[Changes in the pattern of hippocampal neuron discharge as a reflection of the reinforcement effect in self-stimulation].

Changes of the unit activity patterns occurred in the rabbit dorsal hippocampus after self-stimulation. The changes occurred mostly in the theta-burst neurons and in neurons with reduction of spike amplitudes within each burst of discharges. Spontaneous activity of these neurons revealed bimodal histograms of interspike interval distribution. Within 1--3 sec after the self-stimulation the burst-type activity transformed into the regular or arrhythmic one with monomodal form of histogram. Spontaneously regular and arrhythmic neurons revealed no change of patterns. The findings corroborate the Grshtian hypothesis that the reward effect in self-stimulation is correlated with the motor rebound-effect. Experiments with cessation of reinforcing stimulus suggested a dependence of the burst-type pattern of discharges of the hippocampal neurons on the functional state of expectancy of the reinforcing stimulus.