Patients’ apparent failure to increase frontoparietal connectivity appropriately in response to the B cue may reflect difficulty recruiting key elements of the neural network required to implement cognitive control. This is consistent with the observed correlations between connectivity and task performance. In control subjects, greater connectivity between dorsal cingulate and prefrontal cortex in the B cue condition was associated with slower B cue RTs. It is thought that dorsal cingulate activity signals the need for engagement of cognitive control processes mediated by lateral prefrontal regions (69–71). This signal typically initiates when task performance elicits conflict. Higher conflict is associated with greater task difficulty and a greater need for strategic control (72,73). One prediction of this view is that cingulofrontal connectivity should be highest when task difficulty is high, indexed by increased conflict and an increased need for cognitive control. Our results accord with this prediction, because healthy individuals who found B trials more difficult, as reflected by relatively slower RTs, showed greater cingulofrontal connectivity during these trials. This association between connectivity and behavior was not present in the patient group,
