Movement analysis and aVOR gain for: A) Normal chinchilla, B) chinchilla with bilateral vestibular hypofunction (lesioned) without prosthetic stimulation, C) same chinchilla after chronic constant-rate stimulation, and D) same chinchilla after chronic stimulation with modulation to head motion. Normal chinchilla exhibited normal aVOR (data from [4]) and no high frequency circling. Lesioned chinchilla initially exhibited high frequency circling, which disappeared after chronic modulation but not after chronic constant-rate stimulation. Angular VOR was absent in the lesioned chinchilla with the prosthesis powered off or with constant-rate stimulation, but was partially restored with prosthetic modulation. Asymmetry in gain is due to inherent limitations in encoding inhibitory head motions using a unilaterally-implanted prosthesis. All sinusoidal eye responses were measured at 2Hz, 100°/s in the dark. Although movements were recorded for at least 15 minutes in the dark, only a representative 1 minute sample is shown for purpose of clarity.