As we presented in the paper , with the evolution procedure accomplished of neurons from the single - celled organisms and multicellular animals that lack nervous system , the evolution course of nervous system could be summarized briefly as : chaos phase , equally nerve net , centrilized network phase and bilateral symmetry , hierarchical organization and cephalization phase 研究表明，从原始的单细胞有机体类似神经动作电位的协调功能逐步进化成神经元开始，神经系统大致经历了混沌阶段、平权网络阶段、中心化网络阶段和双侧对称的层次体系结构等进化阶段。
