The effects of ion channel blockers validate the conductance-based model of saccadic oscillations

Aasef G. Shaikh, David Samuel Zee, Lance M. Optican, Kenichiro Miura, Stefano Ramat, R. John Leigh

Research output: Contribution to journalArticle

Abstract

Conductance-based models of reciprocally inhibiting burst neurons suggest that intrinsic membrane properties and postinhibitory rebound (PIR) determine the amplitude and frequency of saccadic oscillations. Reduction of the low-threshold calcium currents (I T) in the model decreased the amplitude but increased the frequency of the simulated oscillations. Combined reduction of hyperpolarization-activated cation current (I h) andI T in the model abolished the simulated oscillations. We measured the effects of a selective blocker ofI T (ethosuximide) in healthy subjects on the amplitude and frequency of saccadic oscillations evoked by eye closure and of a nonselective blocker ofI h andI T (propronolol) in a patient with microsaccadic oscillation and limb tremor syndrome (mSOLT). Ethosuximide significantly reduced the amplitude but increased the frequency of the saccadic oscillations during eye closure in healthy subjects. Propranolol abolished saccadic oscillations in the mSOLT patient. These results support the hypothetical role of postinhibitory rebound,I h, andI T, in generation of saccadic oscillations and determining their kinematic properties.

Original languageEnglish (US)
Pages (from-to)58-63
Number of pages6
JournalAnnals of the New York Academy of Sciences
Volume1233
Issue number1
DOIs
StatePublished - Sep 2011

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Keywords

  • Burst neurons
  • Hyperpolarization-activated cation current
  • Low-threshold calcium current
  • Reciprocal innervations

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • History and Philosophy of Science

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