Conditioned reflex and electrical activities of the hippocampus during the random use of heterogeneous triggering stimuli

In dogs with electrodes chronically implanted in the hippocampus, the conditioned activity, heart rate frequency and spectral characteristics of the hippocampal theta-rhythm were studied in conditions of irregular presentation after a preparatory stimulus now of alimentary and now of defensive triggering conditioned stimuli. It is shown that uncertainty of alimentary or defensive reinforcement is a stronger emotiogenic factor than the action of the triggering defensive conditioned stimulus. Changes in electrical hippocampal activity and autonomous activity depend, along with other factors, on forecasted volume of the forthcoming motor activity. The speed of instrumental conditioned reflexes formation correlates with the hippocampal theta-rhythm frequency, typical for the given animal.