Temporal Pattern Dependent Spatial-Distribution of LTP in the Hippocampal CA1 Area Studied by an Optical Imaging Method
Long-term potentiation (L TP) in the CA 1 area of hippocampus are highly sensitive to the higher order statistical characteristics of the stimulus (correlation between successive pairs of inter-stimulus intervals) (Tsukada 1991, 1992, 1993, Aihara 1991). The temporal-pattern sensitivity in LTP was identified in a slice preparation by using the optical imaging method. In this experiment. we found that spatial pattern of LTP in CA 1 area differed depending on the temporal pattern of stimulus; positively correlated sequences were much more effective (large area) in producing LTP. while negatively correlated sequences were ineffective (small area). In addition. the spatial pattern of LTP was closely related to the position where the repetitive firing of population spikes. Involving dynamic formation of LTP through the activities of NMDA channels, Was evoked during the period of temporal-pattern stimuli. These results suggest that there is a transformation from the temporal pattern into the spatial pattern in coding process of the hippocampal learning system. and that hippocampus uses a temporal code as an index.
KeywordsTungsten NeuroL NMDA Kato Tetanus
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