More dopamine (DRD2)

Genetic triple dissociation reveals multiple roles for dopamine in reinforcement learning:

...Here, we show with genetic analyses that three independent dopaminergicmechanisms contribute to reward and avoidance learning in humans.A polymorphism in the DARPP-32 gene, associated with striataldopamine function, predicted relatively better probabilisticreward learning. Conversely, the C957T polymorphism of the DRD2gene, associated with striatal D2 receptor function, predictedthe degree to which participants learned to avoid choices thathad been probabilistically associated with negative outcomes.The Val/Met polymorphism of the COMT gene, associated with prefrontalcortical dopamine function, predicted participants' abilityto rapidly adapt behavior on a trial-to-trial basis. These findingssupport a neurocomputational dissociation between striatal and prefrontal dopaminergic mechanisms in reinforcement learning. Computational maximum likelihood analyses reveal independent gene effects on three reinforcement learning parameters that can explain the observed dissociations.

Related: Strange behavioral days?.