辐鳍鱼脑的发生、分化及生理功能研究综述

Reviews of the Advances in the Phylogenetic Development,Differentiation and Physiological Function of Ray-Finned Fish Brains

辐鳍鱼类是脊椎动物中最大的类群,其形态、种类和生活习性均表现出极高的多样性。脑是鱼体内重要的神经内分泌中枢、感觉神经中枢和运动中枢,调控着鱼类各项复杂的生理功能和行为,研究鱼脑的结构分区可为鱼脑的功能区域化研究提供理论依据。辐鳍鱼脑沿袭了脊椎动物保守的发育模式:脑起源于神经管前端的3个突起,即前脑、中脑、后脑,进而分化为各脑区。在此过程中,神经管内不同的信号中心表达特定的形态因子诱导了脑区的定向分化,这些因子可作为鉴定脑区的重要分子学证据。但辐鳍鱼脑并非是四足动物脑的简单版本,在与四足动物祖先进化分离后数亿年的过程中,辐鳍鱼脑既保留了保守的发生方式和神经连接,也衍化出了独特的形态构造和多样化的生理功能。目前,辐鳍鱼类端脑和间脑脑区的同源性仍存争议,筛选和定位脑区标志性的形态因子仍然是研究辐鳍鱼脑分区的主要手段。在此基础之上,未来还需要进一步丰富研究的技术手段,从多领域、多角度深化辐鳍鱼脑的研究,探索脑区结构与生理功能之间的联系。

Ray-finned fish species,the largest group of vertebrates,exhibit a tremendous diversity in shape,species and ways of life.The brains of ray-fined fish species are the nerve center of neuroendocrine,somatic sensation and motor coordination,which regulate kinds of complex physiological functions and behaviors.The study of brain regions can provide a theoretical basis for function division.Brains of ray-finned fish species are built according to the conservative developmental pattern of the vertebrate brains.The brain originates from three swellings at the front end of the neural tube,which eventually develops into the prosencephalon,mesencephalon and rhombencephalon,respectively.Finally,they divide into all brain regions.In this process,different signaling centers of the neural tube express specific morphogens,inducing the orientated differentiation of brain regions.These morphogens can be used as a significant molecular evidence of brain region identification.However,the brain of ray-finned fish is not just a simple version of that of mammal.Though the brains of ray-finned fish species follow the conservative patterns of organization and neural connections.Their brains contain some unique morphology structures and diversified physiological functions after they split from primitive tetrapods.The homology of telencephalon and diencephalon of ray-finned fish is still debatable so far,and it is still a main method to sift and identify specific transcription factors of brain regions.On this basis,more techniques will be required for further studies of brain of ray-finned fish in various areas and multiple perspectives to explore the correlation between brain region structures and physiological functions.