Spinal premotor interneurons controlling antagonistic muscles are spatially intermingled.
Spinal premotor interneurons controlling antagonistic muscles are spatially intermingled.
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DOI：
10.7554/elife.81976
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发表时间：
2022-12-13
期刊：
影响因子：
7.7
通讯作者：
Beato M
中科院分区：
文献类型：
--
作者：
Ronzano R;Skarlatou S;Barriga BK;Bannatyne BA;Bhumbra GS;Foster JD;Moore JD;Lancelin C;Pocratsky AM;Özyurt MG;Smith CC;Todd AJ;Maxwell DJ;Murray AJ;Pfaff SL;Brownstone RM;Zampieri N;Beato M
精细的行为是由严格控制的屈伸肌运动神经元激活模式产生的。运动神经元由脊髓内的中间神经元网络调节，但运动控制所涉及的计算过程尚不完全清楚。运动神经元和前运动神经元按照与其受控肌肉相关的地形模式进行神经解剖学排列，被认为有助于促进脊髓回路处理信息的方式。狂犬病逆行单突触追踪已被用来标记支配特定运动神经元池的运动前中间神经元，之前的研究报告了屈肌和伸肌前运动中间神经元的地形中外侧位置偏差。为了更精确地定义接触特定运动池的运动前中间神经元如何组织，我们在小鼠中使用了多种互补的病毒追踪方法，以尽量减少与每种方法相关的系统偏差。与预期相反，我们发现接触控制踝关节屈曲和伸展的运动池的运动前中间神经元高度混合，而不是像运动神经元那样分离到特定区域。因此，在屈伸肌回路组件之间缺乏清晰的空间模式的情况下，控制不同肌肉的运动前脊髓神经元处理运动指令。脊髓包含控制身体运动的神经细胞回路。在这些网络中，中间神经元投射到运动神经元，运动神经元支配不同类型的肌肉收缩：屈肌（如二头肌），使身体的关节弯曲或“弯曲”；伸肌（如三头肌），导致关节伸展。这些运动信号必须仔细协调，才能精确稳定地控制身体的运动。先前的研究表明，中间神经元在脊髓中的位置取决于它们是否激活负责屈曲或伸展的运动神经元。为了测试这些发现是否可重复，Ronzano、Skarlatou、Barriga、Bannatyne、Bhumbra 等人。研究了使小鼠踝关节弯曲和伸展的中间神经元。研究小组与多个实验室合作，使用多种技术来追踪中间神经元和运动神经元在小鼠脊髓中的连接方式。这表明，无论使用何种方法或进行实验的实验室如何，与屈曲和伸展相关的中间神经元的分布都是相互重叠的。这一发现与之前发表的结果相矛盾，并表明脊髓中的中间神经元并不是根据其输出进行分离的。相反，它们可以根据接收到的信号进行定位，类似于运动神经元。了解中间神经元在脊髓中的位置将为了解运动如何控制以及运动如何受到损伤和疾病的影响提供新的见解。将来，这些知识可能有助于研究脊髓中的神经回路如何形成以及如何再生。
Elaborate behaviours are produced by tightly controlled flexor-extensor motor neuron activation patterns. Motor neurons are regulated by a network of interneurons within the spinal cord, but the computational processes involved in motor control are not fully understood. The neuroanatomical arrangement of motor and premotor neurons into topographic patterns related to their controlled muscles is thought to facilitate how information is processed by spinal circuits. Rabies retrograde monosynaptic tracing has been used to label premotor interneurons innervating specific motor neuron pools, with previous studies reporting topographic mediolateral positional biases in flexor and extensor premotor interneurons. To more precisely define how premotor interneurons contacting specific motor pools are organized, we used multiple complementary viral-tracing approaches in mice to minimize systematic biases associated with each method. Contrary to expectations, we found that premotor interneurons contacting motor pools controlling flexion and extension of the ankle are highly intermingled rather than segregated into specific domains like motor neurons. Thus, premotor spinal neurons controlling different muscles process motor instructions in the absence of clear spatial patterns among the flexor-extensor circuit components. The spinal cord contains circuits of nerve cells that control how the body moves. Within these networks are interneurons that project to motor neurons, which innervate different types of muscle to contract: flexors (such as the biceps), which bend, or ‘flex’, the body’s joints, and extensors (such as the triceps), which lead to joint extension. These motor signals must be carefully coordinated to allow precise and stable control of the body’s movements. Previous studies suggest that where interneurons are placed in the spinal cord depends on whether they activate the motor neurons responsible for flexion or extension. To test if these findings were reproducible, Ronzano, Skarlatou, Barriga, Bannatyne, Bhumbra et al. studied interneurons which flex and extend the ankle joint in mice. In collaboration with several laboratories, the team used a combination of techniques to trace how interneurons and motor neurons were connected in the mouse spinal cord. This revealed that regardless of the method used or the laboratory in which the experiments were performed, the distribution of interneurons associated with flexion and extension overlapped one another. This finding contradicts previously published results and suggests that interneurons in the spinal cord are not segregated based on their outputs. Instead, they may be positioned based on the signals they receive, similar to motor neurons. Understanding where interneurons in the spinal cord are placed will provide new insights on how movement is controlled and how it is impacted by injuries and disease. In the future, this knowledge could benefit work on how neural circuits in the spinal cord are formed and how they can be regenerated.
影响因子：
2.9
作者：
Ohara S;Inoue K;Yamada M;Yamawaki T;Koganezawa N;Tsutsui K;Witter MP;Iijima T
通讯作者：
Iijima T