Different modulation of medial superior temporal activity across saccades: a functional magnetic resonance imaging study.

Studies on saccadic eye movements in humans and animals reported decreased cortical activation accompanying saccades in visual motion sensitive area MT+/V5, implying that the region is the neural basis of saccadic suppression. This, however, conflicts with findings that MT+/V5 is activated by saccades. As MT+/V5 can be subdivided into middle temporal (MT) and medial superior temporal (MST), these regions may have distinct functional roles that cause the discrepancy. To test this hypothesis, we compared the activation of MT with that of MST during exploratory saccades and visually guided saccades. MST was activated only during visually guided saccades, whereas MT was not activated by either. These findings support our hypothesis and suggest that the activity of these regions is differentially modulated depending on extraretinal information.