Elicitation of Horizontal Nystagmus by Periodic Linear Acceleration

Abstract

Four subjects in each of four different body orientations were exposed to periodic linear acceleration stimuli produced by simple harmonic translation of 0.2, 0.4, and 0.8 cps cyclic frequency along an Earthhorizontal axis. Highly systematic horizontal nystagmus was demonstrated in response to these stimuli as well as to linear accelerations of rotating vector form equivalent to counterrotation in a constant magnitude linear force field. Vertical nystagmus could not be demonstrated for similar stimuli. The peak velocity of the slow component of nystagmus and the phase lag of the nystagmic response behind the linear acceleration stimulus were found to differ from those associated with periodic angular stimulation of the semicircular canals in a comparable frequency range. Regardless of stimulus form, the effective stimulus element for elicitation of horizontal nystagmus appeared to be dynamic change in the linear acceleration component directed along the subject's y (left-right) head axis.