Higher neuronal discharge rate in the motor area of the subthalamic nucleus of Parkinsonian patients

Abstract

In Parkinson's disease, pathological synchronous oscillations divide the subthalamic nucleus (STN) of patients into a dorsolateral oscillatory region and ventromedial nonoscillatory region. This bipartite division reflects the motor vs. the nonmotor (associative/limbic) subthalamic areas, respectively. However, significant topographic differences in the neuronal discharge rate between these two STN subregions in Parkinsonian patients is still controversial. In this study, 119 STN microelectrode trajectories (STN length > 2 mm, mean = 5.32 mm) with discernible oscillatory and nonoscillatory regions were carried on 60 patients undergoing deep brain stimulation surgery for Parkinson's disease. 2,137 and 2,152 multiunit stable signals were recorded (recording duration > 10 s, mean = 21.25 s) within the oscillatory and nonoscillatory STN regions, respectively. Spike detection and sorting were applied offline on every multiunit stable signal using an automatic method with systematic quantification of the isolation quality (range = 0-1) of the identified units. In all, 3,094 and 3,130 units were identified in the oscillatory and nonoscillatory regions, respectively. On average, the discharge rate of better-isolated neurons (isolation score > 0.70) was higher in the oscillatory region than the nonoscillatory region (44.55 ± 0.87 vs. 39.97 ± 0.77 spikes/s, N = 665 and 761, respectively). The discharge rate of the STN neurons was positively correlated to the strength of their own and their surrounding 13- to 30-Hz beta oscillatory activity. Therefore, in the Parkinsonian STN, beta oscillations and higher neuronal discharge rate are correlated and coexist in the motor area of the STN compared with its associative/limbic area.

Evaluation of Spike Sorting Algorithms: Application to Human Subthalamic Nucleus Recordings and Simulations

“…There are deviations in the number of detected SUs, in the percentage of US and rpv, as well as differences in the cluster quality measures. While the IS is typically used to select well isolated SUs [38,28,9] we here apply it to verify an augmented occurrence of well isolated SUs if the corresponding waveforms are distinct and thus easy to separate.…”

Phase-dependent modulation as a novel approach for therapeutic brain stimulation

“…The recording of local field potentials (LFP) revealed that the most upper electrode contact of the quadripolar lead has the highest spectral power in the beta-frequency band (15–30 Hz, Figure 2A), indicating that it is located in the sensorimotor part of the STN (Figure 2A) (Holdefer et al, 2010; Yoshida et al, 2010; Zaidel et al, 2010; Novak et al, 2011; Deffains et al, 2014). Using this electrode contact as a reference, the neighboring contact revealed the most prominent phase synchronization when applying the Weighted Phase Lag Index (WPLI).…”

Anesthesia reduces discharge rates in the human pallidum without changing the discharge rate ratio between pallidal segments

“…Recording stability was assessed (Deffains et al, 2014) and only stable recording segments longer than 10 s were used for further analyses. An automatic spike detection and sorting method was then used to isolate single units (Deffains et al, 2014) from the stable recording segments. An isolation score was calculated for each unit that was identified by the spike sorter software (Joshua et al, 2007).…”

“…Today, more than 25 years later, it is still the most widely accepted model linking dopamine imbalance in the striatum, rate of discharge in the nuclei of the basal ganglia and the motor expression of hypo-and hyper-kinetic movement disorders. Deep brain stimulation (DBS), a recognized treatment for both Dystonia and Parkinson's disease, allows researchers to test some of the predictions of this model in humans (Starr et al, 2005;Tang et al, 2007;Deffains et al, 2014).…”