Synaptically Induced Long-Term Modulation of Electrical Coupling in the Inferior Olive

Summary

Electrical coupling mediated by gap junctions is widespread in the mammalian CNS, and the interplay between chemical and electrical synapses on the millisecond timescale is crucial for determining patterns of synchrony in many neural circuits. Here we show that activation of glutamatergic synapses drives long-term depression of electrical coupling between neurons of the inferior olive. We demonstrate that this plasticity is not triggered by postsynaptic spiking alone and that it requires calcium entry following synaptic NMDA receptor activation. These results reveal that glutamatergic synapses can instruct plasticity at electrical synapses, providing a means for excitatory inputs to homeostatically regulate the long-term dynamics of microzones in olivocerebellar circuits.

Highlights

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  Chemical synapses trigger long-term depression of inferior olive electrical coupling

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  Depression of electrical coupling requires NMDAR activation and calcium entry

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  Plasticity is not triggered by postsynaptic spiking alone and EPSPs remain unchanged

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  Excitatory inputs can thus homeostatically regulate synchrony patterns in the olive

Abstract

The interplay between electrical and chemical synapses is crucial for determining patterns of synchrony in neuronal networks. Recording in the inferior olive, Mathy et al. show that coincident excitatory synaptic input and spiking can cause a sustained suppression of electrical coupling.