Reward system, metacognitive control and ERP effect in gambling behavior

Recent studies showed that pathological gambling is associated with deficits in frontal lobe function and that pathological gambler subjects used to opt in favour of immediate reward, without considering the long-term outcomes like patients with bilateral VMPFC lesions or addictive disorders. Many previous researches tested the ability to distinguish between high- and low-risk decisions and the learning effect based on previous experiences by a typical decisional task such as the Iowa Gambling Task (IGT). Considering specific ERP effects like the feedback negativity (FRN) and the P300, frequently used to explore the impairment of the executive functions in decisional processing, the aim of this study was to analyze behavioral responses, meta-cognitive strategies, and ERP (FRN and P300) effects which are supposed to be predictive markers of gambling behavior. It was also supposed that high-BAS (high Behavioral Activation System) subjects, who generally are more reward-related, should show inability in monitoring reward predictor errors mainly in case of loss options: specifically we expected the absence of FRN increased amplitude in response to negative outcomes and a substantial equivalence of the P300 amplitude in response to gains and losses. BAS-reward measure was applied to distinguish between high-BAS and low-BAS traits in twenty-two healthy subjects (ten women, age range 19-25, M = 23.78). They were instructed to IGT and the EEG was recorded during he task, measuring left, central and right frontal (F3, Fz, F4), middle-central (Cz, C3, C4), temporo-parietal (P3/T7, Pz, P4/T8) and occipital (Oz, O1, O2) brain activity. After this session a questionnaire was applied to test the general self- knowledge of the cognitive strategy adopted. Results showed a significant decreased IGT rI Index for high-BAS than low-BAS, since the former were focused on the immediate reward (losing long-term strategies). Moreover the high-BAS group showed a significant decreased self-representation of a planned strategy, flexibility, and efficacy. According to the ERP effect related to feedback monitoring (FRN) and attentional mechanisms (P300), the high-BAS group in comparison with the low-BAS showed a significant reduction of the classical “enhanced effect” in response to unattended feedback. Moreover, sLORETA analysis showed that the cortical source for FRN effect was localized over the Dorsolateral Prefrontal Cortex and the ACC, while for P300 the effect was on the Superior Temporal Gyrus. Thus, deficiencies concerning feedback mechanisms were apparent in those individuals extremely focalized on reward (reward bias) if compared to individuals who did not base their decisions on immediate reward. In conclusion it is possible to consider reward salience as an important aspect in feedback processes in subjects with high-risky attitudes.