The contribution of ventrolateral and dorsolateral prefrontal cortex to response reversal

Studies investigating response reversal consistently implicate regions of medial and lateral prefrontal cortex when reinforcement contingencies change. However, it is unclear from these studies how these regions give rise to the individual components of response reversal, such as reinforcement value encoding, response inhibition, and response change. Here we report a novel instrumental learning task designed to determine whether regions implicated in processing reversal errors are uniquely involved in this process, or whether they play a more general role in representing response competition, reinforcement value, or punishment value in the absence of demands for response change. In line with previous findings, reversal errors activated orbitofrontal cortex, dorsomedial prefrontal cortex, ventrolateral prefrontal cortex, caudate, and dorsolateral prefrontal cortex. These regions also showed increased activity to errors in the absence of contingency changes. In addition, ventrolateral PFC, caudate, and dorsolateral PFC each exhibited increased activity following correct reversals. Activity in these regions was not significantly modulated by changes in reinforcement value that were not sufficient to make an alternative response advantageous. These data do not support punishment-processing or prepotent response inhibition accounts of ventrolateral prefrontal cortex function. Instead, they support recent conceptualizations of ventrolateral prefrontal cortex function that implicate this region in resolving response competition by manipulating the representation of either motor response options, or object features. These data also suggest that dorsolateral prefrontal cortex plays a role in reversal learning, probably through top down attentional control of object or reinforcement features when task demands increase. (C) 2007 Elsevier B.V. All rights reserved.