Le Feuvre Y, Fénelon V S, Meyrand P
Laboratoire de Neurobiologie des Réseaux, CNRS et Université Bordeaux I, UMR 5816, Talence, France.
Nature. 1999 Dec 9;402(6762):660-4. doi: 10.1038/45238.
It is usually assumed that, after construction of basic network architecture in embryos, immature networks undergo progressive maturation to acquire their adult properties. We examine this assumption in the context of the lobster stomatogastric nervous system. In the lobster, the neuronal population that will form this system is at first orgnanized into a single embryonic network that generates a single rhythmic pattern. The system then splits into different functional adult networks controlled by central descending systems; these adult networks produce multiple motor programmes, distinctively different from the single output of the embryonic network. We show here that the single embryonic network can produce multiple adult-like programmes. This occurs after the embryonic network is silenced by removal of central inputs, then pharmacologically stimulated to restore rhythmicity. Furthermore, restoration of the flow of descending information reversed the adult-like pattern to an embryonic pattern. This indicates that the embryonic network possesses the ability to express adult-like network characteristics, but descending information prevents it from doing so. Functional adult networks may therefore not necessarily be derived from progressive ontogenetic changes in networks themselves, but may result from maturation of descending systems that unmask preexisting adult networks in an embryonic system.
通常认为，在胚胎中构建基本网络架构后，未成熟的网络会经历逐步成熟以获得其成年期特性。我们在龙虾口胃神经系统的背景下研究这一假设。在龙虾中，将形成该系统的神经元群体最初被组织成一个单一的胚胎网络，该网络产生单一的节律模式。然后，该系统分裂为由中央下行系统控制的不同功能的成年网络；这些成年网络产生多种运动程序，与胚胎网络的单一输出明显不同。我们在此表明，单一的胚胎网络可以产生多种类似成年期的程序。这发生在通过去除中央输入使胚胎网络沉默后，然后通过药理学刺激恢复节律性。此外，下行信息流的恢复将类似成年期的模式逆转回胚胎模式。这表明胚胎网络具有表达类似成年期网络特征的能力，但下行信息阻止其这样做。因此，功能性成年网络不一定源自网络自身的逐步个体发育变化，而可能是由于下行系统的成熟，这些下行系统揭示了胚胎系统中预先存在的成年网络。
