[Effect of serotonin on self stimulation and conditioned avoidance reactions in rats].

It has been shown that serotonin influences self-stimulation and avoidance conditioned reactions in rats in a different way. Serotonin administration caused a reorganization of self-stimulation process and enhanced its frequency; the avoidance reaction grew weaker and was achieved with a longer latency. Alternation of stages of activation and inhibition was observed in the EEG of the neocortex, hypothalamus and hippocampus as well as shifts in the heart rate. These changes did not always correlate with the animals' behaviour. Unidirectional, yet different serotonin effects on various behavioral reactions, brain electrical activity and vegetative processes testify to a relative independence of their mechanisms.