Nikaido Yasutaka, Hatanaka Ryota, Jono Yasutomo, Nomura Yoshifumi, Tani Keisuke, Chujo Yuta, Hiraoka Koichi
Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, Japan.
College of Health and Human Sciences, Osaka Prefecture University, Japan.
Hum Mov Sci. 2016 Jun;47:38-48. doi: 10.1016/j.humov.2016.01.016. Epub 2016 Feb 5.
This study investigated time and direction preparation of motor response to force load while intending to maintain the finger at the initial neutral position. Force load extending or flexing the index finger was given while healthy humans intended to maintain the index finger at the initial neutral position. Electromyographic activity was recorded from the first dorsal interosseous muscle. A precue with or without advanced information regarding the direction of the forthcoming force load was given 1000ms before force load. Trials without the precue were inserted between the precued trials. A long latency stretch reflex was elicited by force load regardless of its direction, indicating that the long latency stretch reflex is elicited not only by muscle stretch afferents, but also by direction-insensitive sensations. Time preparation of motor response to either direction of force load enhanced the long latency stretch reflex, indicating that time preparation is not mediated by afferent discharge of muscle stretch. Direction preparation enhanced the long latency stretch reflex and increased corticospinal excitability 0-20ms after force load when force load was given in the direction stretching the muscle. These enhancements must be induced by preset of the afferent pathway mediating segmental stretch reflex.
本研究调查了在意图将手指保持在初始中立位置时，对力负荷的运动反应的时间和方向准备情况。在健康人意图将食指保持在初始中立位置时，施加使食指伸展或弯曲的力负荷。从第一背侧骨间肌记录肌电图活动。在施加力负荷前1000毫秒给予关于即将到来的力负荷方向的有或无提前信息的预提示。在有预提示的试验之间插入无预提示的试验。无论力负荷方向如何，力负荷都会引发长潜伏期牵张反射，这表明长潜伏期牵张反射不仅由肌肉牵张传入引起，还由方向不敏感的感觉引起。对力负荷任一方向的运动反应的时间准备增强了长潜伏期牵张反射，表明时间准备不是由肌肉牵张的传入放电介导的。当力负荷沿伸展肌肉的方向施加时，方向准备增强了长潜伏期牵张反射，并在力负荷后0 - 20毫秒增加了皮质脊髓兴奋性。这些增强一定是由介导节段性牵张反射的传入通路的预设引起的。
