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Sustained eye closure slows saccades
BibTeX
@MISC{Shaikha_sustainedeye,
author = {Aasef G. Shaikha and Aaron L. Wongb and Lance M. Opticanc and Kenichiro Miurad and David S. Zeea},
title = {Sustained eye closure slows saccades},
year = {}
}
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Abstract
Saccadic eye movements rapidly orient the line of sight towards the object of interest. Pre-motor burst neurons (BNs) controlling saccades receive excitation from superior colliculus and cerebellum, but inhibition by omnipause neurons (OPNs) prevents saccades. When the OPNs pause, BNs begin to fire. It has been presumed that part of the BN burst comes from post-inhibitory rebound (PIR). We hypothesized that in the absence of prior inhibition from OPNs there would be no PIR, and thus the increase in initial firing rate of BNs would be reduced. Consequently, saccade acceleration would be reduced. We measured eye movements and showed that sustained eye closure, which inhibits the activity of OPNs and thus hypothetically should weaken PIR, reduced the peak velocity, acceleration, and deceleration of saccades in healthy human subjects. Saccades under closed eyelids also had irregular trajectories; the frequency of the oscillations underlying this irregularity was similar to that of high-frequency ocular flutter (back-to-back saccades) often seen in normal subjects during attempted fixation at straight ahead while eyes are closed. Saccades and quick phases of nystagmus are generated by the same pre-motor neurons, and we found that the quick-phase velocity of nystagmus was also reduced by lid closure. These changes were not due to a mechanical hindrance
Keyphrases
eye closure prior inhibition pre-motor burst neuron post-inhibitory rebound quick phase high-frequency ocular flutter peak velocity superior colliculus eye movement attempted fixation irregular trajectory normal subject quick-phase velocity bn burst healthy human subject saccade acceleration mechanical hindrance saccadic eye movement saccade receive excitation lid closure pre-motor neuron back-to-back saccade opns pause omnipause neuron
