bilateral partial lesion of the Globus pallidus leads to "forgetting" sequences in delayed alternation and electrical punishment in previous experiments as well as to disturbances of the perceptual memory.
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2nd somatosensory area (C2) was shown to have modulating influence on evoked activity of the 1st somatosensory and visual areas. Electrical stimulation of C2 evoked short latency potentials in the structures of paleocortex (hippocampus) and striatum (putamen, caudate nucleus). Analysis of the data obtained here and elsewhere (19) suggests the important role of C2 in mechanisms of selection, comparison and integration of adequate sensory information under conditions of uncertainty, for the programming of behaviour.
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Bilateral ablation of the putamen results in temporary disappearance of natural as well as artificial conditioned motor reflexes in cats. Further training is necessary for their reestablishment. Restored conditioned reflexes appear with a long latency. After partial bilateral ablation of the putamen, animals that have been trained not only to press a pedal, but also to make a choice between a right or left feeding tray, lose the latter ability. After the reestablishment of conditioned reflexes, the animal makes a correct choice of side only in 68--70% of cases. After total bilateral ablation of the putamen the animals lose artificial conditioned reflexes. The results suggest that the putamen has a close relation to the mechanisms of learning and memory.
Bilateral ablation of the pallidum halves the duration of extinction of conditioned motor food reflexes and contributes to 30 to 50% extinction of the electro-defensive reflexes. Pallidum functional depression by potassium chloride or novacaine leads to a temporary total depression of conditioned motor food reflexes. Depending on the frequency of pallidum stimulation, synchronization or desynchronization of the cortical bioelectrical activity is observed. Ablation of the pallidum in anaesthetized cats results in a high amplitude and low-frequency cortical activity. Injection of large doses of potassium chloride into the pallidum results in a forced running forward which lasts 30 to 40 min. The pallidum is considreed as a structure controlling the cortex activity, which takes part in the mechanisms of sensory information processes in the course of adaptive behaviour.
At studying the use by the rats of previous experience in conditions of change of the dominant need and change of learning situation, data were obtained that allowed to evaluate differently the significance of drinking and defensive motivations as a factor providing for dissociated learning of animals. Significance is discussed of motivation factor during the use by the rats of one or other behavioural strategies in the process of learning.