Carmona Lina Marcela, Thomas E T, Smith Kimberly, Tasic Bosiljka, Costa Rui M, Nelson Anders
bioRxiv. 2023 Nov 17:2023.11.17.567623. doi: 10.1101/2023.11.17.567623.
Corticospinal neurons (CSNs) synapse directly on spinal neurons, a diverse group of neurons with unique structural and functional properties necessary for body movements. CSNs modulating forelimb behavior fractionate into caudal forelimb area (CFA) and rostral forelimb area (RFA) motor cortical populations. Despite their prominence, no studies have mapped the diversity of spinal cell types targeted by CSNs, let alone compare CFA and RFA populations. Here we use anatomical and RNA-sequencing methods to show that CSNs synapse onto a remarkably selective group of spinal cell types, favoring inhibitory populations that regulate motoneuron activity and gate sensory feedback. CFA and RFA CSNs target similar spinal cell types, with notable exceptions that suggest these populations differ in how they influence behavior. Finally, axon collaterals of CFA and RFA CSNs target similar brain regions yet receive surprisingly divergent inputs. These results detail the rules of CSN connectivity throughout the brain and spinal cord for two regions critical for forelimb behavior.
皮质脊髓神经元（CSNs）直接与脊髓神经元形成突触，脊髓神经元是一组多样化的神经元，具有身体运动所需的独特结构和功能特性。调节前肢行为的CSNs可分为尾侧前肢区（CFA）和 Rostral前肢区（RFA）运动皮质群体。尽管它们很突出，但尚无研究绘制出CSNs靶向的脊髓细胞类型的多样性，更不用说比较CFA和RFA群体了。在这里，我们使用解剖学和RNA测序方法表明，CSNs与一组非常有选择性的脊髓细胞类型形成突触，倾向于调节运动神经元活动和控制感觉反馈的抑制性群体。CFA和RFA CSNs靶向相似的脊髓细胞类型，但有明显例外，这表明这些群体在影响行为的方式上存在差异。最后，CFA和RFA CSNs的轴突侧支靶向相似的脑区，但接收到惊人不同的输入。这些结果详细说明了CSN在整个大脑和脊髓中连接的规则，这两个区域对前肢行为至关重要。
