title: Ultra-rapid axon-axon ephaptic inhibition of cerebellar Purkinje cells by the pinceau.
abstract: Excitatory synaptic activity in the brain is shaped and balanced by inhibition. Because inhibition cannot propagate, it is often recruited with a synaptic delay by incoming excitation. Cerebellar Purkinje cells are driven by long-range excitatory parallel fiber inputs, which also recruit local inhibitory basket cells. The axon initial segment of each Purkinje cell is ensheathed by basket cell axons in a structure called the pinceau, which is largely devoid of chemical synapses. In mice, we found at the single-cell level that the pinceau mediates ephaptic inhibition of Purkinje cell firing at the site of spike initiation. The reduction of firing rate was synchronous with the presynaptic action potential, eliminating a synaptic delay and allowing granule cells to inhibit Purkinje cells without a preceding phase of excitation. Axon-axon ephaptic intercellular signaling can therefore mediate near-instantaneous feedforward and lateral inhibition.
authors.affiliation: 1] Ecole Normale Supérieure, IBENS, Paris, France. [2] CNRS, UMR 8197, Paris, France. [3] INSERM, U1024, Paris, France.
authors.forename: Antonin
authors.initials: A
authors.lastname: Blot
authors.affiliation: 1] Ecole Normale Supérieure, IBENS, Paris, France. [2] CNRS, UMR 8197, Paris, France. [3] INSERM, U1024, Paris, France.
authors.forename: Boris
authors.initials: B
authors.lastname: Barbour
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D001703:Biophysics; D002531:Cerebellum / Q000166:cytology*; D004546:Elapid Venoms / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008959:Models, Neurological; D009412:Nerve Fibers / Q000502:physiology*; D009415:Nerve Net / Q000502:physiology*; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D011689:Purkinje Cells / Q000187:drug effects / Q000502:physiology*; D011724:Pyridazines / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
chemical_list: D004546:Elapid Venoms; D018756:GABA Antagonists; D009498:Neurotoxins; D011724:Pyridazines; C020273:dendrotoxin; C049853:gabazine