Functional neuroanatomy of cognition in Parkinson's disease.

While cognitive dysfunction in Parkinson's disease (PD) is increasingly recognized as a progressive symptom of the underlying neurodegenerative disease, our understanding of the functional and structural anatomic changes underlying these cognitive changes remains incomplete. Like the motor system, research point to a complex interplay between multiple parallel yet interconnected networks or circuits that are affected in PD and give rise to cognitive symptomatology. These circuits are most often studied in the context of disorders of executive function, and tightly linke to frontal lobe dysfunction. While the tasks employed vary across studies and it is often unclear whether differences in anatomy and function are causal or compensatory, the literature points to several key circuits that seem to be uniquely impaired in PD patients with cognitive dysfunction. This chapter reviews four of these circuits including the frontostriatal, frontoparietal, mesocortical, and noradrenergic circuits. By gaining a better understanding of the functional neuroanatomy of these circuits, we begin to develop a more comprehensive and unifed picture of how they to account for the pathophysiology of cognitive dysfunction in PD.