Abstract: The effects of learning-dependent long-term potentiation (LTP) in di-fferent development phases on the learning was investigated in freely mo-ving rats. The results showed: the acquisition of new conditional responsewas facilitated by the learning-dependent LTP in both the formation pha-se and consolidation phase, appeared with the former conditioning in thehippocampal CA3 region, but the facilitated effect of learning-dependentLTP in the consolidation phase is a little larger than in the formation ph-ase. As the learning-dependent LTP was extincted, no facilitated effecton the new learning appeared. However, the enhanced population spike(PS) did not increase further during the establishment of the new condi-tioning. Therefore, it is suggested that there might be some different chan-ges in synaptic plasticity at the different development phase of learning-dependent LTP and a "saturated" phenomenon in the synaptic potentia-tion produced by behavioural training. These results support further thatlearning-dependent LTP might be one of the neuronal mechanisms under-lying behavioral learning and memory.

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