神经系统中有多少冗余目前仍是一个没有明确答案的问题。现在，Motojiro Yoshihara及其同事识别出了一对果蝇脑细胞，他们将其称之为Fdg或“进食”神经元，其人工激活足以诱导果蝇完整的进食运动程序。仅仅将这两个神经元抑制或切除就会消除由糖诱导的进食反射，但只将其中一个切除则会导致非对称的运动。这项工作揭示了感觉、代谢和运动系统的耦合中一个严重的瓶颈。（生物谷Bioon.com）
生物谷推荐英文摘要：
Nature doi:10.1038/nature12208
A single pair of interneurons commands the Drosophila feeding motor program
Thomas F. Flood,Shinya Iguchi, Michael Gorczyca,Benjamin White,Kei Ito & Motojiro Yoshihara
Many feeding behaviours are the result of stereotyped, organized sequences of motor patterns. These patterns have been the subject of neuroethological studies, such as electrophysiological characterization of neurons governing prey capture in toads. However, technical limitations have prevented detailed study of the functional role of these neurons, a common problem for vertebrate organisms. Complexities involved in studies of whole-animal behaviour can be resolved in Drosophila, in which remote activation of brain cells by genetic means enables us to examine the nervous system in freely moving animals to identify neurons that govern a specific behaviour, and then to repeatedly target and manipulate these neurons to characterize their function. Here we show neurons that generate the feeding motor program in Drosophila. We carried out an unbiased screen using remote neuronal activation and identified a critical pair of brain cells that induces the entire feeding sequence when activated. These ‘feeding neurons’ (here abbreviated to Fdg neurons for brevity) are also essential for normal feeding as their suppression or ablation eliminates sugar-induced feeding behaviour. Activation of a single Fdg neuron induces asymmetric feeding behaviour and ablation of a single Fdg neuron distorts the sugar-induced feeding behaviour to become asymmetric, indicating the direct role of these neurons in shaping motor-program execution. Furthermore, recording neuronal activity and calcium imaging simultaneously during feeding behaviour reveals that the Fdg neurons respond to food presentation, but only in starved flies. Our results demonstrate that Fdg neurons operate firmly within the sensorimotor watershed, downstream of sensory and metabolic cues and at the top of the feeding motor hierarchy, to execute the decision to feed.
