Neurobiological processes during the Cambridge gambling task

Abstract

Although vast research has been conducted concerning gambling behavior this is the first study combining behavioral and functional magnetic resonance imaging (fMRI) data while using the Cambridge Gambling Task (CGT). We tested 20 healthy right-handed men and chose an event-related design to allow for precise temporal separation of gambling stages. In the color decision stage participants had to guess whether a yellow token was hidden behind red or blue boxes presented in varying color ratios, then stake wagers during the bet decision stage. In the final stage the outcome (won or lost) was presented. Analyzing the blood-oxygenation level-dependent (BOLD) contrasts in the decision stages we found increases of activation in brain areas involved in decision making, working memory and learning, when participants bet on the majority choice. During the outcome stage increased brain activation was found in parts of the reward system and areas involved in decision making and impulse control, when winning. When losing, activation increased in areas involved in risk aversion and management of uncertainties. When participants lost unexpectedly (i.e. lost although they bet on the majority), increased activation was found in the insula, compared to winning expectedly. The more unexpectedly participants won the higher the increase of brain activation in parts of the reward system and areas involved in executive functions. Our study gives an extensive overview of brain areas involved in different stages of gambling and during various outcomes, with corresponding behavioral data (e.g. speed and quality of decision making) illustrating underlying tendencies.

Keywords: Addiction; Decision making; Gambling; Risk taking; fMRI.