Experimental Psychology, Justus Liebig University Giessen, Giessen, Germany.
J Neurophysiol. 2023 Jul 1;130(1):104-116. doi: 10.1152/jn.00024.2023. Epub 2023 Jun 7.
Pupillary responses have been reliably identified for cognitive and motor tasks, but less is known about their relation to mentally simulated movements (known as motor imagery). Previous work found pupil dilations during the execution of simple finger movements, where peak pupillary dilation scaled with the complexity of the finger movement and force required. Recently, pupillary dilations were reported during imagery of grasping and piano playing. Here, we examined whether pupillary responses are sensitive to the dynamics of the underlying motor task for both executed and imagined reach movements. Participants reached or imagined reaching to one of three targets placed at different distances from a start position. Both executed and imagined movement times scaled with target distance, and they were highly correlated, confirming previous work and suggesting that participants did imagine the respective movement. Increased pupillary dilation was evident during motor execution compared with rest, with stronger dilations for larger movements. Pupil dilations also occurred during motor imagery, however, they were generally weaker than those during motor execution and they were not influenced by imagined movement distance. Instead, dilations during motor imagery resembled pupil responses obtained during a nonmotor imagery task (imagining a previously viewed painting). Our results demonstrate that pupillary responses can reliably capture the dynamics of an executed goal-directed reaching movement, but suggest that pupillary responses during imagined reaching movements reflect general cognitive processes, rather than motor-specific components related to the simulated dynamics of the sensorimotor system. Pupil size is influenced by the performance of cognitive and motor tasks. Here, we demonstrate that pupil size increases not only during execution but also during mental simulation of goal-directed reaching movements. However, pupil dilations scale with movement amplitude of executed but not of imagined movement, whereas they are similar during motor imagery and a nonmotor imagery task.
瞳孔反应已被可靠地识别为认知和运动任务，但对于它们与心理模拟运动（称为运动想象）的关系知之甚少。以前的工作发现，在执行简单的手指运动时，瞳孔会扩张，而瞳孔扩张的峰值与手指运动的复杂性和所需的力成正比。最近，在抓握和弹钢琴的想象中报告了瞳孔扩张。在这里，我们研究了瞳孔反应是否对执行和想象的伸手运动的基础运动任务的动态敏感。参与者伸手或想象伸手去触及从起始位置放置在不同距离的三个目标之一。执行和想象的运动时间都与目标距离成比例，并且它们高度相关，这证实了以前的工作并表明参与者确实想象了各自的运动。与休息相比，在运动执行过程中瞳孔明显扩张，较大的运动瞳孔扩张更大。在运动想象过程中也发生了瞳孔扩张，但是，它们通常比运动执行时的瞳孔扩张弱，并且不受想象运动距离的影响。相反，运动想象过程中的瞳孔扩张类似于在非运动想象任务（想象之前观看过的画作）中获得的瞳孔反应。我们的结果表明，瞳孔反应可以可靠地捕捉执行的目标导向伸手运动的动态，但表明想象中的伸手运动期间的瞳孔反应反映了一般的认知过程，而不是与感觉运动系统的模拟动态相关的运动特定成分。瞳孔大小受认知和运动任务的影响。在这里，我们证明不仅在执行过程中，而且在目标导向的伸手运动的心理模拟过程中，瞳孔大小也会增加。然而，瞳孔扩张与执行的运动幅度成正比，但与想象的运动不成比例，而在运动想象和非运动想象任务中则相似。
