A cortical area that responds specifically to optic flow, revealed by fMRI

The continuously changing optic flow on the retina provides information abo ut direction of heading and about the three-dimensional structure of the en vironment. Here we use functional magnetic resonance Imaging (fMRI) to demo nstrate that an area in human cortex responds selectively to components of optic flow, such as circular and radial motion. This area is within the reg ion commonly referrred to as V5/MT complex, but is distinct from the part o f this region that responds to translation. The functional properties of th ese two areas of the V5/MT complex are also different; the response to opti c flow was obtained only with changing flow stimuli, whereas response to tr anslation occurred during exposure to continuous motion.