Biology subjects

Waldthaler, J.

Publications and source records attributed to Waldthaler, J..

3 recordsLinked to original sources

bioRxiv2022

High-and Low-Frequency Deep Brain Stimulation in the Subthalamic Nucleus differentially modulate Response Inhibition and Action Selection in Parkinson's Disease

BackgroundWhile deep brain stimulation (DBS) in the subthalamic nucleus (STN) improves motor functions in Parkinsons disease (PD), it has also been associated with increased impulsivity. MethodsA combined approach of eye-tracking and high-density EEG was used to investigate how high- and low-frequency DBS impact impulsive actions in the antisaccade task in a cohort of ten persons with PD. Computational modelling of the behavioral outcomes allowed a nuanced insight into the effect of DBS on response inhibition and action selection processes. Results: Against our expectations, both 130 Hz- and 60 Hz-DBS improved response inhibition as both resulted in a reduced rate of early reflexive errors. Correspondingly, DBS with both frequencies led to increased desynchronization of beta power during the preparatory period which may be a correlate of anticipatory activation in the oculomotor network. Low-frequency DBS additionally was associated with increased midfrontal theta power, an established marker of cognitive control. While higher midfrontal theta power predicted longer antisaccade latencies in off-DBS state on a trial-by-trial basis, 130 Hz-DBS reversed this relationship. As informed by the computational model, 130 Hz-DBS further led to a shift in the speed-accuracy trade-off causing an acceleration and error-proneness of actions later in the trial. ConclusionsOur results disentangle the impact of DBS on early and late impulsive actions. Only 130 Hz-DBS may disrupt theta-mediated cognitive control mechanisms via medial frontal - STN pathways that are involved in delaying action selection. 60 Hz-DBS may provide beneficial effects on response inhibition without the detrimental effect on action selection seen with 130 Hz-DBS. FundingThis study was supported by the SUCCESS program of Philipps-University Marburg (JW), the Hessian Ministry of Sciences and the Arts, clusterproject: The Adaptive Mind - TAM (FB / AK) and the German Research Foundation (DFG). International Research Training Group 1901 (FB / AK)

neuroscience↗

bioRxiv2021

Visual perturbation of balance suggests impaired neuromuscular stability but intact visuo-motor control in Parkinson's disease

Postural instability marks one of the most disabling features of Parkinsons disease (PD), but only reveals itself after affected brain areas have already been significantly damaged. Thus, there is a need to detect deviations in balance and postural control before visible symptoms occur. In this study, we visually perturbed balance in the anterior-posterior direction using sinusoidal oscillations of a moving room in virtual reality at different frequencies. We tested three groups: individuals with PD under dopaminergic medication, an age-matched control group, and a group of young healthy adults. We tracked their centre of pressure and their full-body motion. We investigated sway amplitudes and applied newly introduced phase-locking analyses to investigate responses across participants bodies. Patients exhibited significantly higher sway amplitudes as compared to the control subjects. However, their sway was phase-locked to the visual motion like that of age-matched and young healthy adults. Furthermore, all groups successfully compensated for the visual perturbation by - most likely reflexively - phase-locking their sway to the stimulus. As frequency of the perturbation increased, distribution of phase-locking (PL) across the body revealed a shift of the highest PL-values from the upper body towards the hip-region for young healthy adults, which could not be observed in patients and elderly healthy adults. Our findings suggest an impaired neuromuscular stability, but intact visuomotor processing in early stages of PD, while less flexibility to adapt postural strategy to different perturbations revealed to be an effect of age rather than disease. New & NoteworthyA better understanding of visuomotor control in Parkinsons disease (PD) potentially serves as a tool for earlier diagnosis, which is crucial for improving patients quality of life. In our study, we assess body sway responses to visual perturbations of the balance control system in patients with early-to-mid stage PD, using motion tracking along with recently established phase-locking techniques. Our findings suggest patients at this stage to have an impaired muscular stability but intact visuomotor control.

neuroscience↗

bioRxiv2019

Reduction of spontaneous cortical beta bursts in Parkinson’s disease is linked to symptom severity

Parkinsons disease is characterized by a gradual loss of dopaminergic neurons, which are associated with altered neuronal activity in the beta band (13-30 Hz). Assessing beta band activity typically involves transforming the time-series to get the power of the signal in the frequency-domain. Such transformation assumes that the time-series can be reduced to a combination of steady-state sine-and cosine waves. However, recent studies have suggested that this approach masks relevant biophysical features in the beta band activity--for example, that the beta band exhibits transient bursts of high-amplitude activity.\n\nIn an exploratory study we used magnetoencephalography (MEG) to record cortical beta band activity to characterize how spontaneous cortical beta bursts manifest in Parkinsons patients ON and OFF dopaminergic medication, and compare this to matched healthy controls. From three minutes of MEG data, we extracted the time-course of beta band activity from the sensorimotor cortex and characterized high-amplitude epochs in the signal to test if they exhibited burst like properties. We then compared the rate, duration, inter-burst interval, and peak amplitude of the high-amplitude epochs between the Parkinsons patients and healthy controls.\n\nOur results show that Parkinsons patients OFF medication had a 6-17% lower beta bursts rate compared to healthy controls, while both the duration and the amplitude of the bursts were the same for Parkinsons patients and healthy controls and medicated state of the Parkinsons patients. These data thus support the view that beta bursts are fundamental underlying features of beta band activity, and show that changes in cortical beta band power in PD can be explained primarily by changes in the underlying burst rate. Importantly, our results also revealed a relationship between beta bursts rate and motor symptom severity in PD: a lower burst rate scaled with increased in severity of bradykinesia and postural/kinetic tremor. Beta burst rate might thus serve as neuromarker for Parkinsons disease that can help in the assessment of symptom severity in Parkinsons disease or evaluate treatment effectiveness.

neuroscience↗