Neuronal reward mechanisms. (360G-Wellcome-058365_Z_99_C)

a) For scientifically qualified assessors. We aim to localise and investigate brain mechanisms related to rewards and goal-directed behaviour. Rewards constitute appetitive outcomes and are prime motivating factors for selecting and initiating behavioural acts. Convergent lines of evidence suggest that the basal ganglia and frontal cortex are important for the control of voluntary, goal-directed behaviour and the processing of rewarding outcomes. We will study the impulse activity of single neurons in animal models during specific behavioural tasks leading to reward. We would like to investigate: (i) how midbrain dopamine neurons are activated in relation to attention and higher order processing of reward information, in four different experiments. We know so far that dopamine neurons signal the discrepancy between the prediction and occurrence of rewards (reward prediction error), a crucial measure for reward-directed learning. (ii) how the expectation of different reward quantities is processed in the striatum (caudate nucleus, putamen, ventral striatum). Reward quantity represents a straightforward measure for motivational value of goal objects and crucially determines behavioural reactions and choices. (iii) how reward information is incorporated into mechanisms related to the decision, selection and initiation of goal-directed behaviour in striatum and prefrontal cortex. We particularly like to see how reward information is reflected in behaviour-related brain activity while the choices occur prior to reward. We will relate this to the spontaneous initiation of reward-directed behaviour. b) For readers who are not scientifically qualified. Some of the principal functions of brain activity concern the production of mental states and goal-directed behaviour in response to environmental events. The reception of sensory stimuli and the organisation of movements have been widely investigated. However, we know much less how the brain processes information about goals for behaviour, and how that information is integrated into the neuronal control of behaviour. Rewards constitute typical goals for behaviour. Which parts of the brain process information about rewards, and how exactly is this done by individual neurons? We know that some neurons in the frontal cortex and striatum, and many dopamine neurons, change their activity when a light or tone indicates that a piece of fruit or a drop of juice will be available in a few seconds. But how do these neurons process further information about rewards that is necessary for behavioural decisions, such as the magnitude of rewards or the attention aroused by rewards? How does the brain process representations of rewards which are not yet or no longer present in the environment? How are information about rewards used when decisions and choices lead to useful, reward-directed actions? These are the kind of questions we would like to answer. This research also relates to problems of public health, as drugs of abuse most likely exert their effects on the brain's reward mechanisms.