Article révisé par les pairs
Résumé : This study aimed to examine neural anticipation of monetary reward in pathological gamblers (PG) by varying the type of uncertainty associated with high-uncertain rewards. Ten PG and ten controls were scanned while deciding whether to accept ("bet" option, featuring high-uncertain monetary rewards) or reject ("safe" option, featuring low-certain rewards) a bet within situations of decision-making under risk (probability of the "bet" reward is known) or ambiguity (probability of the "bet" reward is unknown). During decision under risk (as compared to ambiguity), controls exhibited activation in brain areas involved in the reward processing (putamen), in interoception (insula) and in cognitive control (dorsolateral prefrontal cortex; middle frontal gyrus). In contrast, PG exhibited no differential brain activation as a function of the type of uncertainty associated with the "bet" option. Moreover, prior choosing of the "safe" option (as compared with "bet" choices), controls exhibited activation in the posterior insula, dorsolateral prefrontal cortex and middle frontal gyrus. In contrast, PG exhibited higher neural activation during the elaboration of "bet" choices and in motivational-arousal areas (caudate; putamen; posterior insula). Between-group contrasts revealed that, as compared to controls, PG showed (i) decreased neural activity in the globus pallidus for decision-making under risk as opposed to decision under ambiguity, and (ii) increased neural activity within the putamen prior to bet choices as opposed to safe choices. These findings suggest that (i) unlike control participants, a variation in the level of uncertainty associated with monetary rewards seems to have no significant impact on PG's decision to gamble and (ii) PG exhibit stronger brain activation while anticipating high-uncertain monetary rewards, as compared with lower safe rewards.

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