Perenboom M J L, Van de Ruit M, De Groot J H, Schouten A C, Meskers C G M
Department of Rehabilitation Medicine, Leiden University Medical Center B0-Q, P.O. Box 9600, 2300 RC Leiden, The Netherlands; Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, 2628 CD Delft, The Netherlands.
Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, 2628 CD Delft, The Netherlands; School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
Neurosci Lett. 2015 Jan 1;584:214-8. doi: 10.1016/j.neulet.2014.10.034. Epub 2014 Oct 24.
Adaptation of reflexes to environment and task at hand is a key mechanism in optimal motor control, possibly regulated by the cortex. In order to locate the corticospinal integration, i.e. spinal or supraspinal, and to study the critical temporal window of reflex adaptation, we combined transcranial magnetic stimulation (TMS) and upper extremity muscle stretch reflexes at high temporal precision. In twelve participants (age 49 ± 13 years, eight male), afferent signals were evoked by 40 ms ramp and subsequent hold stretches of the m. flexor carpi radialis (FCR). Motor conduction delays (TMS time of arrival at the muscle) and TMS-motor threshold were individually assessed. Subsequently TMS pulses at 96% of active motor threshold were applied with a resolution of 5-10 ms between 10 ms before and 120 ms after onset of series of FCR stretches. Controlled for the individually assessed motor conduction delay, subthreshold TMS was found to significantly augment EMG responses between 60 and 90 ms after stretch onset. This sensitive temporal window suggests a cortical integration consistent with a long latency reflex period rather than a spinal integration consistent with a short latency reflex period. The potential cortical role in reflex adaptation extends over the full long latency reflex period, suggesting adaptive mechanisms beyond reflex onset.
反射对环境和手头任务的适应是最佳运动控制的关键机制，可能受皮层调节。为了确定皮质脊髓整合的位置，即脊髓或脊髓以上水平，并研究反射适应的关键时间窗，我们以高时间精度结合了经颅磁刺激（TMS）和上肢肌肉牵张反射。在12名参与者（年龄49±13岁，8名男性）中，通过对桡侧腕屈肌（FCR）进行40毫秒的斜坡式及随后的持续拉伸来诱发传入信号。分别评估运动传导延迟（TMS到达肌肉的时间）和TMS运动阈值。随后，在FCR系列拉伸开始前10毫秒至开始后120毫秒之间，以5 - 10毫秒的分辨率施加处于主动运动阈值96%的TMS脉冲。在控制了个体评估的运动传导延迟后，发现阈下TMS在拉伸开始后60至90毫秒之间显著增强肌电图反应。这个敏感的时间窗表明是皮层整合，符合长潜伏期反射期，而非符合短潜伏期反射期的脊髓整合。皮层在反射适应中的潜在作用延伸至整个长潜伏期反射期，提示了反射起始之外的适应性机制。
