Objective: This study aims to systematically investigate the spatial segregation of a wide range of spectral features of local field potentials (LFPs) within the STN in patients with Parkinson’s disease (PD).

Background: Evidence is accruing that features of different frequency ranges can be linked to heterogenous symptom and behavioral manifestations in patients with movement disorders. Moreover, the functional and somatotopic organization of the subthalamic nucleus (STN) can be represented in preferred regional distributions of spectral features (e.g. beta hotspot in the motor STN). It can be assumed that a more refined spatial segregation of spectral features within the STN could be one further key to individualize DBS.

Method: STN-LFPs were recorded intra-operatively with common referencing from 65 PD patients (119 hemispheres) using multi-contact segmented DBS electrodes with the patients awake and at rest. We extracted the power spectral density (PSD) for different frequency bands: Delta- (1-3.5 Hz), Theta- (4-7 Hz), Alpha- (8-12 Hz), low-Beta- (13-20 Hz) and high-Beta- (21-30 Hz) low-Gamma (31-45Hz), high-Gamma-(60-90Hz), fast-gamma-(110-140Hz) and high-frequency oscillations (HFO, 252-348 Hz). The spectral distribution of the oscillatory components within the normalized anatomical STN were assessed and their spatial hot spots and focality determined.

Results: The spectral features in STN-LFP show heterogenous spatial topographical hotspots of their power spectral density most pronounced in the superior-inferior axis. The spatial hotspot of features from the lower frequency range (Delta, Theta, Alpha, low/high-Beta and low-Gamma) tend to be localized more superior, while features from the higher frequency range, in particular HFO show their spatial density peaks more inferior relative to a random distribution. Moreover, averaged across all axes and features, HFO showed the spatially most circumscribed oscillatory hot spot.

Conclusion: This study reveals a heterogeneous distribution and focality of a broad range of LFP spectral features in the STN of large cohort of PD patents recorded from segmented multi-contact DBS leads. The spatial and functional segregation of spectral features could inform surgical targeting, DBS programming and may enable a more differentiated feedback signal selection for adaptive DBS.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/spectral-somatotopy-of-the-human-subthalamic-nucleus-in-parkinsons-disease/