A model of dual control mechanisms through anterior cingulate and prefrontal cortex interactions

A computational model is presented that describes dual mechanisms of cognitive control through interactions between the prefrontal cortex (PFC) and anterior cingulate cortex (ACC). One mechanism, reactive control, consists in the transient activation of PFC, based on conflict detected in ACC over a short time-scale. The second mechanism, proactive control, consists in the sustained active maintenance of task-set information in a separate PFC module, driven by long time-scale conflict detected in a separate ACC unit. The computational function of the first mechanism is to suppress the activation of task-irrelevant information just prior to when it could interfere with responding. The role of the second mechanism is to prime task-relevant processing pathways prior to stimulus-onset, in a preparatory fashion. The model provided an excellent fit to both the behavioral and brain imaging data from a previous detailed empirical study on humans performing the color-word version of the Stroop task. The model captured changes in reaction times across conditions, accuracy, and transient and sustained activity dynamics within lateral PFC and ACC. (c) 2006 Elsevier B.V. All rights reserved.