The role of serotonin in risky choice and the acquisition of reciprocal cooperative behaviour: 2 investigations using tryptophan depletion

.Making decisions between risky actions involves weighing the pros and cons of each, and considering the relative probabilities with which good and bad outcomes will occur. In this paper, I review 2 recent studies suggesting that serotonin modulates the cognitive and emotional processes involved in such decision-making in both non-social and social contexts. First, we have found that tryptophan depletion – leading to diminishes central serotonin activity – alters attention towards the gains associated with risky options. Second, we have found that tryptophan depletion alters the acquisition of socially cooperative behaviour in an iterated Prisoner's Dilemma game. These findings highlight the significance of serotonin in altered non-social and social risky choice in psychiatric illnesses.