Weeks Heidi M, Therrien Amanda S, Bastian Amy J
Department of Biomedical Engineering, The Johns Hopkins School of Medicine, Baltimore, Maryland.
Kennedy Krieger Institute, Baltimore, Maryland; and.
J Neurophysiol. 2017 Aug 1;118(2):693-702. doi: 10.1152/jn.00417.2016. Epub 2017 Apr 12.
Proprioception, the sense of limb position and motion, is essential for generating accurate movements. Limb position sense has typically been studied under static conditions (i.e., the fixed position of a limb in space), with less known about dynamic position sense (i.e., limb position during movement). Here we investigated how a person's estimate of hand position varies when using spatial or temporal information to judge the unseen hand's location during reaching. We assessed the acuity of dynamic position sense in two directions, orthogonal to hand movement, which only requires spatial information, and in line with hand movement, which has both spatial and temporal components. Our results showed that people have better proprioceptive acuity in the orthogonal condition where only spatial information is used. We then assessed whether cerebellar damage impairs proprioceptive acuity in both tasks during passive and active movement. Cerebellar patients showed reduced acuity in both tasks and in both movement conditions relative to age-matched controls. However, patients' deficits were most apparent when judgments of active movement relied on temporal information. Furthermore, both cerebellar patient and control performance correlated with the trial-to-trial variability of their active movements: subjects are worse at the proprioceptive tasks when movements are variable. Our results suggest that, during active movements, proprioceptive acuity may be reliant on the motor system's ability to predict motor output. Therefore, the resultant proprioceptive deficits occurring after cerebellar damage may be related to a more general impairment in movement prediction. We assessed limb position sense during movement in patients with cerebellar damage and found deficits in proprioceptive acuity during both passive and active movement. The effect of cerebellar damage was most apparent when individuals relied on both timing and spatial information during active movement. Thus proprioceptive acuity during active movements may be reliant on the motor system's ability to predict motor output.
本体感觉，即肢体位置和运动的感觉，对于产生精确的动作至关重要。肢体位置感觉通常是在静态条件下（即肢体在空间中的固定位置）进行研究的，而对于动态位置感觉（即运动过程中的肢体位置）了解较少。在这里，我们研究了在伸手过程中，当人们使用空间或时间信息来判断看不见的手的位置时，对手部位置的估计是如何变化的。我们在与手部运动正交的两个方向上评估了动态位置感觉的敏锐度，这只需要空间信息，以及与手部运动一致的方向上，这既有空间成分也有时间成分。我们的结果表明，在仅使用空间信息的正交条件下，人们具有更好的本体感觉敏锐度。然后，我们评估了小脑损伤是否会在被动和主动运动的两项任务中损害本体感觉敏锐度。与年龄匹配的对照组相比，小脑病变患者在两项任务和两种运动条件下的敏锐度均降低。然而，当主动运动的判断依赖于时间信息时，患者的缺陷最为明显。此外，小脑病变患者和对照组的表现都与他们主动运动的逐次试验变异性相关：当运动变化时，受试者在本体感觉任务上表现更差。我们的结果表明，在主动运动过程中，本体感觉敏锐度可能依赖于运动系统预测运动输出的能力。因此，小脑损伤后出现的本体感觉缺陷可能与运动预测方面更普遍的损伤有关。我们评估了小脑损伤患者运动过程中的肢体位置感觉，发现被动和主动运动过程中本体感觉敏锐度均有缺陷。当个体在主动运动中依赖时间和空间信息时，小脑损伤的影响最为明显。因此，主动运动过程中的本体感觉敏锐度可能依赖于运动系统预测运动输出的能力。
