title: The mechanisms of repetitive spike generation in an axonless retinal interneuron.
abstract: Several types of retinal interneurons exhibit spikes but lack axons. One such neuron is the AII amacrine cell, in which spikes recorded at the soma exhibit small amplitudes (<10 mV) and broad time courses (>5 ms). Here, we used electrophysiological recordings and computational analysis to examine the mechanisms underlying this atypical spiking. We found that somatic spikes likely represent large, brief action potential-like events initiated in a single, electrotonically distal dendritic compartment. In this same compartment, spiking undergoes slow modulation, likely by an M-type K conductance. The structural correlate of this compartment is a thin neurite that extends from the primary dendritic tree: local application of TTX to this neurite, or excision of it, eliminates spiking. Thus, the physiology of the axonless AII is much more complex than would be anticipated from morphological descriptions and somatic recordings; in particular, the AII possesses a single dendritic structure that controls its firing pattern.
authors: Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL 60208, USA. cembrowski@u.northwestern.edu
authors: Mark S
authors: MS
authors: Cembrowski
authors: Stephen M
authors: SM
authors: Logan
authors: Miao
authors: M
authors: Tian
authors: Li
authors: L
authors: Jia
authors: Wei
authors: W
authors: Li
authors: William L
authors: WL
authors: Kath
authors: Hermann
authors: H
authors: Riecke
authors: Joshua H
authors: JH
authors: Singer
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D025042:Amacrine Cells / Q000166:cytology / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology*; D005260:Female; D007395:Interneurons / Q000166:cytology / Q000502:physiology*; D015640:Ion Channel Gating / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008959:Models, Neurological; D015221:Potassium Channels / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000502:physiology*; D013997:Time Factors
chemical_list: D015221:Potassium Channels