Carson R G
Department of Human Movement Studies, University of Queensland, Brisbane, Australia.
Exp Brain Res. 1996 Jun;110(1):99-110. doi: 10.1007/BF00241379.
Four right-handed subjects performed rhythmic flexion and extension movements of the index finger in time with an auditory metronome. On each block of trials the forearm of the response hand was placed in a prone, neutral or supine position. In the flex-on-the-beat condition, subjects were instructed to coordinate maximum excursion in the direction of finger flexion with each beat of the metronome. In the extend-on-the-beat condition, subjects were instructed to coordinate maximum excursion in the direction of finger extension with each beat of the metronome. The frequency of the metronome was increased from 1.75 Hz to 3.50 Hz in eight steps (8-s plateaus) of 0.25 Hz. During trials prepared in the extend-on-the-beat pattern or to phase wandering often occurred, particularly at higher pacing frequencies. In marked constrast, during trials prepared in the flex-on-the-beat pattern such transitions were never present. Both the frequency and the alacrity of these transitions were greater when the forearm was in a prone or neutral position than when the forearm was in a supine position. These results are discussed with reference to the constraints imposed on the coordination dynamics by the intrinsic properties of the neuromuscular-skeletal system.
四名右利手受试者随着听觉节拍器的节奏进行食指的节律性屈伸运动。在每组试验中，做出反应的手的前臂分别处于俯卧、中立或仰卧位置。在“节拍时屈曲”条件下，受试者被要求在节拍器的每一拍时，使手指屈曲方向的最大伸展幅度与之协调。在“节拍时伸展”条件下，受试者被要求在节拍器的每一拍时，使手指伸展方向的最大伸展幅度与之协调。节拍器的频率以0.25Hz的步长从1.75Hz增加到3.50Hz，共八个步骤（每个步骤持续8秒）。在按照“节拍时伸展”模式准备的试验过程中，尤其是在较高的起搏频率下，经常会出现向相位漂移的情况。与之形成鲜明对比的是，在按照“节拍时屈曲”模式准备的试验过程中，从未出现过这种转变。当受试者的前臂处于俯卧或中立位置时，这些转变的频率和敏捷程度都高于前臂处于仰卧位置时。我们将结合神经肌肉骨骼系统的内在特性对协调动力学施加的限制来讨论这些结果。
