CELLULAR AND MOLECULAR-BASES OF MEMORY - SYNAPTIC AND NEURONAL PLASTICITY

Discoveries made during the past decade have greatly improved our unde rstanding of how the nervous system functions. This review article exa mines the relation between memory and the cellular mechanisms of neuro nal and synaptic plasticity in the central nervous system, Evidence in dicating that activity-dependent short-and long-term chang es in stren gth of synaptic transmission are important for memory processes is exa mined. Focus is placed on one model of synaptic plasticity called long -term potentiation, and its similarities with memory processes are ill ustrated. Recent studies show that Me regulation of synaptic strength is bidirectional (e.g., synaptic potentiation or depression). Mechanis ms involving intracellular signaling pathways that regulate synaptic s trength are described, and the specific roles of calcium, protein kina ses, protein phosphatases, and retrograde messengers are emphasized. E vidence suggests that changes in synaptic ultrastructure; dendritic ul trastructure, and neuronal gene expression may also contribute to mech anisms of synaptic plasticity. Also discussed are recent findings abou t postsynaptic mechanisms that regulate short-term synaptic facilitati on and neuronal burst-pattern activity, as well as evidence about the subcellular location (presynaptic or postsynaptic) of mechanisms invol ved in long-term synaptic plasticity.