Characterization of the decision-making deficit of patients with ventromedial prefrontal cortex lesions

On a gambling task that models real-life decisions, patients with bilateral lesions of the ventromedial prefrontal cortex (VM) opt for choices that yi eld high immediate gains in spite of higher future losses, In this study, w e addressed three possibilities that may account for this behaviour: (i) hy persensitivity to reward; (ii) insensitivity to punishment; and (iii) insen sitivity to future consequences, such that behaviour is always guided by im mediate prospects. For this purpose, we designed a variant of the original gambling task in which the advantageous decks yielded high immediate punish ment but even higher future reward. The disadvantageous decks yielded low i mmediate punishment but even lower future reward. We measured the skin cond uctance responses (SCRs) of subjects after they had received a reward or pu nishment. Patients with VM lesions opted for the disadvantageous decks in b oth the original and variant versions of the gambling task. The SCRs of VM lesion patients after they had received a reward or punishment were not sig nificantly different from those of controls. In a second experiment, we inv estigated whether increasing the delayed punishment in the disadvantageous decks of the original task or decreasing the delayed reward in time disadva ntageous decks of the variant task would shift the behaviour of VM lesion p atients towards an advantageous strategy, Both manipulations failed to shif t the behaviour of VM lesion patients away from the disadvantageous decks. These results suggest that patients with VM lesions are insensitive to futu re consequences, positive or negative, and are primarily guided by immediat e prospects. This 'myopia for the future' in VM lesion patients persists in the face of severe adverse consequences, i.e. rising future punishment or declining future reward.