Spine changes associated with long-term potentiation

High-frequency stimulation of excitatory synapses in many regions if the br ain triggers a lasting increase in the efficacy of synaptic transmission re ferred to as long-term potentiation (LTP) and believed to contribute to lea rning and memory. One hypothesis proposed to account for the stability and properties of this functional plasticity is a structural remodeling of spin e synapses. This possibility has recently received support from: Several st udies. It has been found that spines are highly dynamic structures, that th ey can be formed very rapidly, and that synaptic activity and calcium modul ate changes in spine shape and formation of new spines. Ultrastructural ana lyses bring additional support to these observations and suggest that LTP i s associated with a remodeling of the postsynaptic density (PSD) and a proc ess of spine duplication. This new information is reviewed and interpreted in light of other recent advances concerning the mechanisms of LTP and espe cially the role of postsynaptic glutamate receptor turnover in this form of plasticity. Taken together, a view is emerging that suggests that morpholo gic changes of spine synapses are associated with LTP and that they not onl y correlate with, but probably:also contribute to the increase in synaptic transmission. Hippocampus 2000;10:596-604, (C) 2000 Wiley-Liss, Inc.