Happee Riender, de Bruijn Edo, Forbes Patrick A, van der Helm Frans C T
Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
J Biomech. 2017 Jun 14;58:203-211. doi: 10.1016/j.jbiomech.2017.05.005. Epub 2017 May 17.
The human head-neck system requires continuous stabilization in the presence of gravity and trunk motion. We investigated contributions of the vestibulocollic reflex (VCR), the cervicocollic reflex (CCR), and neck muscle co-contraction to head-in-space and head-on-trunk stabilization, and investigated modulation of the stabilization strategy with the frequency content of trunk perturbations and the presence of visual feedback. We developed a multisegment cervical spine model where reflex gains (VCR and CCR) and neck muscle co-contraction were estimated by fitting the model to the response of young healthy subjects, seated and exposed to anterior-posterior trunk motion, with frequency content from 0.3 up to 1, 2, 4 and 8Hz, with and without visual feedback. The VCR contributed to head-in-space stabilization with a strong reduction of head rotation (<8Hz) and a moderate reduction of head translation (>1Hz). The CCR contributed to head-on-trunk stabilization with a reduction of head rotation and head translation relative to the trunk (<2Hz). The CCR also proved essential to stabilize the individual intervertebral joints and prevent neck buckling. Co-contraction was estimated to be of minor relevance. Control strategies employed during low bandwidth perturbations most effectively reduced head rotation and head relative displacement up to 3Hz while control strategies employed during high bandwidth perturbations reduced head global translation between 1 and 4Hz. This indicates a shift from minimizing head-on-trunk rotation and translation during low bandwidth perturbations to minimizing head-in-space translation during high bandwidth perturbations. Presence of visual feedback had limited effects suggesting increased usage of vestibular feedback.
在重力和躯干运动存在的情况下，人体头颈部系统需要持续稳定。我们研究了前庭颈反射（VCR）、颈颈反射（CCR）和颈部肌肉共同收缩对头在空间和头在躯干上稳定的贡献，并研究了随着躯干扰动的频率成分和视觉反馈的存在对稳定策略的调节。我们开发了一个多节段颈椎模型，通过将该模型与年轻健康受试者的反应进行拟合来估计反射增益（VCR和CCR）和颈部肌肉共同收缩，这些受试者坐着并暴露于前后躯干运动中，频率范围从0.3到1、2、4和8Hz，有或没有视觉反馈。VCR通过大幅减少头部旋转（<8Hz）和适度减少头部平移（>1Hz）对头在空间的稳定有贡献。CCR通过减少相对于躯干的头部旋转和平移（<2Hz）对头在躯干上的稳定有贡献。CCR对于稳定各个椎间关节和防止颈部屈曲也被证明是必不可少的。共同收缩被估计相关性较小。在低带宽扰动期间采用的控制策略最有效地减少了高达3Hz的头部旋转和头部相对位移，而在高带宽扰动期间采用的控制策略减少了1至4Hz之间的头部整体平移。这表明从在低带宽扰动期间最小化头在躯干上的旋转和平移转变为在高带宽扰动期间最小化头在空间的平移。视觉反馈的存在影响有限，表明前庭反馈的使用增加。
