Neural control of respiration in lampreys

呼吸是一种重要的运动行为，从出生开始，并在整个生命中保持。产生和调节呼吸的神经机制仍然没有得到很好的理解。这样的理解需要关于整个网络的突触连接性以及包括生成器神经元的膜特性的知识。哺乳动物中枢神经系统（CNS）的复杂性使得这项任务变得困难，需要更简单的CNS模型。七鳃鳗是一种基底脊椎动物，大约在5.6亿年前从其他脊椎动物物种中分化出来。然而，它们脑干的组织与哺乳动物惊人地相似。此外，七鳃鳗产生呼吸的神经回路在体外分离其中枢神经系统后保持活跃，并继续产生与在完整动物中观察到的非常相似的呼吸输出。我们建议在系统（突触连接）和细胞（神经元的内在属性）水平上表征七鳃鳗中枢神经系统的神经回路。将建立突触和内在属性对呼吸的相对贡献以及呼吸网络中的连通性。 在许多情况下，呼吸节律被调节。例如，呼吸随着运动而增加。这在传统上被归因于化学感受性反馈。然而，我们最近发现，一个中央前馈机制是参与直接连接之间的运动控制中心在中脑和呼吸发生区在后脑。我们建议，以确定在这个前馈电路中所涉及的细胞机制的细节。总之，从这项研究中获得的信息应该提供可验证的假设，负责产生和调制的哺乳动物，包括人类的呼吸神经组织。

Respiration is a vital motor behaviour that begins at birth and is maintained throughout life. The neural mechanisms generating and modulating respiration are still not well understood. Such an understanding requires knowledge relative to the synaptic connectivity of the entire network as well as the membrane properties of the comprising generator neurons. The complexity of the mammalian Central Nervous System (CNS) renders this task difficult and simpler CNS models are needed. Lampreys are basal vertebrates that have diverged from other vertebrate species some 560 million years ago. The organisation of their brainstem, however, is strikingly similar to that of mammals. Moreover, the neural circuitry generating respiration in lampreys stays active after isolation in vitro of their CNS, and continues to generate respiratory output very similar to that observed in intact animals. We propose to characterize the neural circuitry both at the system (synaptic connectivity) and cellular (intrinsic properties of neurons) levels in the CNS of lampreys. The relative contribution of synaptic and intrinsic properties to respiration will be established as well as the connectivity in the respiratory network. The respiratory rhythm is modulated under many circumstances. For instance, respiration increases in association with movement. This has traditionally been attributed to a chemoreceptive feedback. However, we have recently shown that a central feed-forward mechanism is involved with direct connections between a locomotor control centre in the midbrain and the respiratory generating area in the hindbrain. We propose to identify the details of the cellular mechanisms involved in this feed-forward circuitry. Taken together the information gained from this research should provide testable hypotheses on the neural organization responsible for the generation and modulation of respiration in mammals, including humans.