Brugger P, Kollias S S, Müri R M, Crelier G, Hepp-Reymond M C, Regard M
Department of Neurology and Institute of Neuroradiology, University Hospital Zürich, CH-8091 Zürich, Switzerland.
Proc Natl Acad Sci U S A. 2000 May 23;97(11):6167-72. doi: 10.1073/pnas.100510697.
Phantom limbs are traditionally conceptualized as the phenomenal persistence of a body part after deafferentation. Previous clinical observations of subjects with phantoms of congenitally absent limbs are not compatible with this view, but, in the absence of experimental work, the neural basis of such "aplasic phantoms" has remained enigmatic. In this paper, we report a series of behavioral, imaging, and neurophysiological experiments with a university-educated woman born without forearms and legs, who experiences vivid phantom sensations of all four limbs. Visuokinesthetic integration of tachistoscopically presented drawings of hands and feet indicated an intact somatic representation of these body parts. Functional magnetic resonance imaging of phantom hand movements showed no activation of primary sensorimotor areas, but of premotor and parietal cortex bilaterally. Movements of the existing upper arms produced activation expanding into the hand territories deprived of afferences and efferences. Transcranial magnetic stimulation of the sensorimotor cortex consistently elicited phantom sensations in the contralateral fingers and hand. In addition, premotor and parietal stimulation evoked similar phantom sensations, albeit in the absence of motor evoked potentials in the stump. These data indicate that body parts that have never been physically developed can be represented in sensory and motor cortical areas. Both genetic and epigenetic factors, such as the habitual observation of other people moving their limbs, may contribute to the conscious experience of aplasic phantoms.
传统上，幻肢被概念化为身体部分在去传入神经后现象学上的持续存在。先前对先天性肢体缺失幻肢患者的临床观察与这一观点不符，但在缺乏实验研究的情况下，这种“发育不全幻肢”的神经基础一直成谜。在本文中，我们报告了一系列行为、成像和神经生理学实验，实验对象是一名受过大学教育、生来没有前臂和双腿的女性，她能清晰地感觉到四肢的幻肢感觉。对手和脚的速视呈现图形进行视觉动觉整合表明，这些身体部位的躯体表征是完整的。对幻肢手部运动的功能磁共振成像显示，初级感觉运动区未被激活，而是双侧的运动前区和顶叶皮质被激活。现有上臂的运动会产生激活，延伸到缺乏传入和传出神经的手部区域。对感觉运动皮质进行经颅磁刺激始终会在对侧手指和手部引发幻肢感觉。此外，对运动前区和顶叶的刺激也会引发类似的幻肢感觉，尽管残肢中没有运动诱发电位。这些数据表明，从未实际发育过的身体部位也可以在感觉和运动皮质区域得到表征。遗传和表观遗传因素，比如习惯性观察他人肢体运动，可能都对发育不全幻肢的有意识体验有影响。
