Effect of tolcapone on brain activity during a variable attentional control task: a double-blind, placebo-controlled, counter-balanced trial in healthy volunteers.

Background: Attention is the capacity to flexibly orient behaviors and thoughts towards a goal by selecting and integrating relevant contextual information. The dorsal cingulate (dCC) and prefrontal (PFC) cortices play critical roles in attention. Evidence indicates that catechol-O-methyltransferase (COMT) modulates dopaminergic tone in the PFC and dCC.