title: Differences between synaptic plasticity thresholds result in new timing rules for maximizing long-term potentiation.
abstract: The fundamental observation that the temporal spacing of learning episodes plays a critical role in the efficiency of memory encoding has had little effect on either research on long-term potentiation (LTP) or efforts to develop cognitive enhancers. Here we review recent findings describing a spaced trials phenomenon for LTP that appears to be related to recent evidence that plasticity thresholds differ between synapses in the adult hippocampus. Results of tests with one memory enhancing drug suggest that the compound potently facilitates LTP via effects on 'high threshold' synapses and thus alters the temporally extended timing rules. Possible implications of these results for our understanding of LTP substrates, neurobiological contributors to the distributed practice effect, and the consequences of memory enhancement are discussed. This article is part of a Special Issue entitled 'Cognitive Enhancers'.
authors: Department of Psychiatry and Human Behavior, University of California, Irvine, CA 92697-4260, USA.
authors: Gary
authors: G
authors: Lynch
authors: Enikö A
authors: EA
authors: Kramár
authors: Alex H
authors: AH
authors: Babayan
authors: Gavin
authors: G
authors: Rumbaugh
authors: Christine M
authors: CM
authors: Gall
mesh_terms: D000818:Animals; D003071:Cognition / Q000187:drug effects; D003072:Cognition Disorders / Q000188:drug therapy / Q000517:prevention & control; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017774:Long-Term Potentiation / Q000187:drug effects; D008568:Memory / Q000187:drug effects; D009473:Neuronal Plasticity / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018697:Nootropic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D058573:Performance-Enhancing Substances / Q000494:pharmacology / Q000627:therapeutic use; D013569:Synapses / Q000187:drug effects* / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects*
chemical_list: D018697:Nootropic Agents; D058573:Performance-Enhancing Substances