Long-Term Potentiation and Learning

Abstract

Long-term potentiation (LTP), a relatively long-lived increase in synaptic strength, remains the mot popular model for the cellular process that may underlie information storage within neural systems. The strongest arguments for a role of LTP in memory are theoretical and involve Hebb's Postulate, Marr's theory of hippocampal function, and neural network theory. Considering LTP research as a whole, few studies have addressed the essential question: Is LTP a process involved in learning and memory? The present manuscript reviews research that attempts to link LTP with learning and memory, focusing on studies utilizing electrophysiological, pharmacological, and molecular biological methodologies. Most evidence firmly supports a role for LTP in learning memory. However, an unequivocal experimental demonstration of a contribution of LTP to memory is hampered by our lack of knowledge of the biological basis of memory and of the ways in which memories are represented in ensembles of neurons, the existence of a variety of cellular forms of LTP, and the likely resistance of distributed memory stores to degradation by treatments that incompletely disrupt LTP.

Aspects of the Search for Neural Mechanisms of Memory

“…(1975, p. 232) pointed out, the brain sites involved in learning and memory storage should be identified by converging evidence from neurochemical changes, localized in-hibition of neurochemistry, and electrophysiological recording; lesion studies should be added to this list. Martinez & Derrick (1996) in this volume discuss whether long-term potentiation (LTP)-which involves neurochemical, electrophysiological, and neuroanatomical changes-is a memory mechanism. While conceding that convincing proof does not exist that LTP is involved in memory, they believe that after 20 years of research on it, "LTP remains the best single candidate for a cellular process of synaptic change that may underlie learning and memory in the vertebrate brain" (p. 198).…”

“…Whether learning-induced anatomical changes in the nervous system are necessary for storage of long-term memory has been discussed by several authors, including Morris (1989), Greenough et al (1990), and Martinez & Derrick (1996). Greenough et al (1990, pp.…”

Multiple behavioral anomalies in GluR2 mutant mice exhibiting enhanced LTP

“…Synaptic strengthening such as LTP has been the focus of attention in behavioral and molecular neuroscience studies [43,55]. LTP has been an attractive hypothesis to explain the cellular mechanisms underlying certain forms of learning and memory [5,43,46].…”

“…LTP has been an attractive hypothesis to explain the cellular mechanisms underlying certain forms of learning and memory [5,43,46]. Both pharmacological [45] and genetic [25,55] manipulations of LTP appear to be associated with hippocampal dependent behavioral alterations that may be measured as impaired relational (spatial) learning [43,4].…”

A post-tetanic time window for the reinforcement of long-term potentiation by appetitive and aversive stimuli

“…Long-term potentiation (LTP), an activity-dependent, longlasting increase in synaptic strength observed at monosynaptic junctions in the mammalian forebrain, has many features that make it a plausible cellular mechanism for many types of learning and memory (8)(9)(10)(11). The demonstration of both correlations and interactions between hippocampal LTP and hippocampus-dependent learning has provided further support for this idea (7,8,11).…”