CONTRIBUTION OF SPINO-VESTIBULAR PATHWAYS TO GAZE STABILIZATION AND FUNCTIONAL RECOVERY AFTER LESION

Vestibular disorders affect millions of individuals in Europe, profoundly degrading their quality of life. While vestibular reflexes are classically studied in passive conditions, their modulation during active behaviors—such as locomotion—remains poorly understood. Here, we demonstrate the critical role of spino-vestibular coupling in vestibular physiology and post-lesion plasticity in awake mice.

Using video-oculography, we quantified gaze stabilization reflexes during passive rotation and during locomotion, combined with vestibular and visual stimuli. Before the lesion, locomotion significantly enhanced vestibulo-ocular reflex (VOR) performance: slow-phase gain increased by ~50% during vestibular stimulation in darkness and in visuo-vestibular conditions (frequencies < 1 Hz), while the occurrence of quick-phases increased across all paradigms. Notably, these improvements were uncorrelated with arousal (pupil size metrics) but positively correlated with locomotion intensity (speed and frequency).

To assess plasticity, we induced partial vestibular lesions using IDPN, a hair cell toxin. In lesioned animals, VOR deficits observed in passive conditions were partially rescued during locomotion, providing direct evidence that spino-vestibular signals participate in vestibular compensation. These findings reveal a dynamic, behavior-dependent modulation of vestibular reflexes and highlight a novel target for rehabilitative strategies.