High and low gamma EEG oscillations in central sensorimotor areas are conversely modulated during the human gait cycle

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 gamma oscillations (>60 Hz) were previously reported to play an important role in motor control. Here, we investigate high gamma 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 gamma amplitudes (60-80 Hz), located focally in central sensorimotor areas, were significantly increased during walking compared to standing. Moreover, high gamma (70-90 Hz) amplitudes in the same areas are modulated in relation to the gait cycle. Since the spectral peaks of high gamma amplitude increase and modulation do not match, it is plausible that these two high gamma elements represent different frequency-specific network interactions. Interestingly, we found high gamma (70-90 Hz) amplitudes to be coupled to low gamma (24-40 Hz) 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. (C) 2015 Elsevier Inc. All rights reserved.