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  • Title: Spatial exploration induces a persistent reversal of long-term potentiation in rat hippocampus.
    Author: Xu L, Anwyl R, Rowan MJ.
    Journal: Nature; 1998 Aug 27; 394(6696):891-4. PubMed ID: 9732871.
    Abstract:
    Experience-dependent long-lasting increases in excitatory synaptic transmission in the hippocampus are believed to underlie certain types of memory. Whereas stimulation of hippocampal pathways in freely moving rats can readily elicit a long-term potentiation (LTP) of transmission that may last for weeks, previous studies have failed to detect persistent increases in synaptic efficacy after hippocampus-mediated learning. As changes in synaptic efficacy are contingent on the history of plasticity at the synapses, we have examined the effect of experience-dependent hippocampal activation on transmission after the induction of LTP. We show that exploration of a new, non-stressful environment rapidly induces a complete and persistent reversal of the expression of high-frequency stimulation-induced early-phase LTP in the CA1 area of the hippocampus, without affecting baseline transmission in a control pathway. LTP expression is not affected by exploration of familiar environments. We found that spatial exploration affected LTP within a defined time window because neither the induction of LTP nor the maintenance of long-established LTP was blocked. The discovery of a novelty-induced reversal of LTP expression provides strong evidence that extensive long-lasting decreases in synaptic efficacy may act in tandem with enhancements at selected synapses to allow the detection and storage of new information by the hippocampus.
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