The Mechanisms of Repetitive Spike Generation in an Axonless Retinal Interneuron

Mark S. Cembrowski*, Stephen M. Logan, Miao Tian, Li Jia, Wei Li, William L. Kath, Hermann Riecke, Joshua H. Singer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)155-166
Number of pages12
JournalCell reports
Issue number2
StatePublished - Feb 23 2012

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology


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