Maslovat Dana, Carter Michael J, Carlsen Anthony N
School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.
Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada; and.
J Neurophysiol. 2017 Sep 1;118(3):1720-1731. doi: 10.1152/jn.00323.2017. Epub 2017 Jun 28.
During continuous bimanual coordination, in-phase (IP; 0° relative phase) and anti-phase (AP; 180° relative phase) patterns can be stably performed without practice. Paradigms in which participants are required to intentionally switch between these coordination patterns have been used to investigate the interaction between the performer's intentions and intrinsic dynamics of the body's preferred patterns. The current study examined the processes associated with switching preparation and execution through the use of a startling acoustic stimulus (SAS) as the switch stimulus. A SAS is known to involuntarily trigger preprogrammed responses at a shortened latency and, thus, can be used to probe advance preparation. Participants performed cyclical IP and AP bimanual elbow extension-flexion movements in which they were required to switch patterns in response to an auditory switch cue, which was either nonstartling (80 dB) or a SAS (120 dB). Results indicated that reaction time to the switch stimulus (i.e., switch onset) was significantly reduced on startle trials, indicative of advance preparation of the switch response. Similarly, switching time was reduced on startle trials, which was attributed to increased neural activation caused by the SAS. Switching time was also shorter for AP to IP trials, but only when the switching stimulus occurred at either the midpoint or reversal locations within the movement cycle, suggesting that the switch location may affect the intrinsic dynamics of the system. The current study provides novel information regarding preparation and execution of intentional switching between in-phase and anti-phase bimanual coordination patterns. Using a startling acoustic stimulus, we provide strong evidence that the switching response is prepared before the switch stimulus, and switch execution is accelerated by the startling stimulus. In addition, the time required to switch between patterns and relative limb contribution is dependent upon where in the movement cycle the switch stimulus occurred.
在持续的双手协调过程中，同相（IP；相对相位0°）和反相（AP；相对相位180°）模式无需练习即可稳定执行。要求参与者在这些协调模式之间有意切换的范式已被用于研究执行者的意图与身体偏好模式的内在动力学之间的相互作用。本研究通过使用惊人的听觉刺激（SAS）作为切换刺激，考察了与切换准备和执行相关的过程。已知SAS会在缩短的潜伏期内非自愿地触发预编程反应，因此可用于探测提前准备情况。参与者进行周期性的IP和AP双手肘部屈伸运动，他们需要根据听觉切换提示（非惊人的80 dB或SAS的120 dB）切换模式。结果表明，在惊吓试验中，对切换刺激（即切换开始）的反应时间显著缩短，这表明对切换反应有提前准备。同样，惊吓试验中的切换时间也缩短了，这归因于SAS引起的神经激活增加。从AP到IP试验的切换时间也较短，但仅当切换刺激出现在运动周期的中点或反转位置时，这表明切换位置可能会影响系统的内在动力学。本研究提供了关于同相和反相双手协调模式之间有意切换的准备和执行的新信息。通过使用惊人的听觉刺激，我们提供了有力证据，表明切换反应在切换刺激之前就已准备好，并且惊人刺激加速了切换执行。此外，模式之间切换所需的时间和相对肢体贡献取决于切换刺激在运动周期中的位置。
