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Ignacio Obeso

THE ROLE OF THE BASAL GANGLIA IN RESPONSE INHIBITION : EVIDENCE FROM SURGERY FOR PARKINSON DISEASE

Centre de Recherche en Neurosciences de Lyon

It has been proposed that the basal ganglia play a key role in selection of appropriate responses using its inhibition and response thresholds mechanisms. Indeed, the subthalamic nucleus (STN) has shown consistent evidence to be the principal actor of response inhibition. The aim of the presentation will be to present current hypotheses that the STN and the internal capsule of the globus pallidum (GPi) provide differential roles in (i) reactive and proactive inhibition, (ii) conflict resolution and (iii) adjusting response thresholds. These were addressed by comparing behavioral and imaging results of patients with Parkinson’s disease (PD) treated with unilateral subthalamotomies and deep brain stimulation (DBS) when performing a conditional stop signal task. The conditional stop signal task requires response inhibition but also conflict resolution in another condition. These different conditions also provide a measure of proactive inhibition to adapt to both contexts (difference in RTs between both conditions). Results show a direct involvement of the right STN when inhibiting inappropriate actions by altering its quality because of a change in response threshold adjustment. Moreover, DBS of the STN also alters such behaviors. Thus, the STN seems to be a key candidate region for controlling and stopping behaviors in patients with PD.