Heading direction perception in the horizontal plane is strongly driven by rotational stimuli in healthy and impaired in vestibular hypofunction

Self-motion perception relies on the central integration of vestibular, visual and proprioceptive sensory inputs into a coherent percept of self-motion. To better understand the central integration of linear and rotational stimuli, we examined rotational and translational movements in the horizontal plane in healthy subjects (HS) and in patients with unilateral vestibular hypofunction (pwUVH). We established a novel heading discrimination paradigm using a motion platform to examine heading direction perception for translational movements with additional yaw rotations of - 1°, 0°, or 1°. We examined 26 HS and 26 pwUVH. Heading direction perception in HS and pwUVH was strongly driven by rotational stimuli. Among HS, adding 1° of yaw rotation to a translational movement resulted in an average shift of perceived straight-ahead translations to the opposite side of 2.15° (yaw to the right) and 2.30° (yaw to the left) respectively. pwUVH showed significantly higher discrimination thresholds (right UVH +3.3°, left UVH +6.4°) across all conditions than HS. We show that vestibular guided self-motion perception is strongly influenced by rotational movements, supporting central canal-otolith integration hypothesis. Self-motion perception is significantly impaired towards both sides in patients with unilateral vestibular hypofunction.