Effect of aging on the otolith-ocular reflex.
We assessed the influence of age on the otolith-ocular reflex and semicircular canal-otolith interaction. Healthy young (n=30) and healthy older (n=60) subjects were rotated about an earth vertical axis, and about a 30 degree off-vertical axis. Eye movements during and following rotation were recorded using electro-oculography. Results indicated that there were statistically significant changes in the otolith-ocular reflex and semicircular canal-otolith interaction as a function of age. The modulation component during off-vertical axis rotation (OVAR) was greater in the older group compard to the young adults, whereas the bias component was smaller with advanced age. The foreshortening of the vestibulo-ocular reflex time constant induced by post-rotatory head tilt following cessation of rotation was less prominent in the older group. There were no consistent changes in the semicircular canal-ocular reflex. Overall, response parameters showed more variability in the older subjects. We conclude that age related changes in the otolith-ocular reflex and semicircular canal-otolith interaction are a result primarily of a degradation of central vestibular processing of otolith signals rather than a decline of peripheral vestibular function.
Furman
J M
JM
Department of Otolaryngology, University of Pittsburgh, The Eye and Ear Institute, PA 15213, USA. furman@pitt.edu
Redfern
M S
MS
D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D005260:Female; D018475:Head-Down Tilt; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010037:Otolithic Membrane / Q000502:physiology*; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology*; D012399:Rotation; D012665:Semicircular Canals / Q000502:physiology