Beraneck M, McKee JL, Aleisa M, Cullen KE. Asymmetric recovery in cerebellar-deficient mice following unilateral labyrinthectomy. J Neurophysiol 100: 945-958, 2008. First published May 28, 2008 doi:10.1152/jn.90319.2008. The term "vestibular compensation" refers to the resolution of motor deficits resulting from a peripheral vestibular lesion. We investigated the role of the cerebellum in the compensation process by characterizing the vestibuloocular reflex (VOR) evoked by head rotations at frequencies and velocities similar to those in natural behaviors in wild-type (WT) versus cerebellardeficient Lurcher (Lc/ϩ) mice. We found that during exploratory activity, normal mice produce head rotations largely consisting of frequencies Յ4 Hz and velocities and accelerations as large as 400°/s and 5,000°/s 2 , respectively. Accordingly, the VOR was characterized using sinusoidal rotations (0.2-4 Hz) as well as transient impulses (ϳ400°/s; ϳ2,000°/s 2 ). Before lesions, WT and Lc/ϩ mice produced similar VOR responses to sinusoidal rotation. Lc/ϩ mice, however, had significantly reduced gains for transient stimuli. After unilateral labyrinthectomy, VOR recovery followed a similar course for WT and Lc/ϩ groups during the first week: gain was reduced by 80% for ipsilesionally directed head rotations on day 1 and improved for both strains to values of ϳ0.4 by day 5. Moreover, responses evoked by contralesionally directed rotations returned to prelesion in both strains within this period. However, unlike WT, which showed improving responses to ipsilesionally directed rotations, recovery plateaued after first week for Lc/ϩ mice. Our results show that despite nearly normal recovery in the acute phase, long-term compensation is compromised in Lc/ϩ. We conclude that cerebellar pathways are critical for longterm restoration of VOR during head rotation toward the lesioned side, while noncerebellar pathways are sufficient to restore proper gaze stabilization during contralesionally directed movements.