Left hemispheric unbalance and reward mechanisms affect gambling behavior. The contribution of the metacognition, SCR and cortical brain oscillations

In general subjects choose their decisional strategy based on the estimated outcomes, in many cases mainly taking into account the long-term effects, since they learn to select the advantageous strategy across time. It was shown that pathological gambling is associated with deficits in frontal lobe functioning, and that this dysfunctional decisional strategy shows features similar of patients with bilateral VMPFC (Ventromedial Prefrontal Cortex) lesions since they prefer choices that bring immediate reward, although they are losing. The present research tested the effect of reward-sensitivity (BAS-Reward, Behavioral Activation System) construct on the ability to distinguish between high- and low-risk decisions by using IOWA Gambling Task. In order to elucidate the individual differences which influence the decisional processes, making them more or less advantageous, we considered the impact of BAS-Reward, of the frontal left and right cortical activity, of the SCR (Skin Conductance Response) and of the metacognitive skills, on subjects’ decisions. More specifically, the lateralization effect, related to the increased activation of the left (BAS-Reward-related) hemisphere, was explored by using frequency band analysis. Thirty subjects were grouped in high-BAS and low-BAS group. Behavioral responses (gain/loss options, response Index, rI), pshychophysiological measure of SCR, and delta, theta, alpha and beta band modulation (asymmetry index) were considered. Moreover, sLORETA method was used to localise the source of neural activity in response to gain/loss options. It was found that high-BAS group increased the tendency to opt in favour of the immediate reward (losing strategy) more than the long-term option (winning strategy), and that high-BAS subjects showed an increased left-hemisphere activation when they responded to losing choices in comparison with low-BAS subjects. Dorsolateral prefrontal cortex and anterior cingulate cortex were found to differentiate the high-BAS vs low-BAS brain activity. In addition, no significant SCR modulation was observed for high-BAS group in response to losing strategy, in contrast to the low-BAS group. Finally, high-BAS subjects were unable to adequately represent their cognitive strategy. A “reward bias” effect was supposed to act for high-BAS, based on a left-hemisphere over-activation.