Abstract
INTRODUCTION
In Parkinson's disease, the emergence of motor dysfunction is thought to be related to an imbalance between antikinetic and prokinetic patterns of oscillatory activity in the motor network. Invasive recordings from the basal ganglia and cortex in surgical patients have suggested that levodopa and therapeutic deep brain stimulation can suppress antikinetic beta band (13-30 Hz) rhythms while promoting prokinetic gamma band (60-90 Hz) rhythms. Surgical ablation of the globus pallidus internus is one of the oldest effective therapies for Parkinson's disease and gives a remarkable immediate relief from rigidity and bradykinesia, but its effects on oscillatory activity in the motor network have not been studied. We characterize the effects of pallidotomy on cortical oscillatory activity in Parkinson's disease patients.
METHODS
Using a temporary 6-contact lead placed over the sensorimotor cortex in the subdural space, we recorded acute changes in cortical oscillatory activities in 3 Parkinson's disease patients undergoing pallidotomy and compared the results to that of 3 essential tremor patients undergoing thalamotomy.
RESULTS
In all 3 Parkinson's disease patients, we observed the emergence of an approximately 70 to 80 Hz narrow-band oscillation with effective thermolesion of the pallidum. This gamma oscillatory activity was spatially localized over the primary motor cortex, was minimally affected by voluntary movements, and was not found in the motor cortex of essential tremor patients undergoing thalamotomy.
CONCLUSION
Our finding suggests that acute lesioning of the pallidum promotes cortical gamma band oscillations. This may represent an important mechanism for alleviating bradykinesia in Parkinson's disease.
Enhancing Gamma Oscillations Restores Primary Motor Cortex Plasticity in Parkinson's Disease
