Abstract
One of the archetypal task manipulations known to depend on frontal-lobe function is reversal learning, where a dominant response must be overridden due to changes in the contingencies relating stimuli, responses, and environmental feedback. Previous studies have indicated that the lateral prefrontal cortex (LPFC), the lateral orbitofrontal cortex (LOFC), the anterior cingulate cortex (ACC), and the caudate nucleus (CN) all contribute to reversal learning. However, the exact contributions that they make during this cognitively complex task remain poorly defined. Here, using functional magnetic resonance imaging, we examine which of the cognitive processes that contribute to the performance of a reversal best predicts the pattern of activation within distinct sub-regions of the frontal lobes. We demonstrate that during reversal learning the LOFC is particularly sensitive to the implementation of the reversal, whereas the LPFC is recruited more generally during attentional control. By contrast, the ACC and CN respond when new searches are initiated regardless of whether the previous response is available, whilst medial orbitofrontal cortex (MOFC) activity is correlated with the positive affect of feedback. These results accord well with the hypothesis that distinct components of adaptable behaviour are supported by anatomically distinct components of the executive system.
Highlights
The ability to alter behaviour according to changes in the environment is important for the survival of any organism
Participants were asked to rate all the faces contained on the database using a computer based visual analogue scale (VAS)
In accordance with previous findings, our results implicate a network of frontal lobe and striatal brain regions in the reversal learning task
Summary
The ability to alter behaviour according to changes in the environment is important for the survival of any organism. It is well established that damage to the ventral prefrontal cortex leads to impairments in visual discrimination reversal learning in humans (Fellows and Farah, 2003; Hornak et al, 2004), monkeys (Dias et al, 1996; Iversen and Mishkin, 1970; Izquierdo et al, 2004) and rats (Chudasama and Robbins, 2003; Schoenbaum et al, 2002) This is mirrored by functional neuroimaging studies in humans that show a change in blood flow in a network of brain regions at the point in time when subjects first switch their responding following a reversal of the reward contingencies. The precise contributions of other regions outside of the ventral prefrontal cortex that have been implicated in visual discrimination reversal learning, in particular, the anterior cingulate cortex (ACC) and the caudate nucleus (CN) (Clarke et al, 2008; Cools et al, 2002; Rogers et al, 2000) remain unclear
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