Impairment of recovery from incentive downshift after lesions of the anterior cingulate cortex: emotional or cognitive deficits?

The anterior cinculate cortex (ACC) is known to be implicated in pain-fear and reward expectations. Animals were given electrolytic lesions of the ACC and then trained in the consummatory successive negative contrast (cSNC) situation. In cSNC, animals exposed to an incentive downshift from 32% to 4% sucrose exhibit less consummatory behavior than animals always exposed to 4% sucrose. The ACC lesion had no measurable effects on the consummatory performance of animals before the downshift (i.e., the lesion did not affect consumption of 32% vs. 4% sucrose); on the performance of unshifted, 4% sucrose animals; and on the first downshift trial. However, ACC animals exhibited a significant retardation of recovery from cSNC relative to downshifted shams. Within-trial analysis of consummatory behavior indicated that ACC lesions facilitated cSNC during both the initial and last 100 s of postshift trials after the first downshift experience, relative to sham controls. These results suggest that the ACC is part of the neural circuit normally involved in coping with the emotional response induced by the incentive downshift event by inducing learning of the new incentive conditions.