A Large-scale Neurocomputational Model of Task-oriented Behavior Selection and Working Memory in Prefrontal Cortex
Journal of Cognitive Neuroscience
Prefrontal cortex is crucially involved in the executive component of working memory, representation of task state, and behavior selection. This paper presents a large-scale computational model of prefrontal cortex and associated brain regions designed to investigate the mechanisms by which working memory and task state interact to select adaptive behaviors from a behavioral repertoire. The model consists of multiple brain regions containing neuronal populations with realistic physiological and
... c physiological and anatomical properties, including extrastriate visual cortical regions, inferotemporal cortex, prefrontal cortex, striatum, and midbrain dopamine neurons. The onset of a delayed match-to-sample or delayed non-match-to-sample task triggers tonic dopamine release in prefrontal cortex causing a switch into a persistent, stimulusinsensitive dynamic state that promotes the maintenance of stimulus representations within prefrontal networks. Other modeled prefrontal and striatal units select cognitive acceptance or rejection behaviors according to which task is active and whether prefrontal working memory representations match the current stimulus. Working memory task performance and memory fields of prefrontal delay units are degraded by extreme elevation or depletion of tonic dopamine levels. Analyses of cellular and synaptic activity suggest that hypo-normal dopamine levels result in increased prefrontal activation, while hyper-normal dopamine levels lead to decreased activation. Our simulation results suggest a range of predictions for behavioral, single-cell, and neuroimaging response data under the proposed task set and under manipulations of dopamine concentration.