The Cognitive and Behavioral Core will provide psychometric assessments of neuropsychological functions for all projects.  In addition, this Core will provide complementary support in the following two synergistic domains: (1) design, analysis, and development of novel cognitive neuropsychological tasks that will be used to assess the functionality ofthe fronto-striatal circuits impacted by Parkinson's disease (PD) and its treatment, and (2) neurocomputational and mathematical models of the fronto-striatal circuits for feedbackdriven reinforcement learning and neuro-economic decision making.  These models will inform the development of new behavioral tasks and will provide behavioral measures to inform the analysis of the brain imaging data collected from these tasks.