Heterosynaptic structural plasticity on local dendritic segments of hippocampal CA1 neurons

By Won Chan Oh, Laxmi Kumar Parajuli, K. Zito. 2014

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SUMMARY Competition between synapses contributes to activity-dependent refinement of the nervous system during development. Does local competition between neighboring synapses drive circuit remodeling during experience-dependent plasticity in the cerebral cortex? Here, we examined the role of activity-mediated competitive interactions in regulating dendritic spine structure and function on hippocampal CA1 neurons. We found that high-frequency glutamatergic stimulation at individual spines, which leads to input-specific synaptic potentiation, induces shrinkage and weakening of nearby unstimulated synapses. This heterosynaptic plasticity requires potentiation of multiple neighboring spines, suggesting that a local threshold of neural activity exists beyond which inactive synapses are punished. Notably, inhibition of calcineurin, IP3Rs, or group I mGluRs blocked heterosynaptic shrinkage without blocking structural potentiation, and inhibition of CaMKII blocked structural potentiation without blocking heterosynaptic shrinkage. Our results support a model in which activity-induced shrinkage signal, and not competition for limited structural resources, drives heterosynaptic structural and functional depression during neural circuit refinement.

Subfields: Cellular and Molecular Neuroscience, Cognitive Neuroscience