Abstract
The neural substrate of the perception of visual motion has been generally attributed to so-called "dorsal visual pathway", which includes the Medial Temporal Visual Area (MT) and several parietal regions. Recent studies, however, have revealed that the perception of a global feature of visual motion can require contribution of visual areas outside the dorsal pathway, such as superior temporal sulcus and fusiform gyrus for perception of biological motion. When hundreds of dots move in straight trajectories and random directions without colliding, the trajectories are perceived as wriggling rather than straight. In the present study, we used this Wriggling Motion Trajectory Illusion to investigate the neural correlates underlying perception of the "wrigglingness." In the experiment, 16 subjects observed visually presented moving stimuli under two conditions in Siemens 3T MRI scanner. In both conditions, dots moved straight in random directions. In the wriggling condition, dots moved without colliding, eliciting wriggling perception. In the control condition, the moving dots were allowed to collide and were perceived to be moving straight. BOLD signal changes were compared between the wriggling and the control conditions. The results indicated that illusory perception of wrigglingness coincided with activations in the temporal areas including bilateral fusiform gyrus and right inferior temporal gyrus. Our results also suggest that activities in the ventral visual pathway could modulate perception of motion trajectory. We conclude that perception of WMTI is, like perception of biological motion, based on transformation of motion-defined shape by moving dots.
Meeting abstract presented at VSS 2015