Klockgether T, Borutta M, Rapp H, Spieker S, Dichgans J
Department of Neurology, University of Tübingen, Germany.
Mov Disord. 1995 Jul;10(4):460-5. doi: 10.1002/mds.870100410.
Patients suffering from Parkinson's disease (PD) are more dependent on visual feedback during movement than are normals. Studying two-dimensional pointing movements, we recently found that PD patients undershoot targets when vision of their own moving hand is occluded but not when complete vision is provided or when the target is extinguished immediately before movement onset. In the absence of vision, information about position of the moving hand may originate from peripheral kinesthetic feedback and from corollary discharges derived from the efferent motor signal. To find out which of both mechanisms--kinesthetic feedback or corollary discharge--is defective in PD, we compared active movements with imposed movements in which the hand is passively moved by the experimenter, whereas vision of the hand was occluded under either condition. In agreement with our earlier findings, slow, active pointing movements of PD patients were hypometric. In addition, PD patients terminated passively imposed movements of comparable speed earlier than did normals, with the consequence that imposed movements were equally hypometric. Our results make it unlikely that disturbed corollary discharge is responsible for hypometria under nonvisual conditions. Instead, the data suggest that PD patients have a defect of kinesthesia in slowly executed movements.
帕金森病（PD）患者在运动过程中比正常人更依赖视觉反馈。在研究二维指向运动时，我们最近发现，当帕金森病患者自己移动的手的视觉被遮挡时，他们会指向目标下方，但当提供完整视觉或在运动开始前立即熄灭目标时则不会。在没有视觉的情况下，关于移动手的位置的信息可能来自外周动觉反馈以及源自传出运动信号的伴随放电。为了弄清楚在帕金森病中这两种机制——动觉反馈或伴随放电——哪一种存在缺陷，我们将主动运动与被动运动进行了比较，在被动运动中，手由实验者被动移动，而在两种情况下手的视觉都被遮挡。与我们早期的研究结果一致，帕金森病患者缓慢的主动指向运动是指距不足的。此外，帕金森病患者比正常人更早地终止了速度相当的被动施加运动，结果是被动施加运动同样指距不足。我们的结果表明，在非视觉条件下，伴随放电紊乱不太可能是指距不足的原因。相反，数据表明帕金森病患者在缓慢执行的运动中存在动觉缺陷。
