Differences in the spike activity of hippocampus and neocortex neurons in active and passive rabbits in emotionally negative situations.

Autocorrelation histograms were used to compare the spike activity of neurons in the hippocampus (field CA1) and parietal-temporal areas of the neocortex in groups of active and passive rabbits during exposure to emotionally significant stimuli. The mean spike frequencies of single hippocampal neurons were greater in active rabbits than in passive rabbits, and also showed more frequent discharge grouping and periodicity, and frequencies in the theta-1 range (6.9-19.0 Hz) were more often seen in discharge periodicity (in baseline conditions and during active motor reactions to stimuli), while theta-2 frequencies (4.0-6.0 Hz), conversely, were less common (on freezing). Hippocampal neuron spike activity during exposure to stimuli showed more marked changes in active rabbits than in passive rabbits. Intergroup differences in neuron spike activity were smaller in the neocortex than in the hippocampus. These results lead to the conclusion that individual-typological differences in the behavior of animals in emotionally negative situations are reflected in neuron activity in hippocampal field CA1 and the parietal-temporal areas of the neocortex. It is suggested that active and passive rabbits have different levels of activation of the septohippocampal system and functional differences in the afferent inputs to hippocampal field CA1.