'Disambiguating action and valence in decision-making using pharmacology, computational models, and fMRI'

Life and Environmental Sciences, Research
Tuesday 27th March 2012 (16:00-17:00)
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Speaker: Dr Marc Guitart-Masip, Institute of Cognitive, Neuroscience University College London

Previous neurobiological research on decision-making has focused on the neural mechanisms of reward andpunishment in the striatum and the substantia nigra/ventral tegmental area (SN/VTA). However, thefunctional organization of the striatum reflects its role in the generation of action and the control of actionvigour. Our goal is to elucidate the impact of possible asymmetries between action and valence on affectivedecision-making at a behavioural, computational, and neurobiological level. In a series of experiments, wemanipulated subjects’ requirement to emit or withhold an action independent from subsequent receipt ofreward or avoidance of punishment. We show that at the neural level, action representations dominate overvalence representations in the striatum and the SN/VTA and that action controls the dopaminergicenhancement of reward representations when dopamine levels are pharmacologically enhanced. We alsoshow the existence of an asymmetric link between action and valence such as reward facilitates learning ofactive choices and punishment learning of passive choices. Finally, we show how this assymetric linkbetween 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 thedopaminergic system that includes notions of action control.