Desmurget M, Vindras P, Gréa H, Viviani P, Grafton S T
Department of Neurology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Exp Brain Res. 2000 Oct;134(3):363-77. doi: 10.1007/s002210000473.
Several perceptual studies have shown that the ability to estimate the location of the arm degrades quickly during visual occlusion. To account for this effect, it has been suggested that proprioception drifts when not continuously calibrated by vision. In the present study, we re-evaluated this hypothesis by isolating the proprioceptive component of position sense (i.e., the subjects were forced to rely exclusively on proprioception to locate their hand, which was not the case in earlier studies). Three experiments were conducted. In experiment 1, subjects were required to estimate the location of their unseen right hand, at rest, using a visual spot controlled by the left hand through a joystick. Results showed that the mean accuracy was identical whether the localization task was performed immediately after the positioning of the hand or after a 10-s delay. In experiments 2 and 3, subjects were required to point, without vision of their limb, to visual targets. These two experiments relied on the demonstration that biases in the perception of the initial hand location induced systematic variations of the movement characteristics (initial direction, final accuracy, end-point variability). For these motor tasks, the subjects did not pay attention to the initial hand location, which removed the possible occurrence of confounding cognitive strategies. Results indicated that movement characteristics were, on average, not affected when a 15-s or 20-s delay was introduced between the positioning of the arm at the starting point and the presentation of the target. When considered together, our results suggest that proprioception does not quickly drift in the absence of visual information. The potential origin of the discrepancy between our results and earlier studies is discussed.
多项知觉研究表明，在视觉遮挡期间，估计手臂位置的能力会迅速下降。为了解释这种效应，有人提出，当本体感觉没有通过视觉持续校准时就会发生漂移。在本研究中，我们通过分离位置感的本体感觉成分（即，受试者被迫完全依靠本体感觉来定位他们的手，早期研究中并非如此）重新评估了这一假设。进行了三项实验。在实验1中，要求受试者使用由左手通过操纵杆控制的视觉光点来估计其静止时看不见的右手的位置。结果表明，无论是在手部定位后立即执行定位任务还是在延迟10秒后执行，平均准确率都是相同的。在实验2和3中，要求受试者在看不到肢体的情况下指向视觉目标。这两项实验依赖于这样一个证明，即对手部初始位置的感知偏差会引起运动特征（初始方向、最终准确性、终点变异性）的系统性变化。对于这些运动任务，受试者没有关注手部的初始位置，这消除了可能出现的混淆认知策略。结果表明，在手臂在起始点定位和目标呈现之间引入15秒或20秒的延迟时，运动特征平均不受影响。综合考虑，我们的结果表明，在没有视觉信息的情况下，本体感觉不会迅速漂移。我们讨论了我们的结果与早期研究之间差异的潜在原因。
