Behavioral experiments indicate that central pathways that process otolith-ocular and perceptual information have adaptive capabilities. Because polarization vectors of otolith afferents are directly related to the electro-mechanical properties of the hair cell bundle, it is unlikely that they change their direction of excitation. This indicates that the adaptation must take place in central pathways. Here, we demonstrate for the first time that otolith polarization vectors of canal-otolith convergent neurons in the vestibular nuclei have adaptive capability. A total of ten vestibular-only (VO) and vestibular-plus-saccade (VPS) neurons were recorded extracellularly in two monkeys before and after the monkeys were in side-down positions for 2 hr. The spatial characteristics of the otolith input were determined from the response vector orientation (RVO), which is the projection of the otolith polarization vector, determined in head coordinates, onto the head horizontal plane. The RVO's had no specific orientation before animals were in side-down positions, but moved toward the gravitational axis after the animals were tilted for extended periods. Vector reorientations varied from 0º to 109º and were linearly related to the original deviation of the RVO's from gravity. Such reorientation of central polarizations vectors could provide the basis for changes in perception and eye movements related to prolonged head tilts relative to gravity or in microgravity.