On error trials, DMS neurons in control rats fired similarly for responses to be made into and away from the response field, suggesting that, on error trials, DMS failed to form an appropriate motor plan (Fig. 3B; gray dashed line). In the lesion group, DMS firing also failed to represent the appropriate action but also fired significantly more strongly for errant responses in the direction cued by the first light, presumably driving behavior in the incorrect direction (Fig. 3C). Tick marks indicating significant differences between thick and thin gray dashed lines (t tests every 100 ms; P < 0.01) in the population demonstrate that the average firing was significantly stronger in lesioned rats for errant behaviors made into the response field. Notably, errant selectivity emerged prior to illumination of the second cue light (Fig. 3C), suggesting that ACC contributes to the dampening of the firing that prevents errant responses in the likelihood that the second cue might be presented. This issue is further addressed in the following section.
