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Grands Séminaires du Collège de France :“Learning and organizing new action repertoires”| old_uid | 9889 |
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| title | Grands Séminaires du Collège de France :“Learning and organizing new action repertoires” |
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| start_date | 2011/04/29 |
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| schedule | 16h |
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| online | no |
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| location_info | salle 2 |
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| details | accès public |
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| summary | Organism behavior can be organized as sequences of particular actions. Deciding when to initiate and terminate a particular sequence of actions, or when to switch to a different behavior is critical for survival. We used a self-paced operant task in which mice were trained to perform a particular sequence of lever presses to obtain an outcome, and verified that mice learned to perform specific sequences of lever presses. Furthermore, we recorded the neural activity in nigrostiatal circuits during action sequence learning and found neural activity specifically signaling the initiation and termination of sequences of actions in putative striatal medium spiny neurons, and nigral dopaminergic and GABAergic neurons. This start/stop selective activity emerged during sequence learning, was specific for particular actions, and did not seem to reflect interval timing or differences in expected action value at the beginning and end of a sequence. We uncovered that a striatal-specific genetic deletion of NMDA receptors selectively impairs the development of this start/stop activity and sequence learning. Next, we developed a task where mice need to perform a specific action sequence very rapidly, close to the timescale of human speech and birdsong (a limited-time fixed-ratio differential reinforcement schedule). We recorded the activity in striatum and downstream target regions of direct pathway neurons (Substantia nigra pars reticulata -SNr) and indirect pathway neurons (Globus pallidus external GPe). We found that activity in SNr and GPe diverged during the learning of ultrafast sequences, with the activity in each nuclei relating differently to the initiation and termination of sequences, or the execution of the whole sequence. Finally we used optogenetic tools to indentify the activity of direct and indirect pathway striatal neurons during different the execution of ultrafast sequences. These data have important implications for understanding the learning and execution of action sequences, and the impairments observed in basal ganglia disorders like Parkinson’s and Huntington’s disease. |
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| responsibles | Maloumian |
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