title: High and low gamma EEG oscillations in central sensorimotor areas are conversely modulated during the human gait cycle.
abstract: Investigating human brain function is essential to develop models of cortical involvement during walking. Such models could advance the analysis of motor impairments following brain injuries (e.g., stroke) and may lead to novel rehabilitation approaches. In this work, we applied high-density EEG source imaging based on individual anatomy to enable neuroimaging during walking. To minimize the impact of muscular influence on EEG recordings we introduce a novel artifact correction method based on spectral decomposition. High γ oscillations (>60Hz) were previously reported to play an important role in motor control. Here, we investigate high γ amplitudes while focusing on two different aspects of a walking experiment, namely the fact that a person walks and the rhythmicity of walking. We found that high γ amplitudes (60-80Hz), located focally in central sensorimotor areas, were significantly increased during walking compared to standing. Moreover, high γ (70-90Hz) amplitudes in the same areas are modulated in relation to the gait cycle. Since the spectral peaks of high γ amplitude increase and modulation do not match, it is plausible that these two high γ elements represent different frequency-specific network interactions. Interestingly, we found high γ (70-90Hz) amplitudes to be coupled to low γ (24-40Hz) amplitudes, which both are modulated in relation to the gait cycle but conversely to each other. In summary, our work is a further step towards modeling cortical involvement during human upright walking.
authors.affiliation: Graz University of Technology, Institute for Knowledge Discovery, Laboratory of Brain-Computer Interfaces, Graz, Austria; BioTechMed-Graz, Graz, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Seeber
authors.affiliation: Graz University of Technology, Institute for Knowledge Discovery, Laboratory of Brain-Computer Interfaces, Graz, Austria; BioTechMed-Graz, Graz, Austria; Rehabilitation Clinic Judendorf-Strassengel, Judendorf-Strassengel, Austria.
authors.forename: Reinhold
authors.initials: R
authors.lastname: Scherer
authors.affiliation: Graz University of Technology, Institute for Knowledge Discovery, Laboratory of Brain-Computer Interfaces, Graz, Austria; BioTechMed-Graz, Graz, Austria.
authors.forename: Johanna
authors.initials: J
authors.lastname: Wagner
authors.affiliation: Graz University of Technology, Institute for Knowledge Discovery, Laboratory of Brain-Computer Interfaces, Graz, Austria; BioTechMed-Graz, Graz, Austria; Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
authors.forename: Teodoro
authors.initials: T
authors.lastname: Solis-Escalante
authors.affiliation: Graz University of Technology, Institute for Knowledge Discovery, Laboratory of Brain-Computer Interfaces, Graz, Austria; BioTechMed-Graz, Graz, Austria. Electronic address: gernot.mueller@tugraz.at.
authors.forename: Gernot R
authors.initials: GR
authors.lastname: Müller-Putz
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001931:Brain Mapping; D004569:Electroencephalography; D005260:Female; D005684:Gait / Q000502:physiology*; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D009415:Nerve Net / Q000502:physiology; D059906:Neuroimaging; D012371:Robotics; D066191:Sensorimotor Cortex / Q000502:physiology*; D016138:Walking / Q000502:physiology; D055815:Young Adult
keywords: Electroencephalography (EEG) source imaging; High gamma oscillations; Human gait; Robotic gait training; Sensorimotor system