Clustered plasticity in Long-Term Potentiation: How strong synapses persist to maintain long-term memory

Abstract

Abstract The storage of memory requires at least in part maintenance of long-term potentiation (LTP) in dendritic spine synapses. Neighboring synapses are frequently arranged into functional clusters. At present, it is still unclear how these clusters evolve, why they are stable for longer time periods and how spines interact within a cluster. In this review, we will provide an overview of current concepts of clustered plasticity and we will discuss cellular as well as molecular mechanisms that might be relevant for spine stability and associated functions in the context of LTP. We will propose that dynamics of initially formed clusters depend on compartmentalization of dendrites and that activity-dependent gene expression kicks in to preserve differences in synaptic weight. We will discuss how mechanisms of synaptic tagging, the presence of secretory organelles in dendrites and the incorporation of synaptic scaling factors that are encoded by immediate early genes interact to preserve clustered plasticity.