Electrophysiological Characterization of Murine Vestibular Efferent Neurons and Modulation by Acute Peripheral Vestibular Deprivation.

Vestibular efferent neurons in the brainstem provide direct cholinergic innervation to peripheral vestibular organs, thereby modulating their sensory responsiveness. In this study, a genetically targeted mouse model with choline acetyltransferase-driven fluorescent labeling enabled the precise localization of these neurons to the dorsolateral region of the genu of the facial nerve. Whole-cell patch-clamp recordings in acute brainstem slices revealed that virtually all neurons exhibited spontaneous action potential firing, with marked heterogeneity in discharge patterns and after-hyperpolarization kinetics. Prominent A-type potassium currents were identified and found to be differentially regulated by acetylcholine and calcitonin gene-related peptide. Acute unilateral vestibular deprivation induced a bilateral enhancement of spontaneous firing, indicating sensitivity to altered sensory input. These findings define the intrinsic electrophysiological properties and neuromodulatory mechanisms of vestibular efferent neurons, providing mechanistic insight into their roles in both physiological regulation and adaptive plasticity within the vestibular system.