Abnormal rhythmic brain activity in the beta frequency band (13–35 Hz) is assumed to have a role in Parkinson’s disease (PD); nevertheless, growing data suggests that changes in high-frequency ranges (>100 Hz) are also pathophysiologically relevant. Power in high-frequency oscillations in the subthalamic nucleus (STN) is enhanced with dopaminergic medication and during voluntary movements, suggesting that these brain rhythms are involved in normal basal ganglia function. For a review, researchers wanted to determine if comparable communication happens in the internal globus pallidus (GPi), a nucleus that is increasingly being used as a target for deep brain stimulation (DBS) for Parkinson’s disease (PD). Spontaneous and movement-related GPi field potentials were recorded from DBS leads in 5 externalized patients with PD on and off dopaminergic treatment, as well as in 3 rhesus monkeys before and after the neurotoxin 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine induction of parkinsonism.

Researchers discovered a strong oscillatory peak centered at 200–300 Hz in the parkinsonian state, which increased with movement. The degree of high-frequency oscillation modulation was shown to be adversely linked with bradykinesia in patients. High-frequency oscillations were generally absent in monkeys under naive conditions but appeared following exposure to the neurotoxic 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine. On treatment, spontaneous high-frequency oscillations were dramatically reduced in patients.

The findings support the theory that excessive, movement-modulated high-frequency oscillations in the GPi are pathophysiological hallmarks of PD. These findings imply that the functional role(s) of high-frequency oscillations may differ between the STN and the GPi, and they warrant further exploration into their link to motor control in normal and pathological situations.

 

Reference:movementdisorders.onlinelibrary.wiley.com/doi/10.1002/mds.28566