Representation of visual gravitational motion in the human vestibular cortex

How do we perceive the visual motion of objects that are accelerated by gravity? We propose that, because vision is poorly sensitive to accelerations, an internal model that calculates the effects of gravity is derived from graviceptive information, is stored in the vestibular cortex, and is activated by visual motion that appears to be coherent with natural gravity. The acceler-ation of visual targets was manipulated while brain activity was measured using functional magnetic resonance imaging. In agreement with the inter-nal model hypothesis, we found that the vestibular network was selectively engaged when acceleration was consistent with natural gravity. These find-ings demonstrate that predictive mechanisms of physical laws of motion are represented in the human brain. The perception of motion is a fundamental property of the visual system. One of the most frequently encountered stimuli is an object accelerated by gravity, as in free-fall, ballis