Department of Biology II, LMU Munich, Planegg, Germany.
Dev Neurobiol. 2012 Apr;72(4):649-63. doi: 10.1002/dneu.20965.
The amphibian Xenopus laevis represents a highly amenable model system for exploring the ontogeny of central neural networks, the functional establishment of sensory-motor transformations, and the generation of effective motor commands for complex behaviors. Specifically, the ability to employ a range of semi-intact and isolated preparations for in vitro morphophysiological experimentation has provided new insights into the developmental and integrative processes associated with the generation of locomotory behavior during changing life styles. In vitro electrophysiological studies have begun to explore the functional assembly, disassembly and dynamic plasticity of spinal pattern generating circuits as Xenopus undergoes the developmental switch from larval tail-based swimming to adult limb-based locomotion. Major advances have also been made in understanding the developmental onset of multisensory signal processing for reactive gaze and posture stabilizing reflexes during self-motion. Additionally, recent evidence from semi-intact animal and isolated CNS experiments has provided compelling evidence that in Xenopus tadpoles, predictive feed-forward signaling from the spinal locomotor pattern generator are engaged in minimizing visual disturbances during tail-based swimming. This new concept questions the traditional view of retinal image stabilization that in vertebrates has been exclusively attributed to sensory-motor transformations of body/head motion-detecting signals. Moreover, changes in visuomotor demands associated with the developmental transition in propulsive strategy from tail- to limb-based locomotion during metamorphosis presumably necessitates corresponding adaptive alterations in the intrinsic spinoextraocular coupling mechanism. Consequently, Xenopus provides a unique opportunity to address basic questions on the developmental dynamics of neural network assembly and sensory-motor computations for vertebrate motor behavior in general.
非洲爪蟾（Xenopus laevis）是一种非常适合的模式生物系统，可用于探索中枢神经网络的个体发生、感觉-运动转换的功能建立以及复杂行为的有效运动指令的产生。具体来说，使用一系列半整体和分离的制备物进行体外形态生理学实验的能力，为与在不断变化的生活方式中产生运动行为相关的发育和整合过程提供了新的见解。体外电生理学研究已经开始探索脊髓模式生成电路的功能组装、拆卸和动态可塑性，因为非洲爪蟾经历了从幼虫尾部游泳到成年肢部运动的发育转变。在自我运动期间，对反应性眼球和姿势稳定反射的多感觉信号处理的发育起始也取得了重大进展。此外，来自半整体动物和分离中枢神经系统实验的最新证据提供了令人信服的证据，表明在非洲爪蟾蝌蚪中，来自脊髓运动模式发生器的预测性前馈信号参与了在尾部游泳期间最小化视觉干扰。这个新概念质疑了传统的视网膜图像稳定观点，即在脊椎动物中，视网膜图像稳定完全归因于身体/头部运动检测信号的感觉-运动转换。此外，与从尾部到肢部运动的推进策略发育转变相关的视觉运动需求的变化，推测需要对固有脊椎眼外耦合机制进行相应的适应性改变。因此，非洲爪蟾为解决有关脊椎动物运动行为的神经网络组装和感觉-运动计算的发育动态的基本问题提供了独特的机会。
