Walker Simon, Monto Simo, Piirainen Jarmo M, Avela Janne, Tarkka Ina M, Parviainen Tiina M, Piitulainen Harri
NeuroMuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
Department of Psychology, Centre for Interdisciplinary Brain Research, University of Jyväskylä, Jyväskylä, Finland.
Front Aging Neurosci. 2020 May 19;12:117. doi: 10.3389/fnagi.2020.00117. eCollection 2020.
Healthy aging is associated with deterioration of the sensorimotor system, which impairs balance and somatosensation. However, the exact age-related changes in the cortical processing of sensorimotor integration are unclear. This study investigated primary sensorimotor cortex (SM1) oscillations in the 15-30 Hz beta band at rest and following (involuntary) rapid stretches to the triceps surae muscles (i.e., proprioceptive stimulation) of young and older adults. A custom-built, magnetoencephalography (MEG)-compatible device was used to deliver rapid (190°·s) ankle rotations as subjects sat passively in a magnetically-shielded room while MEG recorded their cortical signals. Eleven young (age 25 ± 3 years) and 12 older (age 70 ± 3 years) adults matched for physical activity level demonstrated clear 15-30 Hz beta band suppression and rebound in response to the stretches. A sub-sample (10 young and nine older) were tested for dynamic balance control on a sliding platform. Older adults had greater cortical beta power pre-stretch (e.g., right leg: 4.0 ± 1.6 fT vs. 5.6 ± 1.7 fT, = 0.044) and, subsequently, greater normalized movement-related cortical beta suppression post-proprioceptive stimulation (e.g., right leg: -5.8 ± 1.3 vs. -7.6 ± 1.7, = 0.01) than young adults. Furthermore, poorer balance was associated with stronger cortical beta suppression following proprioceptive stimulation ( = -0.478, = 0.038, = 19). These results provide further support that cortical processing of proprioception is hindered in older adults, potentially (adversely) influencing sensorimotor integration. This was demonstrated by the impairment of prompt motor action control, i.e., regaining perturbed balance. Finally, SM1 cortex beta suppression to a proprioceptive stimulus seems to indicate poorer sensorimotor functioning in older adults.
健康衰老与感觉运动系统的衰退有关，这会损害平衡和躯体感觉。然而，感觉运动整合的皮质处理中与年龄相关的确切变化尚不清楚。本研究调查了年轻人和老年人在静息状态下以及在（非自愿地）对腓肠肌进行快速拉伸（即本体感受刺激）后，初级感觉运动皮层（SM1）在15 - 30Hzβ波段的振荡情况。当受试者被动坐在磁屏蔽室中时，使用定制的、与脑磁图（MEG）兼容的设备进行快速（190°·s）的踝关节旋转，同时MEG记录他们的皮质信号。11名身体活动水平匹配的年轻人（年龄25±3岁）和12名老年人（年龄70±3岁）在接受拉伸时表现出明显的15 - 30Hzβ波段抑制和反弹。对一个子样本（10名年轻人和9名老年人）在滑动平台上进行动态平衡控制测试。老年人在拉伸前具有更高的皮质β功率（例如，右腿：4.0±1.6 fT对5.6±1.7 fT，P = 0.044），随后，在本体感受刺激后，与年轻人相比，具有更大的与运动相关的归一化皮质β抑制（例如，右腿：-5.8±1.3对-7.6±1.7，P = 0.01）。此外，平衡能力较差与本体感受刺激后更强的皮质β抑制相关（r = -0.478，P = 0.038，n = 19）。这些结果进一步支持了老年人本体感觉的皮质处理受到阻碍，这可能（不利地）影响感觉运动整合。这通过即时运动动作控制的受损得到证明，即恢复被干扰的平衡。最后，SM1皮层对本体感受刺激的β抑制似乎表明老年人的感觉运动功能较差。
