Age-Related Differences in Stepping Reactions to a Balance Perturbation: A Functional Near-Infrared Spectroscopy and Surface Electromyography Study

Abstract

We sought to investigate age-related differences in stepping reactions to a sudden balance perturbation, focusing on muscle activity and cortical activation. A total of 18 older healthy adults (older group, OG) and 16 young healthy adults (young group, YG) were recruited into this study. A cable-pull instrument was used to induce a forward perturbation at the waist level among participants, who were required to take the right step to maintain their postural balance. The seven right lower-limb muscle activities during periods of compensatory postural adjustments (CPAs) were recorded by surface electromyography. At the same time, the signals of channels located in the prefrontal, temporal and parietal lobes were recorded by functional near-infrared spectroscopy (fNIRS) during the whole process. Integral electromyograms of the right peroneus muscle, gluteus medius, and lateral gastrocnemius muscles showed greater activity for the OG in the CPA periods. Two channels belonging to the right pre-frontal (PFC) and pre-motor cortex (PMC) revealed lower activation in the OG compared with the YG. These findings can help us to better understand the differences at the peripheral and central levels and may provide some suggestions for future neuromodulation techniques and other clinical treatments.

Stroke-Related Alterations in the Brain’s Functional Connectivity Response Associated with Upper Limb Multi-Joint Linkage Movement

“…Electroencephalograms (EEG) have strong temporal resolution and have the advantages of being simple and rapid, but the spatial resolution of EEG is low [5][6][7]. Functional near infrared spectroscopy (fNIRS), a noninvasive optical imaging technique, can be applied at the tissue surface through an optical probe [8,9]. Changes in the concentrations of oxyhemoglobin (delta HbO 2 ) and deoxyhemoglobin (delta HbR) can be measured by emitting and receiving near-infrared light (650-1000 nm) to reflect the hemodynamic changes in the cerebral tissues [10][11][12][13][14], providing a noninvasive, real-time, dynamic and repeatable method of detecting brain function for stroke patients.…”