Ephaptic Coupling Promotes Synchronous Firing of Cerebellar Purkinje Cells

Kyung-Seok Han, Chong Guo, Christopher H Chen, Laurens Witter, Tomas Osorno, Wade G Regehr

Research output: Contribution to JournalArticleAcademicpeer-review


Correlated neuronal activity at various timescales plays an important role in information transfer and processing. We find that in awake-behaving mice, an unexpectedly large fraction of neighboring Purkinje cells (PCs) exhibit sub-millisecond synchrony. Correlated firing usually arises from chemical or electrical synapses, but, surprisingly, neither is required to generate PC synchrony. We therefore assessed ephaptic coupling, a mechanism in which neurons communicate via extracellular electrical signals. In the neocortex, ephaptic signals from many neurons summate to entrain spiking on slow timescales, but extracellular signals from individual cells are thought to be too small to synchronize firing. Here we find that a single PC generates sufficiently large extracellular potentials to open sodium channels in nearby PC axons. Rapid synchronization is made possible because ephaptic signals generated by PCs peak during the rising phase of action potentials. These findings show that ephaptic coupling contributes to the prevalent synchronization of nearby PCs.

Original languageEnglish
Pages (from-to)564-578.e3
Number of pages19
Issue number3
Early online date2 Oct 2018
Publication statusPublished - 7 Nov 2018


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