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What you get is what you see: How Reward Determines Perception

Final Report Summary - REWARDVIEW (What you get is what you see: How Reward Determines Perception)

The expectation of receiving a reward is considered to be the driving force behind all adaptive behaviour and learning. It is known that the dopaminergic reward circuitry at the centre of our primitive brain plays a crucial role in goal-directed behaviour. We have shown that that reward (and the expectation of receiving a reward) not only plays a crucial role in motivational control but also affects the way we perceive the world around us. Indeed, if attending to an object is followed by a large reward, that object becomes visually more attractive, more salient than when attending to that very same object is followed by a small reward. We claim that the reward-related activity in the dopamine system changes the sensory representation in the visual system such that the features of the objects that were rewarded appear to be more salient than non rewarded features. The dopamine (DA) system plays a crucial role in mediating a broad array of rewarding activities, be it candy, sex, drugs or music. When we perform an action that is followed by a rewarding state of affairs, the neurotransmitter dopamine is released and produces pleasure. It serves as a signal that the action promotes survival or reproduction, directly or indirectly. This system is called the reward pathway.
In this ERC project we investigated how reward changes the ‘settings’ in our brain, thereby altering the way we perceive the world around us. We related the response of the dopaminergic reward brain circuitry. We have shown that the effect of reward on perception and attention is large and robust and that learning reward contingencies only occurs when observers attend the relevant features. Crucially, once established these effects of reward on perception and attention become mandatory, i.e. once an object is associated with a high reward we cannot help attending it. It grabs our attention and our eyes even if we try to ignore these objects, similar to what is seen in those who are suffering for substance abuse. We investigated reward learning in Parkinson patients who are known to have reduced levels of dopamine. We show that there was a negative learning rate which was predictive of medication-induced changes in approach and avoidance behavior, as well as changes in corresponding brain activity in the striatum. We have shown that psychopathic patients who show a lack of affective reactivity to rewarding or threatening events have trouble incorporating contextual information related to the task at hand. We have shown that the size of the pupil responses reflects dynamics of behavioural control related to value-based learning. The results indicate that the size of the pupil signals reward-based learning on separate timescales. We speculate that this measure may be a proxy of the dopaminergic response in the brain underlying this pupillary value response.