Hemispheric asymmetries in tracking occluded moving targets with the mind's eye: Simultaneous event-related fMRI and eye-movement recording

The ability of the eyes and brain to predict and track visible and occluded moving targets is essential to goal-directed action. Event-related functional MRI and eye-movements were simultaneously measured during a smooth pursuit task with different levels of visual cuing. Subjects tracked a white dot moving from left to right following a sinusoidal pattern, during which it could be seen over half the screen (visible condition) before disappearing behind the occlusion bar (occluded condition). When tracking occluded, moving targets, we observed a hemisphere asymmetry at the early visual cortex, but not in motion-processing area MT/V5. During eye-tracking, the left early visual cortex responded stronger than the right to visible targets, but the right responded stronger to occluded targets. In contrast, motion-processing area MT/V5 in both hemispheres favored visible over occluded targets. These results suggest the right early visual cortex is the mind's eye, receiving input from higher level memory regions to produce simulated vision during occlusion.