It was noticeable, therefore, that the comparison of GENERATE+MONITOR with either GENERATE or FIXED+MONITOR in Walton et al. (2004) did not show any increases in activity in the OFC. However, a separate contrast in this fMRI study was also run comparing where in the brain the signal at the time of switch was greater in FIXED+MONITOR compared to in GENERATE+MONITOR, corresponding to the regions concerned with monitoring the outcome of an action that had been externally instructed rather than internally generated, and this comparison did reveal OFC activations (Figure 4a). Such a finding concurs with studies reporting that activity in the OFC can occur in response to reward or a break in expectation even when there is no requirement to make a decision (Berns, McClure, Pagnoni and Montague, 2001; Nobre, Coull, Frith and Mesulam, 1999; O'Doherty, Dayan, Friston, Critchley and Dolan, 2003; Petrides, Alivisatos and Frey, 2002). Again, there was no difference in the signal in FIXED+MONITOR following correct or incorrect feedback. Comparing the activity in the ACC and OFC in these two monitoring conditions showed an interesting functional coupling
