预期姿势调整(APAs)提供躯干的前馈姿势控制,但是它们随着年龄的增长而延迟,影响老年人的平衡和流动性。网状脊髓束有助于躯干的姿势控制;然而,年龄相关的变化在多大程度上影响网状脊髓对躯干APA的贡献在人类中仍然未知。这里,我们测试了一个假设,一个惊人的声音,激活网状脊髓束,改善老年人的延迟APA。22岁(75±6岁)和20名健康的年轻人(21±4岁)进行了自我启动的快速双侧肩屈曲或肩伸展任务,以响应视觉,视觉和听觉(80dB),或视觉和惊人的(115分贝)提示。在肩屈期间记录双侧前三角肌(AD)和竖脊肌(ES)的肌电图(EMG),在肩展期间记录双侧后三角肌(PD)和腹直肌(RA)。在两个年龄组中,所有肌肉的EMG发作在惊人的提示期间缩短,提示原动机(AD或PD)和非原动机(ES或RA)的网状脊髓束的非特异性调节。有趣的是,在令人震惊的提示期间,老年参与者的ESAPA加速到与年轻参与者相似的程度。相反,RA的APA不受老年参与者的惊人提示的影响。我们的结果表明,衰老对网状脊髓束对背部伸肌和腹肌之间APA的功能贡献的不同影响。
Anticipatory postural adjustments (APAs) give feedforward postural control of the trunk, but they are delayed with ageing, affecting balance and mobility in older individuals. The reticulospinal tract contributes to postural control of the trunk; however, the extent to which age-related changes affect the reticulospinal contributions to APAs of the trunk remains unknown in humans. Here, we tested the hypothesis that a startling acoustic sound, which activates the reticulospinal tract, improves delayed APAs in older individuals. Twenty-two old (75 ± 6 years) and 20 healthy young adults (21 ± 4 years) performed a self-initiated fast bilateral shoulder flexion or shoulder extension task in response to visual, visual and auditory (80 dB), or visual and startling (115 dB) cues. Electromyography (EMG) was recorded from bilateral anterior deltoid (AD) and erector spinae (ES) during shoulder flexion and from bilateral posterior deltoid (PD) and rectus abdominis (RA) during shoulder extension. EMG onset of all muscles shortened during the startling cue in both age groups, suggesting a non-specific modulation of the reticulospinal tract on prime movers (AD or PD) and non-prime movers (ES or RA). Interestingly, APAs of the ES were accelerated in older participants to a similar degree as in younger participants during the startling cue. Conversely, APAs of the RA were not influenced by the startling cue in older participants. Our results suggest differential effects of ageing on functional contributions of the reticulospinal tract to APAs between back extensors and abdominal muscles.