On STOP-change trials, rats were significantly slower to respond and were less accurate (Fig. 1 D and E). Presumably, this is because neural signals related to encoding response direction first represent the direction associated with the first cue, which then must be inhibited or changed, so that activity reflecting the second light can emerge and behavior can be redirected. Indeed, this is exactly what we see in the neural signals recorded in DMS; that is, when the first and second cue are presented into and away from the response field (Fig. 2B, thin red line), respectively, DMS firing first increases in response to the first light and then decreases in response to the second light. The opposite pattern was observed when the first and second cues were presented into and away from the response field, respectively (Fig. 2B, thick red line). Importantly, resolution of the directional signal preceded the estimated time necessary to redirect behavior [STOP-change reaction time (SCRT) = STOP minus GO movement times; gray dashed line] on correct trials as previously reported (12) (Fig. 2B).
