Synapse specificity and long-term information storage.

Abstract

The dendrites of a typical neuron in the central nervous system bear at least 1000 postsynaptic specializations indicating that in principal the individual neuron can process and store many bits of information. Electrophysiological experiments have also revealed that anatomically isolated groups of synapses on the same cell can separately process plastic events. Finally, many studies of behavioral and synaptic plasticity have demonstrated that long-lasting changes in synaptic transmission and behavior require both gene transcription and mRNA translation. To understand long-term information storage, then, the problem is to determine how the potentiated (or depressed) synapses of a single neuron become selectively modified during the long-lasting phases of synaptic plasticity. That is, how do the products of transcription and/or translation reach the modified synaptic sites without affecting the unmodified sites within the same neuron? There are at least three ways this could occur, including the selective capture of broadly distributed newly synthesized proteins by potentiated sites, the selective transport of newly synthesized proteins to potentiated sites, and the site-specific local production of new proteins by dendritic protein synthesis machinery (Figure 1; reviewed bySossin 1996; Goelet et al. 1986).