TY  - JOUR
A1  - Del Vecchio, Jasmin
A1  - Hanafi, Ibrahem
A1  - Pozzi, Nicoló Gabriele
A1  - Capetian, Philipp
A1  - Isaias, Ioannis U.
A1  - Haufe, Stefan
A1  - Palmisano, Chiara
T1  - Pallidal recordings in chronically implanted dystonic patients: mitigation of tremor-related artifacts
JF  - Bioengineering
N2  - Low-frequency oscillatory patterns of pallidal local field potentials (LFPs) have been proposed as a physiomarker for dystonia and hold the promise for personalized adaptive deep brain stimulation. Head tremor, a low-frequency involuntary rhythmic movement typical of cervical dystonia, may cause movement artifacts in LFP signals, compromising the reliability of low-frequency oscillations as biomarkers for adaptive neurostimulation. We investigated chronic pallidal LFPs with the Percept\(^{TM}\) PC (Medtronic PLC) device in eight subjects with dystonia (five with head tremors). We applied a multiple regression approach to pallidal LFPs in patients with head tremors using kinematic information measured with an inertial measurement unit (IMU) and an electromyographic signal (EMG). With IMU regression, we found tremor contamination in all subjects, whereas EMG regression identified it in only three out of five. IMU regression was also superior to EMG regression in removing tremor-related artifacts and resulted in a significant power reduction, especially in the theta-alpha band. Pallido-muscular coherence was affected by a head tremor and disappeared after IMU regression. Our results show that the Percept PC can record low-frequency oscillations but also reveal spectral contamination due to movement artifacts. IMU regression can identify such artifact contamination and be a suitable tool for its removal.
KW  - dystonia
KW  - tremor
KW  - local field potentials
KW  - globus pallidus
KW  - deep brain stimulation
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-313498
SN  - 2306-5354
VL  - 10
IS  - 4
ER  - 
TY  - JOUR
A1  - Palmisano, Chiara
A1  - Kullmann, Peter
A1  - Hanafi, Ibrahem
A1  - Verrecchia, Marta
A1  - Latoschik, Marc Erich
A1  - Canessa, Andrea
A1  - Fischbach, Martin
A1  - Isaias, Ioannis Ugo
T1  - A fully-immersive virtual reality setup to study gait modulation
JF  - Frontiers in Human Neuroscience
N2  - Objective: Gait adaptation to environmental challenges is fundamental for independent and safe community ambulation. The possibility of precisely studying gait modulation using standardized protocols of gait analysis closely resembling everyday life scenarios is still an unmet need.
Methods: We have developed a fully-immersive virtual reality (VR) environment where subjects have to adjust their walking pattern to avoid collision with a virtual agent (VA) crossing their gait trajectory. We collected kinematic data of 12 healthy young subjects walking in real world (RW) and in the VR environment, both with (VR/A+) and without (VR/A-) the VA perturbation. The VR environment closely resembled the RW scenario of the gait laboratory. To ensure standardization of the obstacle presentation the starting time speed and trajectory of the VA were defined using the kinematics of the participant as detected online during each walking trial. 
Results: We did not observe kinematic differences between walking in RW and VR/A-, suggesting that our VR environment per se might not induce significant changes in the locomotor pattern. When facing the VA all subjects consistently reduced stride length and velocity while increasing stride duration. Trunk inclination and mediolateral trajectory deviation also facilitated avoidance of the obstacle. 
Conclusions: This proof-of-concept study shows that our VR/A+ paradigm effectively induced a timely gait modulation in a standardized immersive and realistic scenario. This protocol could be a powerful research tool to study gait modulation and its derangements in relation to aging and clinical conditions.
KW  - gait modulation
KW  - virtual reality
KW  - obstacle avoidance
KW  - gait analysis
KW  - kinematics
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-267099
SN  - 1662-5161
VL  - 16
ER  -