This description of ACCs function differs to an extent to those suggesting that this region signals alterations in outcome that in turn drives changes in behaviour as the ACCs-lesioned animals appeared unimpaired at updating their choices (Bush, Vogt, Holmes, Dale, Greve, et al., 2002; Shima and Tanji, 1998). Such ideas are based in part on reports of the effects of muscimol injections into part of the ACCs which caused difficulties on a reward-guided switching task where animals learned to switch between two movements on the basis of a reduction in the amount of reward received (Shima and Tanji, 1998). However, while the authors stress the fact that the monkeys were poor at using reward reductions to change their responses following inactivation of the ACCs, close inspection of the manuscript shows that these animals would also at times fail to persist with a rewarded response just like the monkeys with ACCs lesions in Kennerley and colleagues' study, prematurely switching away to the alternative movement. This suggests that both deficits may be better explained as a failure to learn and/or maintain an ongoing long-term representation of the value of actions rather than one specifically concerned with behavioural alterations.
