Implications of Ewald's second law for evaluation of vestibular function.
ABSTRACT The significance of Ewald's second law in the evaluation of the vestibulo-ocular reflex (VOR) was investigated using the transfer characteristics of the vestibular and VOR systems in normal rabbits and rabbits in which one horizontal semicircular canal had been blocked. The transfer characteristics of the vestibular system were derived from the experimental results reported by Goldberg and Fernández in 1971. A comparison was made of the properties of the bilateral and monolateral VOR systems with the predictions of a piecewise linear model of the vestibular system. The data received quantitatively collaborate the prediction of Ewald's second law as it applies to the VOR responses.
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ABSTRACT: Measurements were made of the lesion-induced changes in vestibulo-ocular reflexes to rotatory stimuli in a group of patients with total unilateral labyrinthine paralysis and in a group with partial unilateral labyrinthine paralysis. Significant differences were found in the amplitude and phase of the response to low-frequency rotation and in the time constant of the post-rotatory response to impulsive rotation between normal subjects and patients with total unilateral labyrinthine paralysis. The results were evaluated by the use of a simplified model of vestibular function that allows the parametric evaluation of the characteristics of vestibular responses. It was found that changes in vestibulo-ocular reflex characteristics take place in parallel in both the time constant and the sensitivity of the system parameters used to describe the responses. The physiologic significance of the changes and their implication for diagnostic purposes are discussed.American Journal of Otolaryngology 01/1984; 5(1):15-26. DOI:10.1016/S0196-0709(84)80016-2 · 1.08 Impact Factor