Effects of electrode penetrations into the abducens nucleus of the monkey: Eye movement recordings and histopathological evaluation of the nuclei and lateral rectus muscles

J. R. McClung, K. E. Cullen, M. S. Shall, D. M. Dimitrova, S. J. Goldberg

Research output: Contribution to journalArticlepeer-review

Abstract

Two adult rhesus monkeys that had undergone 2 years of electrode penetrations into their abducens and vestibular nuclei, for chronic eye movement studies, were examined histologically. An analysis of their VIth nucleus neurons and lateral rectus muscles revealed the following. Twenty-two percent of the large neurons (≈30 μm in diameter), on average, were missing and extensive neuropil disruption and gliosis was evident in the experimental side abducens nuclei as compared with the control side in each animal. While the lateral rectus muscles showed small, but inconsistent, changes in total fiber number, the muscle fiber diameters were altered, leading to a more homogenous muscle and making the typical orbital and global subdivisions of the muscle less distinct. Eye movement records from before and after the electrophysiological studies were comparable. We discuss how the complex architecture of the extraocular muscles as well as the possibility of polyneuronal innervation of single muscle fibers could explain our results.

Original languageEnglish (US)
Pages (from-to)180-188
Number of pages9
JournalExperimental Brain Research
Volume158
Issue number2
DOIs
StatePublished - Sep 2004
Externally publishedYes

Keywords

  • Abducens nucleus
  • Lateral rectus muscle
  • Motoneuron
  • Polyneuronal innervation

ASJC Scopus subject areas

  • Neuroscience(all)

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