Zbib Basel, Henriques Denise Y P, Cressman Erin K
School of Human Kinetics, University of Ottawa, 125 University Private, Room 360, Ottawa, ON, K1N6N5, Canada.
School of Kinesiology and Health Science, York University, Toronto, Canada.
Exp Brain Res. 2016 Aug;234(8):2201-13. doi: 10.1007/s00221-016-4624-6. Epub 2016 Mar 25.
When subjects reach in a novel visuomotor environment (e.g. while viewing a cursor representing their hand that is rotated from their hand's actual position), they typically adjust their movements (i.e. bring the cursor to the target), thus reducing reaching errors. Additionally, research has shown that reaching with altered visual feedback of the hand results in sensory changes, such that proprioceptive estimates of hand position are shifted in the direction of the visual feedback experienced (Cressman and Henriques in J Neurophysiol 102:3505-3518, 2009). This study looked to establish the time course of these sensory changes. Additionally, the time courses of implicit sensory and motor changes were compared. Subjects reached to a single visual target while seeing a cursor that was either aligned with their hand position (50 trials) or rotated 30° clockwise relative to their hand (150 trials). Reach errors and proprioceptive estimates of felt hand position were assessed following the aligned reach training trials and at seven different times during the rotated reach training trials by having subjects reach to the target without visual feedback, and provide estimates of their hand relative to a visual reference marker, respectively. Results revealed a shift in proprioceptive estimates throughout the rotated reach training trials; however, significant sensory changes were not observed until after 70 trials. In contrast, results showed a greater change in reaches after a limited number of reach training trials with the rotated cursor. These findings suggest that proprioceptive recalibration arises more slowly than reach adaptation.
当受试者在新的视觉运动环境中伸手抓取（例如，观看代表其手部的光标，该光标相对于其手部实际位置发生了旋转）时，他们通常会调整自己的动作（即将光标移向目标），从而减少伸手抓取的误差。此外，研究表明，手部视觉反馈改变时的伸手抓取会导致感觉变化，使得手部位置的本体感觉估计朝着所体验到的视觉反馈方向偏移（Cressman和Henriques，《神经生理学杂志》102:3505 - 3518，2009年）。本研究旨在确定这些感觉变化的时间进程。此外，还比较了内隐感觉和运动变化的时间进程。受试者在观看与手部位置对齐的光标（50次试验）或相对于手部顺时针旋转30°的光标（150次试验）的同时，伸手抓取单个视觉目标。在对齐伸手抓取训练试验之后以及在旋转伸手抓取训练试验期间的七个不同时间点，通过让受试者在没有视觉反馈的情况下伸手抓取目标，并分别提供其手部相对于视觉参考标记的估计值，来评估伸手抓取误差和手部感觉位置的本体感觉估计。结果显示，在整个旋转伸手抓取训练试验过程中，本体感觉估计发生了偏移；然而，直到70次试验之后才观察到明显的感觉变化。相比之下，结果表明，在使用旋转光标进行有限次数的伸手抓取训练试验后，伸手抓取动作有更大的变化。这些发现表明，本体感觉重新校准的出现比伸手抓取适应更为缓慢。
