引用

运动皮层代表肌肉和关节控制，并通过皮质脊髓束(CST)投射到脊髓中间神经元和许多灵长类动物(包括人类)的运动神经元。为了研究这些脊髓CST的解剖机制，我们确定了控制个体前肢关节的运动皮层位点是否有差异地投射到不同的颈脊髓区域，这些区域由区域和经肌肉注射伪狂犬病毒标记的假定末级中间神经元的位置定义。使用皮质内微刺激确定运动皮层关节特异性部位。使用顺行示踪剂确定的来自关节特定部位的CST节段终止场，包括动物之间一致的高密度终止核和周围更可变的低密度投影。来自肩部、肘部和手腕控制部位的核心末端在C5/C6处重叠于内侧背角和中间区，但在C7/C8处分离。肩部部位优先终止于背侧，在背角内;手腕/手指部位，更偏向腹侧的中间区;和肘关节部位，在背角内侧和中间区。伪狂犬病毒注射于肩部、肘部或手腕肌肉，标记了重叠的主要肌肉特异性的假定的前运动中间神经元种群，存活时间为肌肉的断突触转移。在C5/C6，来自所有关节区的CST核心投射位于密集标记的末阶中间神经元区域的内侧，与注射肌肉无关。 At C7/C8 wrist CST core projections overlapped the densest interneuron territory, which was located in the lateral intermediate zone. In contrast, elbow CST core projections were located medial to the densest interneuron territories, and shoulder CST core projections were located dorsally and only partially overlapped the densest interneuron territory. Our findings show a surprising fractionation of CST terminations in the caudal cervical enlargement that may be organized to engage different spinal premotor circuits for distal and proximal joint control.