Distinctive neuronal firing patterns in subterritories of the subthalamic nucleus

•We studied the neuronal activity of STN subterritories as anatomically defined on fused CT/MRI images.•We showed that STN subterritories exhibit a distinctive burst firing rate.•The different bursting activity might reflect the functional organisation of the STN.

ObjectiveDeep brain stimulation of the subthalamic nucleus (STN-DBS) is an established treatment for Parkinson's disease (PD). Anatomical connectivity analyses and task-related physiological studies have divided the STN into different functional domains: sensorimotor, limbic, and associative - located in its dorsolateral (dSTN), anteroventral (vSTN) and medial territories, respectively. Targeting sensorimotor STN is essential for stimulation efficacy and is supported by intraoperative micro-electrode recordings. A different neuronal signature in microelectrode recordings across STN subterritories was explored in this study.MethodsStable recordings from 30 PD patients were assigned to dSTN or vSTN by means of an anatomical method (based on fused computed tomography/magnetic resonance images) and through a priori tri-segmented partition of the recording itself. We computed the inter-spike interval (ISI) and ISI-characteristics, mean firing rate (MFR), discharge patterns and mean burst rate (MBR) of each detected single unit activity.ResultsWe showed a different MBR between dSTN and vSTN (1.51 ± 0.18 vs. 1.76 ± 0.22 events/minute, Wilcoxon rank sum test, p < 0.05) and a trend in the difference between their MFR (12.78 vs. 15.05 Hz, Wilcoxon rank sum test, p = 0.053) only with the anatomically based method.ConclusionBurst firing differs across STN subterritories.SignificanceDifferent functions of subthalamic domains might be reflected by distinctive burst signalling of its subterritories.