鱼儿时而摆动尾鳍，时而水中静立，这是“哪根神经”指挥着呢？日本研究人员最近找到了鱼儿游走的奥秘。
小型热带鱼斑马鱼是研究人员研究鱼类的常用对象。日本自然科学研究机构生理学研究所的一个研究小组发现，斑马鱼的后脑部分存在著名为“V2a”的神经细胞群，研究人员通过基因操作，将能与蓝光发生反应的蛋白质植入其中，照射蓝光之后细胞就开始“兴奋”，斑马鱼就左右晃动尾巴游动。
研究人员又拿另外一种蛋白质进行测试，这种蛋白质被植入“V2a”神经细胞群后，受到绿光照射会抑制细胞发挥作用。在斑马鱼游动时向其后脑部位照射绿光，它就神奇地停止了游动。
研究小组由此认为，“V2a”神经细胞群负责操控脊椎的运动系统神经回路，这一机制很可能适用于其他脊椎动物。相关研究成果已刊登在新一期《当代生物学》杂志网络版上。（生物谷Bioon.com）
doi:10.1016/j.cub.2013.03.066
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Hindbrain V2a Neurons in the Excitation of Spinal Locomotor Circuits during Zebrafish Swimming
Yukiko Kimura， Chie Satou， Shunji Fujioka， Wataru Shoji， Keiko Umeda， Toru Ishizuka， Hiromu Yawo， Shin-ichi HigashijimaSee Affiliations
During locomotion in vertebrates， reticulospinal neurons in the hindbrain play critical roles in providing descending excitation to the spinal cord locomotor systems. However， despite the fact that many genes that are used to classify the neuronal identities of neurons in the hindbrain have been identified， the molecular identity of the reticulospinal neurons that are critically involved in locomotor drive is not well understood. Chx10-expressing neurons (V2a neurons) are ipsilaterally projecting glutamatergic neurons in the spinal cord and the hindbrain. Many of the V2a neurons in the hindbrain are known to project to the spinal cord in zebrafish， making hindbrain V2a neurons a prime candidate in descending locomotor drive.ResultsWe investigated the roles of hindbrain V2a neurons using optogenetic and electrophysiological approaches. The forced activation of hindbrain V2a neurons using channelrhodopsin efficiently evoked swimming， whereas the forced inactivation of them using Archearhodopsin3 or Halorhodpsin reliably stopped ongoing swimming. Electrophysiological recordings of two populations of hindbrain reticulospinal V2a neurons showed that they were active during swimming. One population of neurons， small V2a neurons in the caudal hindbrain， fired with low rhythmicity， whereas the other population of neurons， large reticulospinal V2a neurons， called MiV1 neurons， fired more rhythmically.
