Beta oscillations in the cortico-basal ganglia loop during parkinsonism

In the normal brain beta band oscillatory activity has been associated with retaining of ongoing motor activities. In Parkinson's disease, enhanced beta band oscillatory activity is displayed across the cortico-basal ganglia pathway and is one of the prominent neurophysiological phenomena associated with the disorder. Intraoperative and postoperative recordings of neural activity in patients undergoing stereotactic neurosurgery combined with studies in animal models of parkinsonism have led to the accumulation of complementary data regarding these oscillations. In this review we address some of the key issues facing researchers in the field. These issues encompass existing agreements as well as open debates in modern studies of beta band oscillations, including their defining characteristics, links to clinical symptoms and the functional properties of their formation and effects on behavior. We address these questions by comparing and contrasting the results of neurophysiological observations in human patients, MPTP primate model and 6-OHDA rat model with conceptual and computational models of the normal and parkinsonian basal ganglia. Defining a unifying scheme of beta band oscillations and their relation to neurophysiological, functional and clinical phenomena will enable future targeting of these oscillations for both diagnosis and treatment of Parkinson's disease.