Table_1_Changes in primary somatosensory cortex following allogeneic hand transplantation or autogenic hand replantation.DOCX

Former amputees who undergo allogeneic hand transplantation or autogenic hand replantation (jointly, “hand restoration”) present a unique opportunity to measure the range of post-deafferentation plastic changes in the nervous system, especially primary somatosensory cortex (S1). However, few such patients exist, and previous studies compared single cases to small groups of typical adults. Here, we studied 5 individuals (n = 8 sessions: a transplant with 2 sessions, a transplant with 3 sessions, and three replants with 1 session each). We used functional magnetic resonance imaging (fMRI) to measure S1 responsiveness to controlled pneumatic tactile stimulation delivered to each patient's left and right fingertips and lower face. These data were compared with responses acquired from typical adults (n = 29) and current unilateral amputees (n = 19). During stimulation of the affected hand, patients' affected S1 (contralateral to affected hand) responded to stimulation in a manner similar both to amputees and to typical adults. The presence of contralateral responses indicated grossly typical S1 function, but responses were universally at the low end of the range of typical variability. Patients' affected S1 showed substantial individual variability in responses to stimulation of the intact hand: while all patients fell within the range of typical adults, some patient sessions (4/8) had substantial ipsilateral responses similar to those exhibited by current amputees. Unlike hand restoration patients, current amputees exhibited substantial S1 reorganization compared to typical adults, including bilateral S1 responses to stimulation of the intact hand. In all three participant groups, we assessed tactile localization by measuring individuals' ability to identify the location of touch on the palm and fingers. Curiously, while transplant patients improved their tactile sensory localization over time, this was uncorrelated with changes in S1 responses to tactile stimuli. Overall, our results provide the first description of cortical responses to well-controlled tactile stimulation after hand restoration. Our case studies indicate that hand restoration patients show S1 function within the range of both typical adults and amputees, but with low-amplitude and individual-specific responses that indicate a wide range of potential cortical neurological changes following de-afferentation and re-afferentation.

接受同种异体手移植（allogeneic hand transplantation）或自体手再植（autogenic hand replantation，以下统称为“手部修复”（hand restoration））的既往截肢患者，为研究神经系统（尤其是初级躯体感觉皮层（primary somatosensory cortex, S1））在去传入（deafferentation）后的大范围神经可塑性变化提供了独特的研究契机。然而此类患者数量稀缺，既往研究多将单个病例与少量健康成年人对照组进行对比。本研究纳入5名受试者（共完成8次测试：1例移植患者完成2次测试、1例移植患者完成3次测试，3例再植患者各完成1次测试）。我们采用功能磁共振成像（functional magnetic resonance imaging, fMRI），检测受试者左右手指尖及下部面部接受可控气压式触觉刺激（pneumatic tactile stimulation）时的初级躯体感觉皮层响应，并将上述数据与29名健康成年人以及19名当前单侧截肢患者（unilateral amputees）的响应数据进行对比。在对患侧手进行刺激时，患者的患侧初级躯体感觉皮层（即与患手对侧的皮层）的响应模式与截肢患者及健康成年人均较为相似。对侧响应的存在表明其初级躯体感觉皮层功能大体正常，但响应幅度普遍处于健康人群变异范围的下限。患者的患侧初级躯体感觉皮层在接受健侧手刺激时的响应存在显著个体差异：尽管所有患者的响应均落在健康成年人的变异范围内，但部分测试（8次中的4次）出现了与当前截肢患者类似的显著同侧响应（ipsilateral responses）。与手部修复患者不同，当前截肢患者与健康成年人相比表现出显著的初级躯体感觉皮层重组，包括健侧手刺激引发双侧初级躯体感觉皮层响应。我们对三组受试者均开展了触觉定位测试：通过测量受试者识别手掌及手指触觉刺激位置的能力进行评估。值得注意的是，尽管移植患者的触觉定位能力随时间有所提升，但这一变化与初级躯体感觉皮层对触觉刺激的响应变化并无关联。总体而言，本研究首次描述了手部修复术后接受严格可控触觉刺激时的皮层响应特征。本病例系列研究表明，手部修复患者的初级躯体感觉皮层功能处于健康成年人与截肢患者的范围之内，但其响应幅度较低且存在个体特异性，这提示去传入与再传入（re-afferentation）术后可能存在范围广泛的皮层神经可塑性变化。