Neuronal oscillations of the pedunculopontine nucleus in progressive supranuclear palsy: Influence of levodopa and movement.

Objective: The pedunculopontine nucleus (PPN) has been proposed as a new deep brain stimulation (DBS) target for the treatment in idiopathic Parkinson's syndrome (IPS) and progressive supranuclear palsy (PSP). In IPS, levodopa has been shown to induce alpha activity in the PPN, indicating a possible physiological role for these oscillations in movement control. Despite shared clinical features, the PPN is more severely affected in PSP than IPS. Here we investigated neuronal oscillations in the PPN in PSP and the influence of levodopa and movement.

Methods: Local field potentials were recorded bilaterally from the PPN of 4 PSP patients at rest, with levodopa and during self-paced leg movements.

Results: During rest, levodopa administration was associated with significantly increased alpha and reduced gamma activity in the PPN. Without levodopa, continuous movements were associated with reduced alpha and beta power. These differences between oscillatory power during movement and resting state were not observed with levodopa administration.

Conclusion: In PSP the changes in neuronal oscillations in the PPN region on levodopa administration are similar to those reported in IPS. The enhancement of lower frequency oscillations in the PPN is possibly influenced by a dopaminergic activation of the striatal pathway and a reduced pallidal inhibition.

Significance: Levodopa influences neuronal oscillations at low and high frequencies in the PPN region in Parkinsonian disorders.