Sanders Ozell P, Savin Douglas N, Creath Robert A, Rogers Mark W
Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Department of Physical Therapy and Rehabilitation Science, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Neurosci Lett. 2015 Jan 23;586:8-12. doi: 10.1016/j.neulet.2014.11.034. Epub 2014 Nov 29.
The aim of the present study was to investigate whether or not startle reactions contribute to the whole body postural responses following sudden freefall in standing humans. Nine healthy participants stood atop a moveable platform and received externally-triggered (EXT) and selftriggered (SLF) drop perturbations of the support surface. Electromyographic (EMG) activity was recorded bilaterally over the sternocleidomastoid (SCM), deltoid (DLT), biceps brachii (BIC), medial gastrocnemius (GAS), and tibialis anterior (TA) muscles. Whole-body kinematics were also recorded with motion analysis. Rapid phasic activation of SCM during the first trial response (FTR) was seen for all participants for EXT and for 56% of subjects for SLF. Reductions in EMG amplitude between the EXT FTR and later trial responses for SCM, DLT, and BIC and reduced arm movement acceleration indicative of habituation occurred and exceeded adaptive reductions for SLF. These findings suggested that a startle reflex contributes to the exaggerated postural FTR observed during externally-triggered whole-body free falls.
本研究的目的是调查惊吓反应是否有助于站立的人体突然自由落体后的全身姿势反应。九名健康参与者站在一个可移动的平台上，接受支撑面的外部触发（EXT）和自我触发（SLF）下落扰动。双侧记录胸锁乳突肌（SCM）、三角肌（DLT）、肱二头肌（BIC）、腓肠肌内侧头（GAS）和胫骨前肌（TA）的肌电图（EMG）活动。还通过运动分析记录全身运动学。在第一次试验反应（FTR）期间，所有参与者的EXT以及56%的受试者的SLF都出现了SCM的快速相位激活。EXT FTR与SCM、DLT和BIC的后续试验反应之间的EMG振幅降低，以及表明习惯化的手臂运动加速度降低，且超过了SLF的适应性降低。这些发现表明，惊吓反射有助于在外部触发的全身自由落体期间观察到的夸张姿势FTR。
