title: Control of firing patterns through modulation of axon initial segment T-type calcium channels.
abstract: Spontaneously active neurons typically fire either in a regular pattern or in bursts. While much is known about the subcellular location and biophysical properties of conductances that underlie regular spontaneous activity, less is known about those that underlie bursts. Here, we show that T-type Ca(2+) channels localized to the site of action potential initiation in the axon initial segment play a pivotal role in spontaneous burst generation. In auditory brainstem interneurons, axon initial segment Ca(2+) influx is selectively downregulated by dopaminergic signalling. This regulation has marked effects on spontaneous activity, converting the predominant mode of spontaneous activity from bursts to regular spiking. Thus, the axon initial segment is a key site, and dopamine a key regulator, of spontaneous bursting activity.
authors: Oregon Hearing Research Centre and Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA. kbender@gallo.ucsf.edu
authors: Kevin J
authors: KJ
authors: Bender
authors: Victor N
authors: VN
authors: Uebele
authors: John J
authors: JJ
authors: Renger
authors: Laurence O
authors: LO
authors: Trussell
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020747:Calcium Channels, T-Type / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism; D015536:Down-Regulation; D016057:Evoked Potentials, Auditory, Brain Stem; D007395:Interneurons / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA
chemical_list: D020747:Calcium Channels, T-Type; D002118:Calcium; D004298:Dopamine