UNASSIGNED: Although anatomically well described, the functional role of the @entity1 efferent vestibular system (EVS) remains unclear. Unlike in fish and reptiles, the @entity1 EVS does not seem to play a role in modulation of primary afferent activity in anticipation of active head movements. However, it could play a role in modulating long-term mechanisms requiring plasticity such as vestibular adaptation. We measured the efficacy of vestibulo-ocular reflex (VOR) adaptation in a9-knockout @entity19 . These @entity19 carry a missense mutation of the gene encoding the a9 nicotinic @entity934 receptors (nAChRs) subunit. The a9- @entity15683 subunit is expressed in the vestibular and auditory periphery, and its loss of function could compromise peripheral input from the predominantly-cholinergic EVS. We measured the VOR gain (eye-velocity/head-velocity) in 26 a9-knockout @entity19 and 27 cba129 controls. @entity19 were randomly assigned to one of three groups: gain-increase adaptation (x1.5), gain-decrease adaptation (x0.5) or no adaptation (baseline, x1). Following adaptation training, (horizontal rotations at 0.5Hz with peak-velocity 20  /s) we measured the sinusoidal (0.2-10Hz, 20-100  /s) and transient (1500-6000  /s(2)) VOR in complete darkness. a9-knockout @entity19 had significantly lower baseline gains compared to control @entity19 . This difference increased with stimulus frequency (~5%<1Hz to ~25%>1Hz). Moreover, vestibular adaptation (difference in VOR gain of gain-increase and gain-decrease adaptation groups as a percentage of gain-increase) was significantly reduced in a9-knockout @entity19 (17%) compared to controls (53%), a reduction of ~70%. Our results show that the loss of alpha9-nAChRs moderately affects the VOR, but severely affects VOR adaptation, suggesting the EVS plays a crucial role in vestibular plasticity.

The XXXX efferent vestibular system plays a crucial role in the high-frequency response and short-term adaptation of the vestibulo-ocular reflex.

@entity1 :: ('9606', 'Species') :: ['mammalian'] @entity15683 :: ('11441(Tax:10090)', 'Gene') :: ['nAChR'] @entity19 :: ('10090', 'Species') :: ['mice', 'Mice'] @entity934 :: ('MESH:D000109', 'Chemical') :: ['acetylcholine']
@entity1 :: (9606,Species) :: ['mammalian']
