Beta band modulation by dopamine D2 receptors in the primary motor cortex and pedunculopontine nucleus in a rat model of Parkinson's disease

Beta band (12-30 Hz) hypersynchrony within the basal ganglia-thalamocortical network has been suggested as a hallmark of Parkinson's disease (PD) pathophysiology. Abnormal beta band oscillations are found in the pedunculopontine nucleus (PPN) and primary motor cortex (M1) and are correlated with dopamine depletion. Dopamine acts locomotion and motor performance mainly through dopamine receptors (D1 and D2). However, the precise mechanism by which dopamine receptors regulate beta band electrophysiological activities between the PPN and M1 is still unknown. Here, we recorded the neuronal activity of the PPN and M1 simultaneously by the administration of the drug (SCH23390 and raclopride), selectively blocking the dopamine D1 receptor and D2 receptor. We discovered that the increased coherent activity of the beta band (12-30 Hz) between M1 and PPN in the lesioned group could be reduced and restored by injecting raclopride in the resting and wheel running states. Our studies revealed the unique role of D2 dopamine receptor signaling in regulating beta band oscillatory activity in M1 and PPN and their relationship after the loss of dopamine, which contributes to elucidating the underlying mechanism of the pathophysiology of PD.