Abstract
Prefrontal cortex plays an important role in decision making (DM), supporting choices in the ordinary uncertainty of everyday life. To assess DM in an unpredictable situation, a playing card task, such as the Iowa Gambling Task (IGT), has been proposed. This task is supposed to specifically test emotion-based learning, linked to the integrity of the ventromedial prefrontal cortex (VMPFC). However, the dorsolateral prefrontal cortex (DLPFC) has demonstrated a role in IGT performance too. Our aim was to study, by multichannel near-infrared spectroscopy, the contribution of DLPFC to the IGT execution over time. We tested the hypothesis that low and high risk choices would differentially activate DLPFC, as IGT execution progressed. We enrolled 11 healthy adults. To identify DLPFC activation associated with IGT choices, we compared regional differences in oxy-hemoglobin variation, from baseline to the event. The time course of task execution was divided in four periods, each one consisting of 25 choices, and DLPFC activation was distinctly analyzed for low and high risk choices in each period. We found different time courses in DLPFC activation, associated with low or high risk choices. During the first period, a significant DLPFC activation emerged with low risk choices, whereas, during the second period, we found a cortical activation with high risk choices. Then, DLPFC activation decreased to non-significant levels during the third and fourth period. This study shows that DLPFC involvement in IGT execution is differentiated over time and according to choice risk level. DLPFC is activated only in the first half of the task, earlier by low risk and later by high risk choices. We speculate that DLPFC may sustain initial and more cognitive functions, such as attention shifting and response inhibition. The lack of DLPFC activation, as the task progresses, may be due to VMPFC activation, not detectable by fNIRS, which takes over the IGT execution in its second half.
Highlights
There is a general agreement in the role of the prefrontal cortex in decision-making (DM), under conditions of complexity and unpredictability (e.g., Bechara et al, 2000a; Bechara, 2001; Clark et al, 2003; Wise, 2008; Gläscher et al, 2012)
A significant dorsolateral prefrontal cortex (DLPFC) activation emerged with low risk choices, whereas, during the second period, we found a cortical activation with high risk choices
We used multichannel near-infrared spectroscopy (NIRS) to study if DLPFC is differentially activated, over time, by low or high risk choices during the execution of the complete administration of Iowa Gambling Task (IGT), a playing card task developed to study decision making (DM) under uncertainty
Summary
There is a general agreement in the role of the prefrontal cortex in decision-making (DM), under conditions of complexity and unpredictability (e.g., Bechara et al, 2000a; Bechara, 2001; Clark et al, 2003; Wise, 2008; Gläscher et al, 2012). In order to assess the complex nature of human DM under uncertainty, the Iowa Gambling Task (IGT) has been developed (Bechara et al, 1994). It is a playing card task which simulates real-life decisions. VMPFC may play a role in the continuous updating of expectations about reward and punishment based on experience (Fellows and Farah, 2005; Oya et al, 2005; Stocco and Fum, 2007)
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