MORPHOLOGICAL-CHANGES ASSOCIATED WITH LONG-TERM POTENTIATION

Long-term potentiation (LTP) is a longlasting form of synaptic plastic ity induced by brief repetitive afferent stimulation that is thought t o be associated with learning and memory. It is most commonly studied in the hippocampus where it may last for several weeks, and involves t he synthesis of new proteins that might play a structural role. In thi s review we summarize the evidence in favor of modifications of neuron al architecture during LTP. We focus our attention on changes occurrin g at the level of single synapses, including components of postsynapti c dendrites (dendritic spines, the postsynaptic density, and synaptic curvature), of presynaptic terminals, and the formation of new synapse s. We conclude that although many morphological changes at various sit es have been observed during LTP, there is no definitive proof in favo r of structural changes associated with LTP. However, morphological mo difications remain a valid candidate for mechanisms of learning and me mory.