Emanuel Stav, Kaiser Maayan, Pflueger Hans-Joachim, Libersat Frederic
Department of Life Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beersheba, Israel.
Fachbereich Biologie Chemie Pharmazie, Institut für Biologie, Neurobiologie, Freie Universität Berlin, Berlin, Germany.
Front Physiol. 2020 Feb 21;11:135. doi: 10.3389/fphys.2020.00135. eCollection 2020.
In insects, locomotion is the result of rhythm generating thoracic circuits and their modulation by sensory reflexes and by inputs from the two head ganglia, the cerebral and the gnathal ganglia (GNG), which act as higher order neuronal centers playing different functions in the initiation, goal-direction, and maintenance of movement. Current knowledge on the various roles of major neuropiles of the cerebral ganglia (CRG), such as mushroom bodies (MB) and the central complex (CX), in particular, are discussed as well as the role of the GNG. Thoracic and head ganglia circuitries are connected by ascending and descending neurons. While less is known about the ascending neurons, recent studies in large insects and have begun to unravel the identity of descending neurons and their appropriate roles in posture and locomotion. Descending inputs from the head ganglia are most important in initiating and modulating thoracic central pattern generating circuitries to achieve goal directed locomotion. In addition, the review will also deal with some known monoaminergic descending neurons which affect the motor circuits involved in posture and locomotion. In conclusion, we will present a few issues that have, until today, been little explored. For example, how and which descending neurons are selected to engage a specific motor behavior and how feedback from thoracic circuitry modulate the head ganglia circuitries. The review will discuss results from large insects, mainly locusts, crickets, and stick insects but will mostly focus on cockroaches and the fruit fly, .
在昆虫中，运动是由产生节律的胸部神经回路以及感觉反射和来自两个头部神经节（即脑和咽下神经节（GNG））的输入对其进行调节的结果，这两个头部神经节作为高阶神经中枢，在运动的起始、目标导向和维持中发挥着不同的功能。本文讨论了目前关于脑神经节（CRG）主要神经纤维网（如蘑菇体（MB）和中央复合体（CX））的各种作用的知识，以及咽下神经节的作用。胸部和头部神经节回路通过上行和下行神经元相连。虽然对上行神经元的了解较少，但最近对大型昆虫的研究已经开始揭示下行神经元的身份及其在姿势和运动中的适当作用。头部神经节的下行输入在启动和调节胸部中央模式产生回路以实现目标导向运动方面最为重要。此外，本文还将讨论一些已知的影响参与姿势和运动的运动回路的单胺能下行神经元。总之，我们将提出一些迄今为止很少被探索的问题。例如，如何以及选择哪些下行神经元来参与特定的运动行为，以及胸部回路的反馈如何调节头部神经节回路。本文将讨论来自大型昆虫（主要是蝗虫、蟋蟀和竹节虫）的研究结果，但将主要关注蟑螂和果蝇。
