Risk and Reward Perception in the Human Brain

The recent spate of neuroimaging studies on decision-making under uncertainty has provided converging evidence of a spatio-temporal dissociation of risk and expected reward encoding in the human brain. While this research has demonstrated widespread hemodynamic responses in a broad, non-homogeneous neural network, the roles of the di§erent loci have not been fully established. In addition, complications arise in elucidating the neural underpinnings of risk and reward perception due to the existence of multiple dopaminergic pathways as well as distinct afferent inputs into the subcortical striatum. The cortico-striatal connectivity is suggestive of a complex dynamics of DA neurons in the modulation of risk- and expected-reward related Blood Oxygenation Level Dependent (BOLD) responses in the striatum. The corresponding functional interpretation of striatal-level activities ought, therefore, to be different from that implied by the direct dopaminergic projections from the midbrain into the striatum. In this paper, evidence on the spatial-temporal separation of reward and risk signals is reviewed and a framework for integrating behavioral and neurophysiological data is proposed.