Decision-making involves evaluating the costs and benefits of available options for action. Many psychiatric disorders involve a disruption of decision-making processes. Application of concepts derived from instrumental learning theories, computational models, and fMRI (functional Magnetic Resonance Image) technology has allowed identification of key neuronal substrates of these processes. A key control influence is mediated by dopamine transmission, vie its modulatory influences on the striatum and prefrontal areas. Work using experimental animals has drawn an accurate picture of the neuronal mechanisms that regulate dopamine transmission including an important effect elicited by novelty. The objective of the project is to deepen in the understanding of the behavioral and neurological interrelationships of dopamine neurotransmission, novelty processing and decision-making in humans. To achieve this goal we will use computational models in conjunction with brain imaging technologies, specifically fMRI and MEG (Magnetoencephalograpy). In a first step, we will address the human brain’s response to different aspects of novelty and how this is mediated by dopamine. In a second step we will focus on the effect of different kinds of novelty in decision making during probabilistic gambling from a behavioral and brain imaging perspective. Finally, in a third step we will try to understand the effect of pharmacological manipulations upon probabilistic decision making from a behavioral and neurobiological perspective. Results obtained within this project will inform how humans make decisions under uncertainty, and how novelty influences choice behaviour. Understanding how critical brain computations are implemented in the human brain will also inform an understanding of psychiatric disorders where aberrant novelty processing may reflect a fundamental component such as attention deficit disorder (ADHD).