Marinovic Welber, Flannery Victoria, Riek Stephan
Centre for Sensorimotor Performance, School of Human Movement Studies, The University of Queensland, Australia; School of Psychology, The University of Queensland, Australia.
School of Psychology, The University of Queensland, Australia.
Hum Mov Sci. 2015 Aug;42:81-8. doi: 10.1016/j.humov.2015.05.003. Epub 2015 May 15.
A loud auditory stimulus (LAS) presented together with an imperative stimulus during preparation for motor actions can speed their initiation. The effects of LAS on corticospinal excitability (CSE), however, depend on the state of preparation of the motor system for action. CSE also depends on the brain hemisphere controlling the responding limb. Usually, CSE is increased just before movement onset in the hemisphere controlling the movement and inhibited on the other side. This study investigated the impact of LAS on CSE of the contralateral and ipsilateral hemispheres, while participants prepared for a voluntary abduction of the index finger. In Experiment 1, we attempted to identify the pattern of modulation of the ipsilateral cortex (resting side) by determining the time course of corticospinal changes in anticipatory timing actions using transcranial magnetic stimulation. In Experiment 2, we investigated the impact of LAS on the ipsilateral and contralateral CSE during anticipatory preparation. Results found no modulation of ipsilateral CSE during preparation, but indicate an increase in CSE after EMG onset on the acting limb. Moreover, we found that LAS presentation increased CSE on the contralateral side (active side).
在准备进行运动动作时，与指令性刺激同时呈现的大声听觉刺激（LAS）可以加快动作的启动。然而，LAS对皮质脊髓兴奋性（CSE）的影响取决于运动系统对动作的准备状态。CSE还取决于控制做出反应肢体的脑半球。通常，在控制运动的半球中，CSE在运动开始前会增加，而在另一侧则受到抑制。本研究在参与者准备自愿外展食指时，调查了LAS对同侧和对侧半球CSE的影响。在实验1中，我们试图通过使用经颅磁刺激确定预期定时动作中皮质脊髓变化的时间进程，来识别同侧皮质（静止侧）的调制模式。在实验2中，我们研究了LAS在预期准备期间对同侧和对侧CSE的影响。结果发现，准备期间同侧CSE没有调制，但表明在动作肢体的肌电图开始后CSE增加。此外，我们发现呈现LAS会增加对侧（活动侧）的CSE。
