Human Sensorimotor Control Laboratory, Center for Clinical Movement Science, School of Kinesiology, University of Minnesota Minneapolis, MN, USA.
Front Hum Neurosci. 2013 Jun 25;7:297. doi: 10.3389/fnhum.2013.00297. eCollection 2013.
Musician's dystonia (MD) is a neurological motor disorder characterized by involuntary contractions of those muscles involved in the play of a musical instrument. It is task-specific and initially only impairs the voluntary control of highly practiced musical motor skills. MD can lead to a severe decrement in a musician's ability to perform. While the etiology and the neurological pathomechanism of the disease remain unknown, it is known that MD like others forms of focal dystonia is associated with somatosensory deficits, specifically a decreased precision of tactile and proprioceptive perception. The sensory component of the disease becomes also evident by the patients' use of "sensory tricks" such as touching dystonic muscles to alleviate motor symptoms. The central premise of this paper is that the motor symptoms of MD have a somatosensory origin and are not fully explained as a problem of motor execution. We outline how altered proprioceptive feedback ultimately leads to a loss of voluntary motor control and propose two scenarios that explain why sensory tricks are effective. They are effective, because the sensorimotor system either recruits neural resources normally involved in tactile-proprioceptive (sensory) integration, or utilizes a fully functioning motor efference copy mechanism to align experienced with expected sensory feedback. We argue that an enhanced understanding of how a primary sensory deficit interacts with mechanisms of sensorimotor integration in MD provides helpful insights for the design of more effective behavioral therapies.
音乐家手痉挛（MD）是一种神经系统运动障碍，其特征是演奏乐器时相关肌肉出现不自主收缩。它具有任务特异性，最初仅损害高度熟练的音乐运动技能的自愿控制。MD 可导致音乐家演奏能力严重下降。虽然该病的病因和神经病理机制尚不清楚，但已知 MD 与其他形式的局灶性肌张力障碍一样，与体感缺陷有关，特别是触觉和本体感觉感知的准确性降低。通过患者使用“感觉技巧”（例如触摸痉挛肌肉以缓解运动症状），也可以明显看出疾病的感觉成分。本文的中心前提是，MD 的运动症状具有体感起源，不能完全解释为运动执行问题。我们概述了感觉反馈的改变如何最终导致自愿运动控制的丧失，并提出了两种解释感觉技巧为何有效的情况。这些技巧之所以有效，是因为感觉运动系统要么募集了正常参与触觉-本体感觉（感觉）整合的神经资源，要么利用完全正常运作的运动传出副本机制来使体验到的感觉反馈与预期的感觉反馈保持一致。我们认为，对手痉挛中主要感觉缺陷与感觉运动整合机制相互作用的更深入理解，为设计更有效的行为疗法提供了有益的见解。
