Spatiotemporal phase-scrambling increases visual cortex activity.

The hemodynamic response of the visual cortex to continuously moving spatial stimuli of virtual tunnels and phase-scrambled versions thereof was examined using functional magnetic resonance imaging. Earlier functional magnetic resonance imaging studies found either no difference or less early visual cortex (VC) activation when presenting normal versus phase-manipulated static natural images. Here we describe an increase in VC activation while viewing phase-scrambled films compared with normal films, although basic image statistics and average local flow were the same. The normal films, in contrast, resulted in an increased lateral occipital and precuneus activity sparing VC. In summary, our results show that earlier findings for scrambling of static images no longer hold for spatiotemporal stimuli.