Talking to the neighbours: The molecular and physiological mechanisms of clustered synaptic plasticity

- The dendritic branch is the integrative unit for synaptic plasticity.
- Clustered spines exhibit different dynamics in time and space.
- Molecular mechanisms of synaptic clustering differ in young and adult brain.
- Neighbouring spines share and compete for resources at dendritic segments.
- Intrinsic and extrinsic inhibitory signals shape synaptic clusters.

Synaptic connectivity forms the basis for neuronal communication and the storage of information. Experiences and learning of new abilities can drive remodelling of this connectivity and promotes the formation of spine clusters; dendritic segments with a higher spine density. Spines located within these segments are frequently co-activated, undergo different dynamics than synapses located outside of this dendritic compartment and have, in general, a longer lifetime.Several lines of evidence have shown that chemical synapses located close to each other share or compete for intracellular signalling molecules and structural resources. This sharing and competition directly influences spine dynamics. Spines can grow, shrink, increase or decrease the surface expression of receptors, channels and adhesion molecules or remain stable and unchanged over extended periods of time. Here we summarize recent discoveries and provide a closer look at spine clustering, dendritic segment-specific signalling and potential molecular mechanisms underlying associative and heterosynaptic plasticity.