[Comparison of the effect of serotonin administered into the dorsal hippocampus on conditioned passive and active...

It has been established that intrahippocampal bilateral injection of 5-HT in a dose of 2 micrograms prolonged the time of passive avoidance reflex retention, inhibiting the retrieval of active avoidance reflex and facilitating its extinction. The data obtained show the dependence of 5-HT effect on reinforcing and triggering properties of spatial-environmental and phasic conditioned stimuli. It is suggested that intrahippocampal 5-HT administration was responsible for the retrieval of traces of conditioned reinforced stimuli.