Figure 4.

Model of global and selective inhibitory control. (A) Global suppression. Standard stopping causes suppression (gray arrows) across the motor cortex, affecting the task-irrelevant legs in both Experiments 1 and 3 (downward pointing black arrows in boxes indicate reduced excitability). (B) Selective suppression. Stopping selectively while continuing an alternative movement likely involves an alternative mechanism in which suppression is only directed toward the effector in question. However, there is also leg suppression on the same side as the continuing hand, which is significant only in Experiment 2. We suggest that this may be the signature of a different mechanism associated with making the continuing movement (rather than stopping), that is, intrahemispheric hand–arm surround inhibition. (C) Global-suppression-plus-reinitiation alternative model. Global suppression (gray arrows in left panel) is subsequently masked by activation from reinitiating the continuing hand (black arrows in right panel), which only affects the leg representation of the opposite hemisphere and spares that of the same hemisphere.