Localization of beta and high-frequency oscillations within the subthalamic nucleus region

Area of Science:

• Neuroscience
• Neurology
• Biomedical Engineering

Background:

• Parkinsonian bradykinesia and rigidity are linked to excessive beta band oscillations in the subthalamic nucleus.
• High-frequency oscillations (HFO, 150-400 Hz) and their coupling with beta oscillations (beta-HFO PAC) are newly identified spectral peaks potentially involved in Parkinson's pathophysiology.
• The precise neuronal origin of HFO and their clinical utility for deep brain stimulation (DBS) remain unclear, specifically whether they originate from the same neuronal populations as beta oscillations.

Purpose of the Study:

• To investigate the spatial relationship between beta oscillations and HFO within the subthalamic nucleus (STN).
• To determine the origin of HFO relative to beta oscillations and identify the optimal recording site for beta-HFO phase-amplitude coupling (PAC).
• To assess the potential of HFO as a refined target for deep brain stimulation (DBS) in Parkinson's disease.

Main Methods:

• Intraoperative local field potentials (LFPs) were recorded from the STN during DBS electrode placement in 14 patients (26 nuclei).
• Recordings were performed at 4 sites along each electrode trajectory, spaced 2 mm apart, from 4 mm above to 2 mm below the surgical target.
• Analysis identified recording sites with maximal beta power (13-30 Hz), maximal HFO power (150-400 Hz), and maximal beta-HFO PAC.

Main Results:

• The recording sites with maximal beta power and maximal HFO power overlapped in 50% of cases.
• In the remaining 50% of cases, HFO power was more frequently detected at a superior recording site within the STN.
• Beta-HFO PAC was more closely associated with the site of maximal HFO power (45% of cases) than maximal beta power (27% of cases).

Conclusions:

• HFO likely originate from neural populations spatially close to, but slightly superior to, those generating beta oscillations in the STN.
• The distinct spatial distribution of HFO suggests they may represent a separate physiological phenomenon from beta oscillations.
• Further research is needed to determine if targeting these distinct HFO-generating populations can optimize DBS therapy for Parkinson's disease motor symptoms.