Introduction: Pain is a common non-motor symptom of Parkinson’s disease (PD). It remains unclear how pain and sensory information are electrophysiologically encoded in cortical and subcortical structures in humans, and how PD impairs these sensory networks. Deep brain stimulation (DBS) of the subthalamic nucleus (STN), which is used to treat PD motor symptoms, may alleviate pain in patients with PD and modify their pain thresholds at quantitative sensory testing. In this study, we aim to characterize STN local field potentials (LFP) changes associated with pain and thermo-nociception.
Methods: Nociceptive (42 °C, 44 °C, 46 °C, and 48 °C) and non-nociceptive (36 °C, 38 °C, and 40 °C) thermal stimulations were performed bilaterally on the forearm of 10 participants wearing a DBS device recording LFP. We performed the sensory stimulations with DBS turned on or off (in random order). After applying standard filters (Butterworth, Notch) and suppressing cardiac artifacts, we performed Fourier transformations of LFP data to obtain power spectral densities. Wilcoxon signed rank tests or Student's t-test for paired samples were used to compare signal strength in common frequency bands at baseline and in thermal stimulations.
Results: For all experimental conditions, no significant differences were observed between baseline and non-nociceptive thermal stimulation. For nociceptive thermal stimulation, significant differences were observed compared to baseline, both with DBS ON (Delta: P = 0.004) and off (Alpha: P = 0.003; Beta: P < .001; Gamma: P = 0.004). Comparing these two experimental conditions (on/off), significant changes were observed in the Delta (P = 0.003), Beta (P < .001) and Gamma (P = 0.002) bands.
Conclusion : This study reveals significant differences in LFP power spectrum in the STN in response to nociceptive stimulation, with or without DBS. The significant differences observed between on and off DBS suggest a DBS-induced neuromodulation of brain oscillations associated with nociception.
.jpg)
