Palmer Jacqueline A, Payne Aiden M, Ting Lena H, Borich Michael R
Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University, Atlanta, GA, United States.
Department of Biomedical Engineering, Emory and Georgia Tech, Atlanta, GA, United States.
Front Aging Neurosci. 2021 Jul 14;13:684743. doi: 10.3389/fnagi.2021.684743. eCollection 2021.
Heightened reliance on the cerebral cortex for postural stability with aging is well-known, yet the cortical mechanisms for balance control, particularly in relation to balance function, remain unclear. Here we aimed to investigate motor cortical activity in relation to the level of balance challenge presented during reactive balance recovery and identify circuit-specific interactions between motor cortex and prefrontal or somatosensory regions in relation to metrics of balance function that predict fall risk. Using electroencephalography, we assessed motor cortical beta power, and beta coherence during balance reactions to perturbations in older adults. We found that individuals with greater motor cortical beta power evoked following standing balance perturbations demonstrated lower general clinical balance function. Individual older adults demonstrated a wide range of cortical responses during balance reactions at the same perturbation magnitude, showing no group-level change in prefrontal- or somatosensory-motor coherence in response to perturbations. However, older adults with the highest prefrontal-motor coherence during the post-perturbation, but not pre-perturbation, period showed greater cognitive dual-task interference (DTI) and elicited stepping reactions at lower perturbation magnitudes. Our results support motor cortical beta activity as a potential biomarker for individual level of balance challenge and implicate prefrontal-motor cortical networks in distinct aspects of balance control involving response inhibition of reactive stepping in older adults. Cortical network activity during balance may provide a neural target for precision-medicine efforts aimed at fall prevention with aging.
随着年龄增长，对大脑皮层维持姿势稳定性的依赖增加是众所周知的，但平衡控制的皮层机制，尤其是与平衡功能相关的机制，仍不清楚。在这里，我们旨在研究与反应性平衡恢复过程中呈现的平衡挑战水平相关的运动皮层活动，并确定运动皮层与前额叶或体感区域之间特定回路的相互作用，这些相互作用与预测跌倒风险的平衡功能指标有关。我们使用脑电图评估了老年人在平衡反应过程中对扰动的运动皮层β功率和β相干性。我们发现，在站立平衡扰动后诱发运动皮层β功率更高的个体，其一般临床平衡功能较低。在相同扰动幅度下，个体老年人在平衡反应过程中表现出广泛的皮层反应，在对扰动的反应中，前额叶或体感-运动相干性没有群体水平的变化。然而，在扰动后（而非扰动前）阶段前额叶-运动相干性最高的老年人表现出更大的认知双任务干扰（DTI），并在较低的扰动幅度下引发跨步反应。我们的结果支持运动皮层β活动作为个体平衡挑战水平的潜在生物标志物，并表明前额叶-运动皮层网络在平衡控制的不同方面发挥作用，包括抑制老年人反应性跨步。平衡过程中的皮层网络活动可能为旨在预防老年人跌倒的精准医学努力提供一个神经靶点。
