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Developmentally Regulated Rebound Depolarization Enhances Spike Timing Precision in Auditory Midbrain Neurons.

Authors
  • Sun, Hongyu1
  • Zhang, Hui1
  • Ross, Alysia1
  • Wang, Ting Ting1
  • Al-Chami, Aycheh1
  • Wu, Shu Hui1
  • 1 Department of Neuroscience, Carleton University, Ottawa, ON, Canada. , (Canada)
Type
Published Article
Journal
Frontiers in Cellular Neuroscience
Publisher
Frontiers Media SA
Publication Date
Jan 01, 2020
Volume
14
Pages
236–236
Identifiers
DOI: 10.3389/fncel.2020.00236
PMID: 32848625
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

The inferior colliculus (IC) is an auditory midbrain structure involved in processing biologically important temporal features of sounds. The responses of IC neurons to these temporal features reflect an interaction of synaptic inputs and neuronal biophysical properties. One striking biophysical property of IC neurons is the rebound depolarization produced following membrane hyperpolarization. To understand how the rebound depolarization is involved in spike timing, we made whole-cell patch clamp recordings from IC neurons in brain slices of P9-21 rats. We found that the percentage of rebound neurons was developmentally regulated. The precision of the timing of the first spike on the rebound increased when the neuron was repetitively injected with a depolarizing current following membrane hyperpolarization. The average jitter of the first spikes was only 0.5 ms. The selective T-type Ca2+ channel antagonist, mibefradil, significantly increased the jitter of the first spike of neurons in response to repetitive depolarization following membrane hyperpolarization. Furthermore, the rebound was potentiated by one to two preceding rebounds within a few hundred milliseconds. The first spike generated on the potentiated rebound was more precise than that on the non-potentiated rebound. With the addition of a calcium chelator, BAPTA, into the cell, the rebound potentiation no longer occurred, and the precision of the first spike on the rebound was not improved. These results suggest that the postinhibitory rebound mediated by T-type Ca2+ channel promotes spike timing precision in IC neurons. The rebound potentiation and precise spikes may be induced by increases in intracellular calcium levels. Copyright © 2020 Sun, Zhang, Ross, Wang, Al-Chami and Wu.

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