Dopamine/Serotonin interaction in reward-related behavior: Focus on the Iowa Gambling Task

Abstract

The Iowa Gambling Task (IGT) is a tool to study decision making behavior. Subjects choose cards from four decks; choosing a card will result in gain or loss of money and subjects are instructed to gain as much money as possible at the end of the task. Two decks result in immediate high gains, but in the long run result in substantial losses, whereas the other two decks provide moderate immediate gains, however, choosing from these two latter decks will provide a positive balance in the long run. Both subcortical and cortical substrates are involved in decision making during the IGT. A cortico-striatal circuit, encompassing the NAC, amygdala and several areas of the PFC subserves this behavior. Within this circuit, the different components are more or less involved with the different components that are involved in the task. Whereas the subcortical areas may be more involved in coding reward magnitude and assigning affect to certain stimuli, the cortical areas appear to be more important for coding stimulus-reward contingencies and adapting behavior when following a long term strategy. Ventral and medial PFC areas and their associated dopaminergic circuitry are more involved in the first half of the IGT, when subjects show no clear preference for a particular deck but choose cards from decks randomly. (Dorso)lateral PFC areas and their associated serotonergic circuitry appear to be more important during the later stages of the IGT, when subjects have formed preferences for certain decks over others. In this thesis, I will describe how dopamine and serotonin may interact during the IGT