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Reinforcement learning in avoidance, habits, and tics| old_uid | 11616 |
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| title | Reinforcement learning in avoidance, habits, and tics |
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| start_date | 2012/07/13 |
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| schedule | 11h-12h |
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| online | no |
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| location_info | Amphi Charve |
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| summary | Learning to act so as to obtain rewards is well known to depend on phasic dopamine bursts. The role of dopamine in aversive contexts, in contrast, is poorly understood. I will use a reinforcement-learning model to show that actions that avoid aversive outcomes are also reinforced by phasic dopamine bursts. The model made several new predictions concerning the pattern of dopamine release during avoidance learning, and I will present a microdialysis study that confirmed the model’s predictions. I will then turn to the role of dopamine and reinforcement learning in Tourette’s syndrome (TS), a disorder characterized by motor and vocal tics. I will present an fMRI study that shows that TS is characterized by hyperactivity in motor portions of cortico–basal ganglia circuits and by both hyperactivity in dopamine-containing regions of the midbrain and excessive connectivity between those regions and the basal ganglia. One interpretation of these results is that the motor hyperactivity represents exaggerated motor habits, which may be reinforced by the dopamine hyperactivity. I will present a model-based fMRI study of habit learning in healthy controls that supports this interpretation. In that study, subjects that learned a habit engaged the same circuitry that was excessively active in the patients with TS; in contrast, subjects that failed to learn the habit did not engage that circuitry. I will conclude with some broader thoughts about the usefulness of integrating computational modeling and empirical techniques to advance our understanding of psychiatric and neurological disorders. |
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| responsibles | Pélissier |
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