Dynamic changes in Anterior Cingulate Cortex ensembles mark the transition from exploration to exploitation

The ability to acquire knowledge about the value of stimuli or actions factors into simple foraging behaviors as well as complex forms of decision making. The anterior cingulate cortex (ACC) is thought to be involved in these processes, although the manner in which neural representations acquire value is unclear. Here we recorded from ensembles of ACC neurons as rats learned which of 3 levers was rewarded each day through a trial and error process. Action representations remained largely stable during exploration, but there was an abrupt, coordinated and differential change in the representation of rewarded and nonrewarded levers by ACC neurons at the point where the rat realized which lever was rewarded and began to exploit it. Thus, rather than a gradual, incremental process, value learning in ACC can occur in an all-or-none manner and help to initiate strategic shifts in forging behavior.