Left. In habitual condition (HC), performances are optimal, with or without GPi. In novel condition (NC), only the intact model (with GPi) is able to learn the new stimuli while lesioned model performances stay at the level f chance. Right. Analysis of the data shows that reaction time is higher in normal condition as compared to habitual condition with active and inactive GPi. The later increases significantly the reaction time in both conditions. All data have been averaged over 250 simulations.