title: Eye-head coordination and lateral canal block in squirrel monkeys.
abstract: Eye and head nystagmus during horizontal optokinetic stimulation was analyzed in squirrel monkeys. Slow phase speed of coupled head and eye nystagmus showed highly significant negative correlations in normal subjects; correlation coefficients were -0.81 at 60 degrees/sec and -0.72 at 100 degree/sec stimuli. Bilateral semicircular canal block resulted in a reduction of the negative correlation. The postoperative reduction of the correlation coefficient value ranged from 0.17-0.28 (significant at P less than 0.01 level) at 60 degrees/sec stimulus and 0.06-0.13 (non significant) of 100 degrees/sec stimulus. Gaze speed was calculated by summing slow phase speeds of coupled head and eye nystagmus. Mean error of gaze in normal subjects was 1.5% at 60 degrees/sec stimulus and 7.8% at 100 degrees/sec stimulus. Mean gaze speed showed an overshoot (8% at 60 degrees/sec stimulus and 6.5% at 100 degrees/sec stimulus) in the tree to four weeks postoperative period; however, this subsided two to three months after the operation. Measurement of head-turning performance (in yaw plane) in humans may provide a clinically useful index for the assessment of certain types of vestibular function.
mesh_terms: D000818:Animals; D004584:Electronystagmography; D005133:Eye Movements; D006257:Head / Q000502:physiology*; D009068:Movement; D012453:Saimiri; D012665:Semicircular Canals / Q000502:physiology*; D014726:Vestibular Nuclei / Q000502:physiology