When visual and proprioceptive estimates of hand position disagree (e.g., viewing the hand underwater), the brain realigns them to reduce mismatch. This perceptual change is reflected in primary motor cortex (M1) excitability, suggesting potential relevance for hand movement. Here, we asked whether fingertip visuo-proprioceptive misalignment affects only the brain’s representation of that finger (somatotopically focal), or extends to other parts of the limb that would be needed to move the misaligned finger (somatotopically broad). In Experiments 1 and 2, before and after misaligned or veridical visuo-proprioceptive training at the index finger, we used transcranial magnetic stimulation to assess M1 representation of five hand and arm muscles. The index finger representation showed an association between M1 excitability and visuo-proprioceptive realignment, as did the pinkie finger representation to a lesser extent. Forearm flexors, forearm extensors, and biceps did not show any such relationship. In Experiment 3, participants indicated their proprioceptive estimate of the fingertip, knuckle, wrist, and elbow, before and after misalignment at the fingertip. Proprioceptive realignment at the knuckle, but not the wrist or elbow, was correlated with realignment at the fingertip. These results suggest the effects of visuo-proprioceptive mismatch are somatotopically focal in both sensory and motor domains.

中文翻译：

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与视觉本体感觉重新排列相关的知觉和神经生理学变化的体细胞特异性

当手位置的视觉和本体感觉估计不一致时（例如，在水下观察手），大脑会重新调整它们以减少不匹配。这种感知变化反映在初级运动皮层 (M1) 的兴奋性上，表明与手部运动的潜在相关性。在这里，我们询问指尖视觉本体感受错位是否仅影响大脑对该手指的表示（躯体局灶性），或延伸到移动错位手指所需的肢体其他部位（躯体学上宽）。在实验 1 和 2 中，在食指未对齐或真实的视觉本体感受训练之前和之后，我们使用经颅磁刺激来评估五个手和手臂肌肉的 M1 表示。食指表示显示了 M1 兴奋性和视觉本体感觉重新排列之间的关联，小指表示在较小程度上也是如此。前臂屈肌、前臂伸肌和二头肌没有表现出任何这种关系。在实验 3 中，参与者表明他们在指尖错位前后对指尖、指关节、手腕和肘部的本体感受估计。指关节的本体感觉调整与指尖的调整相关，但与手腕或肘部无关。这些结果表明视觉本体感受失配的影响在感觉和运动领域都是躯体局部焦点。参与者表示他们在指尖错位前后对指尖、指关节、手腕和肘部的本体感受估计。指关节的本体感觉调整与指尖的调整相关，但与手腕或肘部无关。这些结果表明视觉本体感受失配的影响在感觉和运动领域都是躯体局部焦点。参与者表示他们在指尖错位前后对指尖、指关节、手腕和肘部的本体感受估计。指关节的本体感觉调整与指尖的调整相关，但与手腕或肘部无关。这些结果表明视觉本体感受失配的影响在感觉和运动领域都是躯体局部焦点。