Search

Background: STN-DBS effectively treats motor symptoms of advanced PD. Nonmotor cognitive symptoms, such as impaired impulse control or decision making, may either improve or worsen with DBS. A potential mediating factor of DBS-induced modulation of cognition is the electrode position within the STN with regard to functional subareas of parallel motor, cognitive, and affective basal ganglia loops. However, to date, the volume of tissue activated and weighted stimulation of STN motor versus nonmotor territories are yet to be linked to differential DBS effects on cognition.Objectives: We aim to investigate whether STN-DBS influences risk-reward trade-off decisions and analyze its dependency on electrode placement.Methods: Seventeen PD patients ON and OFF STN-DBS and 17 age-matched healthy controls conducted a sequential decision-making task with escalating risk and reward. We computed the effect of STN-DBS on risk-reward trade-off decisions, localized patients' bilateral electrodes, and analyzed the predictive value of volume of tissue activated in STN motor and nonmotor territories on behavioral change.Results: We found that STN-DBS not only improves PD motor symptoms, but also normalizes overly risk-averse decision behavior in PD. Intersubject variance in electrode location could explain this behavioral change. Specifically, if STN-DBS activated preferentially STN motor territory, patients' risk-reward trade-off decisions more resembled those of healthy controls.Conclusions: Our findings support the notion of convergence of different functional circuits within the STN and imply a positive effect of well-placed STN-DBS on nonmotor cognitive functioning in PD. © 2018 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Background: Exaggerated beta power has been discussed as a disease-specific biomarker for Parkinson's disease (PD) and has recently been suggested to rely on prolonged bursts of subthalamic beta synchronization.Objective: In this study, we test whether prolonged bursts are disease specific for beta activity in PD by comparison to oscillatory activity in dystonia.Methods: Pallidal local field potentials were recorded from 5 PD patients ON and OFF dopaminergic medication and 5 dystonia patients. Synchronization of beta and low-frequency oscillations in bursts was compared between groups with respect to their duration, amplitude, and rate.Results: Pallidal beta bursts were longer in PD-OFF than PD-ON or dystonia (P < .05). PD-ON and dystonia displayed similar beta burst dynamics. Low-frequency burst features showed no differences across groups.Conclusions: Prolonged burst duration appears as a disease-specific feature for beta activity in PD across the basal ganglia. With dopaminergic medication, beta bursts in PD resemble those in dystonia, which supports the notion of short beta bursts as a physiological pattern. © 2018 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

The subthalamic nucleus is part of a global stopping network that also includes the presupplementary motor area and inferior frontal gyrus of the right hemisphere. In Parkinson's disease, subthalamic deep brain stimulation improves movement initiation and velocity, but its effect on stopping of ongoing movement is unknown. Here, we examine the relation between movement stopping and connectivity of stimulation volumes to the stopping network. Stop and go times were collected in 17 patients with Parkinson's disease on and off subthalamic stimulation during visually cued initiation and termination of continuous, rotational movements. Deep brain stimulation contacts were localized; the stimulation volume computed and connectivity profiles estimated using an openly available, normative structural connectome. Subthalamic stimulation significantly increased stop times, which correlated with the connectivity of the stimulation volume to presupplementary motor area and inferior frontal gyrus of the right hemisphere. The robustness of this finding was validated using three separate analysis streams: voxel-wise whole-brain connectivity, region of interest connectivity and a tract-centred method. Our study sheds light on the role of the fronto-subthalamic inhibitory triangle in stopping of ongoing movements and may inspire circuit based adaptive stimulation strategies for control of stopping impairment, possibly reflected in stimulation-induced dyskinesia. [ABSTRACT FROM AUTHOR]

Objective: Beta band oscillations in the subthalamic nucleus (STN) have been proposed as a pathophysiological signature in patients with Parkinson's disease (PD). The aim of this study was to investigate the potential association between oscillatory activity in the STN and symptom severity in PD.Methods: Subthalamic local field potentials were recorded from 63 PD patients in a dopaminergic OFF state. Power-spectra were analyzed for the frequency range from 5 to 95 Hz and correlated with individual UPDRS-III motor scores in the OFF state.Results: A correlation between total UPDRS-III scores and 8 to 35 Hz activity was revealed across all patients (ρ = 0.44, P < .0001). When correlating each frequency bin, a narrow range from 10 to 15 Hz remained significant for the correlation (false discovery rate corrected P < .05).Conclusion: Our results show a correlation between local STN 8 to 35 Hz power and impairment in PD, further supporting the role of subthalamic oscillatory activity as a potential biomarker for PD. [ABSTRACT FROM AUTHOR]

Movement is accompanied by changes in the degree to which neurons in corticobasal ganglia loops synchronize their activity within discrete frequency ranges. Although two principal frequencybands--beta (15-30 Hz) andgamma(60 -90Hz)--have been implicated in motor control, the precise functional correlates of their activities remain unclear. Local field potential (LFP) recordings in humans with Parkinson's disease undergoing surgery for deep brain stimulation to the subthalamic nucleus (STN) indicate that spectral changes both anticipate movement and occur perimovement. The extent to which such changes are modulated by cognitive factors involved in making a correct response seems critical in characterizing the functional associations of these oscillations. Accordingly, by recording LFP activity from the STN in parkinsonian patients, we demonstrate that perimovement beta and gamma reactivity is modulated by task complexity in a dopamine-dependent manner, despite the dynamics of the movement remaining unchanged. In contrast, spectral changes occurring in anticipation of future movement were limited to the beta band and, although modulated by dopaminergic therapy, were not modulated by task complexity. Our findings suggest two dopamine-dependent processes indexed by spectral changes in the STN: (1) an anticipatory activity reflected in the beta band that signals the likelihood of future action but does not proactively change with the cognitive demands of the potential response, and (2) perimovement activity that involves reciprocal beta and gamma band changes and is not exclusively related to explicit motor processing. Rather perimovement activity can also vary with, and may reflect, the cognitive complexity of the task. [ABSTRACT FROM AUTHOR]