Abstract
The process of evaluating risks and benefits involves a complex neural network that includes the dorsolateral prefrontal cortex (DLPFC). It has been proposed that in conflict and reward situations, theta-band (4–8 Hz) oscillatory activity in the frontal cortex may reflect an electrophysiological mechanism for coordinating neural networks monitoring behavior, as well as facilitating task-specific adaptive changes. The goal of the present study was to investigate the hypothesis that theta-band oscillatory balance between right and left frontal and prefrontal regions, with a predominance role to the right hemisphere (RH), is crucial for regulatory control during decision-making under risk. In order to explore this hypothesis, we used transcranial alternating current stimulation, a novel technique that provides the opportunity to explore the functional role of neuronal oscillatory activities and to establish a causal link between specific oscillations and functional lateralization in risky decision-making situations. For this aim, healthy participants were randomly allocated to one of three stimulation groups (LH stimulation/RH stimulation/Sham stimulation), with active AC stimulation delivered in a frequency-dependent manner (at 6.5 Hz; 1 mA peak-to-peak). During the AC stimulation, participants performed the Balloon Analog Risk Task. This experiment revealed that participants receiving LH stimulation displayed riskier decision-making style compared to sham and RH stimulation groups. However, there was no difference in decision-making behaviors between sham and RH stimulation groups. The current study extends the notion that DLPFC activity is critical for adaptive decision-making in the context of risk-taking and emphasis the role of theta-band oscillatory activity during risky decision-making situations.
Highlights
When facing risky situations humans have to weigh up the consequences of failure against the rewards for success
The dorsolateral prefrontal cortex (DLPFC) has been considered to play an important role in decision-making under risk, probably due to its function in executive control, goal maintenance, and inhibitory control (Miller and Cohen, 2001; Knoch et al, 2006; Rao et al, 2008; Hare et al, 2009), as well as decision implementation (Mohr et al, 2010). This hypothesis seems plausible for right hemisphere (RH) role in risky decision-making under risk (“RH hypothesis”), and mostly pronounced in right PFC/DLPFC function as found in patients with right-sided lesions (Tranel et al, 2002; Clark et al, 2003), and is supported by several neuroimaging, EEG, and brain stimulation studies, and by a recent meta-analysis (Mohr et al, 2010)
The data from the Balloon Analog Risk Task (BART) task was analyzed with a mixed AVOVA model that included one between-subject factor and one within-subject factors
Summary
When facing risky situations humans have to weigh up the consequences of failure against the rewards for success. Assessing risk inevitably involves a conflict between the desire to win and the fear of penalty In such situations, the ability to identify and weight risks and benefits is highly important in order to make proper predictions concerning potential outcomes that will best serve individual survival and future goals. Studies of patients with focal brain lesion (e.g., Bechara et al, 1994, 1996; Tranel et al, 2002), alongside numerous neuroimaging and electroencephalogram (EEG) studies (e.g., Rogers et al, 1999; Paulus et al, 2001; Sanfey et al, 2003a,b; Ernst and Paulus, 2005; Trepel et al, 2005; Krain et al, 2006; Rao et al, 2008; Gianotti et al, 2009; Hare et al, 2009; Mohr et al, 2010) suggest that decision-making processes involve a distributed subcortical–cortical network that includes multiple prefrontal, parietal, limbic, and subcortical regions Within this network, prefrontal cortex (PFC) involvement appears to be vital in decision-making under risk. A repetitive transcranial magnetic stimulation (rTMS) study showed that individuals displayed riskier decision-making in a standard gambling paradigm after disruption of the right, but www.frontiersin.org
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