title: Rapid State-Dependent Alteration in Kv3 Channel Availability Drives Flexible Synaptic Signaling Dependent on Somatic Subthreshold Depolarization.
abstract: In many neurons, subthreshold depolarization in the soma can transiently increase action-potential (AP)-evoked neurotransmission via analog-to-digital facilitation. The mechanisms underlying this form of short-term synaptic plasticity are unclear, in part, due to the relative inaccessibility of the axon to direct physiological interrogation. Using voltage imaging and patch-clamp recording from presynaptic boutons of cerebellar stellate interneurons, we observed that depolarizing somatic potentials readily spread into the axon, resulting in AP broadening, increased spike-evoked Ca2+entry, and enhanced neurotransmission strength. Kv3 channels, which drive AP repolarization, rapidly inactivated upon incorporation of Kv3.4 subunits. This leads to fast susceptibility to depolarization-induced spike broadening and analog facilitation independent of Ca2+-dependent protein kinase C signaling. The spread of depolarization into the axon was attenuated by hyperpolarization-activated currents (Ihcurrents) in the maturing cerebellum, precluding analog facilitation. These results suggest that analog-to-digital facilitation is tempered by development or experience in stellate cells.
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
authors.forename: Matthew J M
authors.initials: MJM
authors.lastname: Rowan
authors.affiliation: Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA. Electronic address: jason.christie@mpfi.org.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Christie
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000378:metabolism / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism / Q000502:physiology; D007395:Interneurons / Q000378:metabolism / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000502:physiology; D011493:Protein Kinase C / Q000378:metabolism; D051670:Shaw Potassium Channels / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013569:Synapses / Q000378:metabolism* / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: C115399:Kcnc4 protein, mouse; D015221:Potassium Channels; D051670:Shaw Potassium Channels; D011493:Protein Kinase C; D002118:Calcium
keywords: Bouton; HCN; Kv3.4; analog signaling; axon; short-term plasticity