Synaptic plasticity and learning and memory: 15 years of progress.

Much has been learned over the past 15 years about the mechanisms of synaptic plasticity and their relationships to learning and memory processes. Some of the questions raised 15 years ago have been answered while others still remain elusive. This brief review attempts to evaluate the progress accomplished in this field and discusses four specific issues: (i) the relationships between mechanisms of synaptic plasticity and memory types, (ii) the relationships between stabilization of synaptic modifications and memory consolidation, (iii) the links between gene regulation and regulation of synaptic efficacy, and (iv) the relationships between synaptic dynamics and synaptic plasticity. Although it is relatively easy to identify areas in which progress has been made, it is also clear that many areas remain highly controversial and will keep neuroscientists busy for years to come.