Summary: Sheth et al. (2012)

One of the major components to human cognition is the ability to behave in the most appropriate manner to constantly changing environmental pressure. Cognitive control is regulated by the dorsal anterior cingulate cortex (dACC). This has been proposed to play a role in reward-based decision making, conflict resolution between two competing responses and assessment/prediction of the difficulty of a task. Sheth et al. (2012) used functional imaging and human single-neuron recordings to show the precise mechanisms of dACC function, indicating that individual dACC neurons encode cognitive load (recent and current). They further show that prior activity modifies current dACC activity to produce a behavioural adaptation that speeds up reactions to cues previously experienced as difficult, but can slow reactions to cues with different difficulties (known as the Gratton effect). Sheth et al.'s (2012) results show that future behavioural responses can be optimized by the continuous updating of predictions of expected cognitive demand by the dACC. They further suggest that in stable conditions, efficiency is promoted by speeding up responses, but when conditions become variable or unstable, accuracy is improved through the delay of responses.