Miall R Chris, Kitchen Nick M, Nam Se-Ho, Lefumat Hannah, Renault Alix G, Ørstavik Kristin, Cole Jonathan D, Sarlegna Fabrice R
School of Psychology, University of Birmingham, Birmingham, B15 2TT, UK.
Department of Neuroscience, University of Pennsylvania, Philadelphia, USA.
Exp Brain Res. 2018 Aug;236(8):2137-2155. doi: 10.1007/s00221-018-5289-0. Epub 2018 May 19.
It is uncertain how vision and proprioception contribute to adaptation of voluntary arm movements. In normal participants, adaptation to imposed forces is possible with or without vision, suggesting that proprioception is sufficient; in participants with proprioceptive loss (PL), adaptation is possible with visual feedback, suggesting that proprioception is unnecessary. In experiment 1 adaptation to, and retention of, perturbing forces were evaluated in three chronically deafferented participants. They made rapid reaching movements to move a cursor toward a visual target, and a planar robot arm applied orthogonal velocity-dependent forces. Trial-by-trial error correction was observed in all participants. Such adaptation has been characterized with a dual-rate model: a fast process that learns quickly, but retains poorly and a slow process that learns slowly and retains well. Experiment 2 showed that the PL participants had large individual differences in learning and retention rates compared to normal controls. Experiment 3 tested participants' perception of applied forces. With visual feedback, the PL participants could report the perturbation's direction as well as controls; without visual feedback, thresholds were elevated. Experiment 4 showed, in healthy participants, that force direction could be estimated from head motion, at levels close to the no-vision threshold for the PL participants. Our results show that proprioceptive loss influences perception, motor control and adaptation but that proprioception from the moving limb is not essential for adaptation to, or detection of, force fields. The differences in learning and retention seen between the three deafferented participants suggest that they achieve these tasks in idiosyncratic ways after proprioceptive loss, possibly integrating visual and vestibular information with individual cognitive strategies.
视觉和本体感觉如何促进自愿性手臂运动的适应性尚不确定。在正常参与者中，无论有无视觉，都有可能适应施加的力，这表明本体感觉就足够了；在本体感觉丧失（PL）的参与者中，有视觉反馈时也能适应，这表明本体感觉并非必要。在实验1中，对三名长期去传入神经的参与者进行了对干扰力的适应和保持能力评估。他们进行快速伸手动作，将光标移向视觉目标，平面机器人手臂施加与速度相关的正交力。在所有参与者中都观察到了逐次试验的误差校正。这种适应已用双速率模型进行了描述：一个快速过程，学习快但保持差，以及一个缓慢过程，学习慢但保持好。实验2表明，与正常对照组相比，PL参与者在学习和保持率方面存在很大的个体差异。实验3测试了参与者对施加力的感知。有视觉反馈时，PL参与者能够像对照组一样报告干扰的方向；没有视觉反馈时，阈值会升高。实验4表明，在健康参与者中，可以根据头部运动估计力的方向，其水平接近PL参与者的无视觉阈值。我们的结果表明，本体感觉丧失会影响感知、运动控制和适应，但来自运动肢体的本体感觉对于适应或检测力场并非必不可少。三名去传入神经参与者在学习和保持方面的差异表明，他们在本体感觉丧失后以独特的方式完成这些任务，可能将视觉和前庭信息与个体认知策略相结合。
