Assessing Neurokinematic and Neuromuscular Connectivity During Walking Using Mobile Brain-Body Imaging

Abstract

Gait is a common but rather complex activity that supports mobility in daily life. It requires indeed sophisticated coordination of lower and upper limbs, controlled by the nervous system. The relationship between limb kinematics and muscular activity with neural activity, referred to as neurokinematic and neuromuscular connectivity (NKC/NMC) respectively, still needs to be elucidated. Recently developed analysis techniques for mobile high-density electroencephalography (hdEEG) recordings have enabled investigations of gait-related neural modulations at the brain level. To shed light on gait-related neurokinematic and neuromuscular connectivity patterns in the brain, we performed a mobile brain/body imaging (MoBI) study in young healthy participants. In each participant, we collected hdEEG signals and limb velocity/electromyography signals during treadmill walking. We reconstructed neural signals in the alpha (8–13 Hz), beta (13–30 Hz), and gamma (30–50 Hz) frequency bands, and assessed the co-modulations of their power envelopes with myogenic/velocity envelopes. Our results showed that the myogenic signals have larger discriminative power in evaluating gait-related brain-body connectivity with respect to kinematic signals. A detailed analysis of neuromuscular connectivity patterns in the brain revealed robust responses in the alpha and beta bands over the lower limb representation in the primary sensorimotor cortex. There responses were largely contralateral with respect to the body sensor used for the analysis. By using a voxel-wise analysis of variance on the NMC images, we revealed clear modulations across body sensors; the variability across frequency bands was relatively lower, and below significance. Overall, our study demonstrates that a MoBI platform based on hdEEG can be used for the investigation of gait-related brain-body connectivity. Future studies might involve more complex walking conditions to gain a better understanding of fundamental neural processes associated with gait control, or might be conducted in individuals with neuromotor disorders to identify neural markers of abnormal gait.

Electrophysiological approaches to understanding brain-muscle interactions during gait: a systematic review

“…We analyzed the set-up and processing techniques for the EEG signal acquisition (Figure 5). Two studies used a limited number of two electrodes, and Zhao et al opted for a set of 128 electrodes (Zhao et al, 2022). Two different methods for EEG artifact removal were primarily used.…”

“…Five studies conducted EEG data analysis in the source space, which involves mapping the recorded electrical signals to specific brain regions responsible for generating them. In the study of Zhao et al an individual MRI of the participant was used to enhance the precision of source localization (Zhao et al, 2022).…”

“…Only four studies used the signal in the source space. Using source localization, Zhao et al showed NMC not only between the muscle and the primary motor cortex, but also between the muscle and the premotor cortex, posterior parietal cortex, and cerebellum (Zhao et al, 2022). This approach holds promise for providing a more comprehensive understanding of the complex sensorimotor system by precisely identifying the EEG signal sources.…”

“…recorded electrical signals to specific brain regions responsible for generating them. In the study ofZhao et al an individual MRI of the participant was used to enhance the precision of source localization(Zhao et al, 2022).Various approaches have been employed for the selection of electrodes of interest in the reviewed studies. Most of these studies utilized the central Cz electrode as a reference point to calculate NMC.…”

Brain Networks Modulation during Simple and Complex Gait: A “Mobile Brain/Body Imaging” Study

“…For this protocol, we customized a MoBI platform, like [19], to collect hdEEG data while recording gait spatiotemporal parameters during overground walking.…”