Roberts James W, Wakefield Caroline J, Owen Robin
Brain & Behaviour Research Group, Research Institute of Sport & Exercise Sciences (RISES), Liverpool John Moores University, Tom Reilly Building, Byrom Street, Liverpool, L3 5AF, UK.
School of Health and Sport Sciences, Liverpool Hope University, Hope Park, Liverpool, L16 9JD, UK.
Exp Brain Res. 2024 Dec 2;243(1):9. doi: 10.1007/s00221-024-06951-3.
Motor imagery and execution often indicate a similar trend in the temporal characteristics of movements. This finding supports the notion of functional equivalence, whereby imagery and execution use a common neural representation. However, there is comparatively limited evidence related to the spatial characteristics of movements; no doubt owing to the absence of an actual spatial trajectory during imagery. Therefore, we adapted the trajectory priming paradigm involving an obstacle, where the trajectory adopted in a trial (n) is directly contaminated by a previous trial (n-1). If imagery accurately represents the spatial characteristics, then we would predict a similar priming effect as execution. Participants completed a series of trial blocks under different imagery/execution protocols, where the test trial (n) comprised execution alone, while the previous trial (n-1) involved imagery or execution. Each block comprised pairs of trials with alternate or consistent presentations of a virtual obstacle (O) or no obstacle (N): N-N, N-O, O-N, O-O. For trial n-1 (imagery/execution), there was a more prolonged reaction and movement time for imagery compared execution. Most importantly for trial n (execution), there was an increase in early angular and peak deviation following an obstacle compared to no obstacle in trial n-1, but only when it was execution and not imagery. These findings suggest imagery holds a limited representation of the spatial characteristics, while functional equivalence may be limited to the temporal characteristics.
运动想象和运动执行在运动的时间特征方面往往呈现出相似的趋势。这一发现支持了功能等效性的概念，即想象和执行使用共同的神经表征。然而，与运动的空间特征相关的证据相对有限；这无疑是由于在想象过程中缺乏实际的空间轨迹。因此，我们采用了涉及障碍物的轨迹启动范式，其中试验（n）中采用的轨迹直接受到前一次试验（n-1）的影响。如果想象准确地代表了空间特征，那么我们可以预测会出现与执行类似的启动效应。参与者在不同的想象/执行协议下完成了一系列试验块，其中测试试验（n）仅包括执行，而前一次试验（n-1）涉及想象或执行。每个块由成对的试验组成，虚拟障碍物（O）或无障碍物（N）交替或一致呈现：N-N、N-O、O-N、O-O。对于试验n-1（想象/执行），与执行相比，想象的反应时间和运动时间更长。对于试验n（执行）最重要的是，与试验n-1中无障碍物相比，有障碍物时早期角度和峰值偏差增加，但仅当是执行而非想象时。这些发现表明，想象对空间特征的表征有限，而功能等效性可能仅限于时间特征。
