Separating sustained from transient aspects of cognitive control during thought suppression.

Cognitive theories of how people regulate their thoughts have suggested the involvement of two control processes that occur over different time courses. These cognitive accounts parallel recent neural models of executive control, which suggest that the prefrontal cortex (PFC) mediates sustained changes in the allocation of control processes, whereas the anterior cingulate cortex (ACC) relays a transient need for additional control. Combining these cognitive and neural models of control, we used recently developed analysis techniques to distinguish transient from sustained changes in brain activation while subjects attempted to suppress an unwanted thought. Results were consistent with both models: Dorsolateral PFC demonstrated sustained increases in activation during attempts at thought suppression, whereas bilateral ACC demonstrated transient increases associated with occurrences of unwanted thoughts. These data support proposals regarding the different contributions made by the PFC and ACC to executive control and provide initial neuroimaging support for dual-process models of how individuals regulate their thoughts.