Although our results strongly suggest that impairment of ACC function negatively impacts the ability to reactively modulate response selection at both the behavioral and the neural levels, alternative explanations should be considered. First, it might be argued that ACC lesions result in a decrease in the willingness to exert effort (2, 23). This interpretation seems unlikely because control and lesioned rats performed the same total number of trials (t(724) = 1.011, P = 0.3123), and latencies to initiate trials did not significantly differ (t(724) = 0.6124, P = 0.5405), suggesting that rats from both groups displayed similar levels of motivation and effort. Another possibility would be that rats are just better at GO trials after lesions, thus making inhibition and redirection to the second light more difficult. This seems unlikely given that accuracy on GO trials did not significantly differ between groups and previous recordings show that firing in ACC is relatively weak on GO trials (11). This result also suggests that basic motor functions remain intact. A third possibility is that ACC lesions impact mechanisms of arousal or attention.
