SUMMARY

For almost a century we have been attempting to test the notion that information is stored in the brain as changes in the efficacy of synaptic connections on those neurons that are activated during learning. Since the discovery of long-term potentiation (LTP) in 1973, we have learned a great deal about the mechanisms underlying activity-dependent synaptic modification. To date, LTP is currently accepted as the most viable model of the type of modifications that would occur to process information and store the memory trace. Although over the past 25 years or so there has been a great deal of empirical data that allude to the possibility that this form of synaptic plasticity may well be one of the crucial mechanisms underlying learning and memory, we are still lacking definitive answers. We now know that LTP is the output of a series of biochemical and molecular events that in all likelihood results in a form of modification of neural networks. In this review we describe how the advances in molecular biology give us the tools to both investigate the mechanisms of synaptic plasticity and to apply these to investigations of the underlying mechanisms in learning and the formation of memories that have until now eluded us.

Introduction

One of the major concepts in our understanding of how memories are laid down in the brain lies in the notion that they (the memories) are encoded as spatiotemporal patterns of activity in cell networks, and not at the single cell level. An underlying principle is that the encoding and the storage of memory would therefore require some form of dynamic modification that is driven by the interaction between cells within these networks.