When moving through space, for instance by walking or driving a vehicle, our brain processes several sensory inputs that inform us about the properties of our motion to accomplish successful spatial navigation. Sensory inputs as visual and auditory tell us how we move with respect to the surroundings whilst vestibular sensory information provides a reference of self-motion with respect to gravity. The vestibular system is composed by the semicircular canals and otolith organs that signal rotational and linear acceleration of the head respectively. Such vestibular inputs are combined with the other sensory modalities to provide coherent perception of gravity and self-motion. In this context, psychophysical methods have been used to investigate the interaction of sensory modalities such as vision, haptic and audition with vestibular. Perception of verticality indicates how the system processes gravity thus it represents an indirect measurement of vestibular perception. Head tilts can lead to biases in perceived verticality interpreted as the influence of a vestibular prior set at the most common orientation relative to gravity (i.e., upright), useful By conducting studies on the perception of verticality across development and in the presence of blindness, we observed that crossmodal aftereffect paradigms which test whether adaptation in one sensory modality induces biases in another, eventually revealing an interconnection between the tested sensory modalities. Our studies showed that visual adaptation leads to vestibular aftereffects and vestibular adaptation induces aftereffects in auditory motion perception. Altogether, such interactions across sensory modalities reveal the presence of multisensory neural mechanisms that constantly function to calibrate self-motion dedicated sensory modalities with each other as well as with the environment.
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