Abstract
Message of gravity is transformed into the senses of the gravitational "up" and a force that pulls things "down" by the vestibular system. Little is known about whether and how such information is integrated with other sensory cues in conscious perception. It has been documented that visual gravitational motion can activate the vestibular cortex where the internal model of gravity is stored. However, the influence of vestibular state on visual perception has been scarcely investigated. Here we examined whether long-term change of vestibular state may alter the activity of visual cortices using -6[sup]0[/sup] head-down bed rest, an approach widely used to simulate weightlessness. We recorded, both before and after 45 days of bed rest, observers’ neural responses to upright and inverted biological motion, face and house stimuli, as well as their brain activities in the resting state. Significant drop of neural inversion effect (NIE) in the pSTS for biological motion was found after bed rest, but not for faces in the FFA, or for houses in the PPA, suggesting that long-term vestibular state change modulates visual processing that specifically involves gravitational motion. More importantly, the change observed in the pSTS was not evident in the MT and FBA that are respectively dedicated to basic motion and static body perception, implying a specialized mechanism tuned to the processing of biological motion per se. Brain connectivity analyses further showed a significant correlation between the change of connectivity from vestibular cortex to pSTS and the change of biological motion perception following the bed rest. These findings provide clear evidence that the change of vestibular state alters the visual responses to gravitational biological motion information, thus broadening our understandings of the vestibular contribution to conscious perception.
Meeting abstract presented at VSS 2013