No abstract

An analysis of the influence of the posterolateral hypothalamus, which elicits positive reactions in behavioral testing, and of the midbrain raphe nuclei, on the plastic properties of the neurons of the visual cortex, was carried out in acute experimental conditions on diplacin-immobilized rabbits, based on a model of cortical trace processes. The different types of change in the reactivity of cortical cells under the influence of rhythmic sensory stimulation are described. The results of statistical analysis point to a dependence of hypothalamic and serotoninergic influences on the initial reaction of neurons to sensory stimulation. It is demonstrated that the plastic changes in the activity of cortical neurons reveal similar features under the influence both of the "positive" emotiogenic zone of the hypothalamus and of the midbrain raphe nuclei. Similar regularities are observed also in an analysis of the interaction of cortical neurons which were recorded in one microvolume identified by the method of cross-interval histograms.

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The features of the exploratory behavior in the open field, of the learning of a conditioned-reflex food-procuring reaction, and of the shift in the level of biogenic amines of the brain was studied in Wistar rats with local injections of the specific neurotoxins 6-hydroxydopamine (6-OH-DA) and 5,7-dihydroxytryptamine (5,7-DHT). It was shown that damage to the structure of the serotoninergic or catecholaminergic systems of the frontal cortex and hippocampus caused by local injection of 6-OH-DA and 5,7-DHT into the neocortex is accompanied by multidirectional changes in the exploratory behavior and learning of the animals.