Elsevier

Hearing Research

Volume 149, Issues 1–2, November 2000, Pages 91-105
Hearing Research

Effects of deafferentation on the electrophysiology of ventral cochlear nucleus neurons1

https://doi.org/10.1016/S0378-5955(00)00165-9Get rights and content
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Abstract

When cochlear pathology impairs the afferent innervation of the ventral cochlear nucleus (VCN), electrical responses of the auditory brainstem are altered and changes in cell and synaptic morphology are observed. However, the impact of deafferentation on the electrical properties of cells in the VCN is unknown. We examined the electrical properties of single neurons in the anterior and posterior VCN following bilateral cochlear removal in young rats. In control animals, two populations of cells were distinguished: those with a linear subthreshold current–voltage relationship and repetitive firing of action potentials with regular interspike intervals (type I), and those with rectifying subthreshold current–voltage relationships and phasic firing of 1–3 action potentials (type II). Measures of action potential shape further distinguished these two groups. Two weeks following cochlear removal, both electrical response patterns were still seen. Type I cells showed a higher input resistance. Deafferented single-spiking type II cells were slightly more depolarized, had smaller action potentials, smaller afterhyperpolarizations and shorter membrane time constants, whereas multiple-spiking type II cells were apparently unaffected. These changes in the electrical properties of VCN neurons following cochlear injury may adversely affect central processing of sounds presented acoustically or electrically by prostheses.

Keywords

Deafferentation
Cochlear ablation
Deafness
Ventral cochlear nucleus
Intracellular recording
Discharge pattern
Brain slice

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1

Abstracts of this work were previously presented at the American Academy of Otolaryngology-Head and Neck Surgery meeting, San Francisco, CA, USA, 1997, and the 21st Midwinter Meeting of the Association of Research in Otolaryngology, St. Petersburg, FL, USA, 1998.

2

Present address: Division of Otolaryngology/Head and Neck Surgery, Department of Surgery, 610 Burnett-Womack Bldg., CB#7070, The University of North Carolina, Chapel Hill, NC 27599-7070, USA.