Abstract: This paper, by using the method of combining electrophysiology wi-th behavior, deals with the hippocampal synaptic efficacy to the acquisit-ion, consolidation and extinction of conditioned responses and its relati-on with the signals of different types of senses as conditioned stimulus(CS). The long-term potentiation (LTP) of the synaptic efficacy in hippo-campal dentate area was not only significantly obvious in the acquisitionor conditioned discrimination response, but persisted because of the consoli-dated training after the acquisition of the conditioned response. Further-more, the duration of persistence was directly proportional to the trialsin the consolidated training. After this learning-dependent LTP disappea-red, the conditioned response disappeared as well. But in the conditionedgustatory detestation there was no LTP phenomenon. Therefore, these results, at the level of synaptic efficacy, further substantiate the viewpointof our research laboratory that hippocampus plays a different role in the-memory of conditioned responses with the signals of different typesof senses as CS, and that hippocampus participates not only in learning,but also in the retention of memory. These results suggest that this ?are-ning-dependent LTP is closely related to learning and memory.

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