A NEURONAL MODEL OF A GLOBAL WORKSPACE IN EFFORTFUL COGNITIVE TASKS

A minimal hypothesis is proposed concerning the brain processes underl ying effortful tasks. It distinguishes two main computational spaces: a unique global workspace composed of distributed and heavily intercon nected neurons with long-range axons, and a set of specialized and mod ular perceptual, motor, memory, evaluative, and attentional processors , Workspace neurons are mobilized in effortful tasks for which the spe cialized processors do not suffice. They selectively mobilize or suppr ess, through descending connections, the contribution of specific proc essor neurons. In the course of task performance, workspace neurons be come spontaneously coactivated, forming discrete though variable spati o-temporal patterns subject to modulation by vigilance signals and to selection by reward signals. A computer simulation of the Stroop task shows workspace activation to increase during acquisition of a novel t ask, effortful execution, and after errors. We outline predictions for spatio-temporal activation patterns during brain imaging, particularl y about the contribution of dorsolateral prefrontal cortex and anterio r cingulate to the workspace.