Chemogenetics reveal an anterior cingulate-thalamic pathway for attending to task-relevant information

In a changing environment, we need to decide when to select items that resemble previously rewarded stimuli and when it is best to switch to other stimulus types. Here, we used chemogenetic techniques to provide causal evidence that activity in the rodent anterior cingulate cortex and its efferents to the anterior thalamic nuclei modulate the ability to attend to reliable predictors of important outcomes. Rats were tested on an attentional set-shifting paradigm that first measures the ability to master serial discriminations involving a constant stimulus dimension that reliably predicts reinforcement (intradimensional-shift), followed by the ability to shift attention to a previously irrelevant class of stimuli when reinforcement contingencies change (extradimensional-shift). Chemogenetic silencing of the anterior cingulate cortex (Experiment 1) as well as selective inactivation of anterior cingulate efferents to the anterior thalamic nuclei (Experiment 2) impaired intradimensional learning but, facilitated two sets of extradimensional-shifts. This pattern of results signals the loss of a cortico-thalamic system for cognitive control that preferentially processes stimuli resembling those previously associated with reward. Previous studies highlight a separate prefrontal system that promotes switching to hitherto inconsistent predictors of reward when contingencies change. Competition between these two systems regulates cognitive flexibility and choice.