Disambiguating action and valence in decision-making using pharmacology, computational models, and fMRI
Previous neurobiological research on decision-making has focused on the neural mechanisms of reward and punishment in the striatum and the substantia nigra/ventral tegmental area (SN/VTA). However, the functional organization of the striatum reflects its role in the generation of action and the control of action vigour. Our goal is to elucidate the impact of possible asymmetries between action and valence on affective decision-making at a behavioural, computational, and neurobiological level. In a series of experiments, we manipulated subjects’ requirement to emit or withhold an action independent from subsequent receipt of reward or avoidance of punishment. We show that at the neural level, action representations dominate over valence representations in the striatum and the SN/VTA and that action controls the dopaminergic enhancement of reward representations when dopamine levels are pharmacologically enhanced. We also show the existence of an asymmetric link between action and valence such as reward facilitates learning of active choices and punishment learning of passive choices. Finally, we show how this assymetric link between action and valence is differentially modulated by the dopaminergic and the serotonergic systems. Thus, our results point a need for an enriched account of opponency between reward and punishment in the dopaminergic system that includes notions of action control.
Part of the School of Psychology seminar series
Speaker: Dr Marc Guitart-Masip, Institute of Cognitive Neuroscience, University College London