Adkin Allan L, Campbell Adam D, Chua Romeo, Carpenter Mark G
Faculty of Applied Health Sciences, Brock University, Canada.
Neurosci Lett. 2008 Apr 18;435(2):120-5. doi: 10.1016/j.neulet.2008.02.018. Epub 2008 Feb 16.
This study investigated the effects of postural threat on the cortical response associated with postural reactions to predictable and unpredictable perturbations to upright stance. Postural threat was manipulated by having individuals stand on an elevated surface to alter the context in which the postural task was performed. Ten healthy young adults experienced a series of predictable and unpredictable trunk perturbations when standing at ground level and at the edge of a platform located 3.2 m above the ground. Participants felt less confident, more fearful of falling, more anxious and less stable when standing at the high surface height. Unpredictable perturbations generated a large negative potential (N1) which was increased by 84% when standing at the high compared to low surface height. The magnitude of change in this potential was related to the magnitude of change in balance perceptions, such as confidence and fear. Predictable perturbations did not generate a N1 potential but instead produced an anticipation-related potential prior to the perturbation. This cortical activity observed in response to predictable perturbations was not influenced by postural threat. A large N1 potential was observed for a 'surprise' perturbation that followed a series of predictable perturbations. There was a trend for the amplitude of this potential to be increased when standing at the high compared to low surface height. The results of this study provide evidence for the modulating influence of psychological factors related to postural threat on the cortical activity associated with postural reactions to unpredictable perturbations.
本研究调查了姿势威胁对与直立姿势可预测和不可预测扰动的姿势反应相关的皮质反应的影响。通过让个体站在升高的表面上来改变执行姿势任务的环境，从而操纵姿势威胁。10名健康的年轻成年人在地面以及离地面3.2米高的平台边缘站立时，经历了一系列可预测和不可预测的躯干扰动。当站在较高表面高度时，参与者感觉信心降低、更害怕摔倒、更焦虑且稳定性降低。不可预测的扰动产生了一个大的负电位（N1），与站在低表面高度相比，站在高表面高度时该负电位增加了84%。该电位的变化幅度与平衡感知（如信心和恐惧）的变化幅度相关。可预测的扰动未产生N1电位，而是在扰动之前产生了一个与预期相关的电位。观察到的对可预测扰动的这种皮质活动不受姿势威胁的影响。对于一系列可预测扰动之后的“意外”扰动，观察到一个大的N1电位。与站在低表面高度相比，站在高表面高度时该电位的幅度有增加的趋势。本研究结果为与姿势威胁相关的心理因素对与不可预测扰动的姿势反应相关的皮质活动的调节影响提供了证据。
