Is the hMT+/V5 complex in the human brain involved in stereomotion perception? An fMRI study

Binocular disparity is one of the most powerful sources of depth information. Stereomotion is motion-in-depth generated by disparity changes. This study is focused on the hMT+/V5 complex, which is known to support both motion and disparity processing in primates. Does the motion-complex process stereomotion as well? BOLD functional magnetic resonance imaging (fMRI) was used. The fMRI contrasts of stereomotion vs stationary stimuli, as well as lateral non-stereoscopic motion vs stationary stimuli, showed strong fMRI activation of the motion complex. Direct contrasts of stereomotion vs different types of lateral-motion also revealed differential activity but in a restricted subregion of the motion complex, suggesting a distinct stereomotion-selective neuronal subpopulation within it. No consistent activation was found for the stimuli viewed non-stereoscopically. The stereomotion-specific locus revealed within the hMT+/V5 complex contributes to the understanding of stereomotion.