Human Cortical Physiology and Motor Control Laboratory, Department of Neurology, University of Wuerzburg, D-97080 Wuerzburg, Germany.
Brain. 2011 May;134(Pt 5):1428-37. doi: 10.1093/brain/awr026. Epub 2011 Mar 4.
Patients with dystonia display a number of disturbances in the cognitive processing of movements, such as movement simulation and prediction, but whether these deficits point to a deeper rooted disturbance of perceptual bodily representations remains unknown. A useful way to investigate the sense of body ownership is the rubber hand paradigm, in which an illusion of ownership is established by synchronous stroking of the participants' real unseen hand and a visible fake hand, whereas similar asynchronous stroking does not bring about the illusion. This paradigm allows testing of both the subjective experience of feeling ownership over the rubber hand and the proprioceptive relocation of the real unseen hand towards the viewed rubber hand. Previous studies have mapped these different aspects onto two anatomically distinct neuronal substrates, with the ventral premotor cortex processing the illusory feeling of ownership and the inferior parietal lobule and cerebellum processing proprioceptive drift. We applied the rubber hand illusion task to healthy subjects and to patients affected by two different types of focal dystonia-one specifically affecting the hand (focal hand dystonia) and one not affecting the hand (torticollis and blepharospasm). Results showed that in patients with focal hand dystonia, the proprioceptive drift was selectively disrupted on the dystonic hand while the subjective experience of the illusion was retained. In the non-dystonic hand and in the other two groups (non-hand dystonia and healthy subjects), the rubber hand illusion resembled the typical pattern with synchronous stroking eliciting the illusion. These findings provide support for the contention that the mechanisms underlying the presence of the illusory feeling of ownership and the proprioceptive drift are different. Selective impairment of the limb recalibration on the dystonic hand points to underlying deficits in integrating the visual-tactile input with the proprioceptive information in order to update the current body position and may support a model linking dystonia to dysfunctions in a network comprising the inferior parietal cortex and the cerebellum.
患有肌张力障碍的患者在运动的认知处理中表现出许多障碍，例如运动模拟和预测，但这些缺陷是否指向更深层次的感知身体表象的障碍尚不清楚。一种研究身体所有权感觉的有用方法是橡胶手范式，通过对参与者真实看不见的手和可见的假手进行同步stroking，可以建立所有权的错觉，而类似的异步stroking则不会产生错觉。该范式允许测试对橡胶手的感觉所有权的主观体验以及对所看到的橡胶手的真实看不见的手的本体感受重定位。先前的研究将这些不同的方面映射到两个解剖上不同的神经元基质上，腹侧运动前皮层处理虚幻的所有权感觉，而下顶叶和小脑处理本体感受漂移。我们将橡胶手错觉任务应用于健康受试者和两种不同类型的局灶性肌张力障碍患者——一种专门影响手部（局灶性手部肌张力障碍），另一种不影响手部（斜颈和眼睑痉挛）。结果表明，在局灶性手部肌张力障碍患者中，手部的本体感受漂移选择性地受到干扰，而错觉的主观体验得以保留。在非手部和其他两组（非手部肌张力障碍和健康受试者）中，橡胶手错觉类似于典型模式，同步stroking 引起错觉。这些发现为以下观点提供了支持，即产生虚幻的所有权感觉和本体感受漂移的机制是不同的。在痉挛的手上，肢体重新校准的选择性损伤表明，在整合视觉触觉输入与本体感觉信息以更新当前身体位置方面存在潜在缺陷，这可能支持一种将肌张力障碍与包括下顶叶皮层和小脑在内的网络功能障碍联系起来的模型。
