Emerging targets for the pharmacology of learning and memory.

Learning and memory are dynamic processes associated with modifications in morphology, biochemistry and physiology of the nervous system, that can be analysed at different levels of biological organization. Within this context, changes correlated with cognitive processes are identifiable at distinct cellular and molecular loci of the nervous system. Synaptic plasticity represents an experience-dependent alteration of neuronal properties that subserve learning and memory, and for which a neuronal network can be considered as a candidate for being part of an engram. Multiple molecular systems at various levels of the signal transduction cascade, such as those involving receptors, second messengers and gene expression, may be linked to synaptic remodelling during cognitive processes. After a brief overview of the various facets of memory and the higher levels of cerebral organization (with special attention to the hippocampus), this review is devoted to the presentation of some novel potential therapeutic targets within the signal transduction cascade that might be considered for rational pharmacological intervention to improve learning and memory in both diseased and healthy individuals. Copyright 2004 Elsevier Ltd.