hide
Free keywords:
-
Abstract:
When choosing between two actions, sensory evidence is accumulated toward one of the choices until a threshold is reached. Sensory neuron spike rate has been shown to track evidence accumulation. However, subjects will occasionally change their mind (switching from one action to the other), which is accompanied by a reversal in sensory neuron activity. It is unknown what neurons activate during a change-of-mind (CoM) potentially driving it. One candidate is anterior cingulate cortex (ACC), which has been shown in human EEG studies to respond around a CoM. Here, we for the first time directly report CoM in a rodent model. Head-fixed rats (N=43) were trained to discriminate stimuli by running on a treadmill past a distance threshold (Go) or remaining immobile (NoGo). On some NoGo stimulus trials, rats began running shortly after NoGo stimulus onset but made a CoM and chose to return to immobility before crossing the threshold. The time of CoM was defined by peak velocity of the treadmill, when the rat stopped running and began slowing down toward immobility. We tested the hypothesis that reversal from a higher velocity Go response to the NoGo response (immobility) would be associated with a larger ACC single unit response during the CoM. We recorded 574 ACC single units. On CoM trials, we found that stimulus-evoked responses of units tuned to the Go stimulus instead responded to the NoGo stimulus, suggesting engagement of the incorrect stimulus-response mapping in ACC. During the subsequent CoM, 20% of units scaled their activity with movement reversal size; moreover, a demixed PCA analysis showed that movement reversal size explained a large amount of variance in the population activity. Separately, 13% of units responded similarly but at the end of the trial and apparently quantified the magnitude of conflict between competing actions occurring earlier in the trial. In addition, whole-cortex 32-electrode EEG translationally linked rat and human CoM by identifying a frontal response during CoM. Our results support current theories that the ACC monitors past conflict between competing actions and significantly broaden the role for ACC by showing that ACC neurons may drive CoM.