Fixation suppression of the vestibulo-ocular reflex (VOR) during sinusoidal stimulation in humans as related to the performance of the pursuit system.

Fixation suppression (FS) of the vestibulo-ocular reflex (VOR) was tested during passive sinusoidal body rotation with a frequency of 0.1 to 1.0 Hz and stimulus amplitudes ranging from 10 degrees to 240 degrees. To test whether FS can be explained by an internal pursuit signal opposite to the VOR, pursuit and the VOR under different instructional sets were studied. Both pursuit and FS decrease with increasing frequency and stimulus amplitude and seem to be limited by stimulus acceleration. Gains in FS calculated on the basis of the VOR during mental arithmetic correspond closely to the frequency and amplitude dependent pursuit gain, suggesting that an internal pursuit signal plays a major role in VOR suppression.