Fig. 6.

Gain and phase of the chinchilla translational vestibulo-ocular reflex (tVOR) during lateral and surge translations. A and B: frequency sweep results during lateral (A) and surge translations (B) at 0.2–3 Hz recorded from 5 normal chinchillas. Gain is reported as the position of angular eye position in degrees divided by the equivalent tilt of the gravitation vector due to the linear acceleration [equivalent tilt = arctan(acceleration/gravity)] and plotted on a log-log scale. Steady state sinusoidal phase was calculated as the difference between peak head position and peak eye position. Negative phase indicates eye position lags head acceleration. Error bars depict one standard deviation from the mean values of either gain or phase. Lateral translations elicit a primary roll component of tVOR with a gain around 0.2; all gains decrease as frequency increases. The roll component leads head acceleration by 90° while yaw lags the head by −90 to −180°. The pitch components between both eyes are disconjugate, as expected from the equivalent head tilt theory of interpretation for tVOR. Surge translations elicit approximately equal roll and pitch gain at low frequencies, showing a decline of all gains as frequency increased. Phase values indicate disconjugate yaw and roll components while pitch was conjugate throughout all frequencies.