The modulation component of nystagmus during earth-horizontal rotation: relationship with gaze angle.

Periodic fluctuations in gaze angle and nystagmus slow phase velocity (SPV) were characterized using 6 normal subjects rotated at constant angular velocity about their rostral-caudal body axis with that axis in the horizontal orientation. The periodicity of the fluctuations corresponded to the angular frequency of rotation. The magnitude of the SPV fluctuations was moderately well correlated with those of the gaze fluctuations. Four vector quantities were found to characterize these data fairly completely, yet compactly.