Evolution of gustatory reflex systems in the brainstems of fishes  

作　　者：Thomas E.FINGER 

机构地区：[1]Department of Cell and Developmental Biology,University of Colorado Denver,Aurora,USA

出　　处：《Integrative Zoology》2009年第1期53-63,共11页整合动物学（英文版）

摘　　要：The great number of species of teleosts permits highly specialized forms to evolve to occupy particular niches.This diversity allows for extreme variations in brain structure according to particular sensory or motor adaptations.In the case of the taste system,goldfish(Carassius auratus L.,1758)and some carps have evolved a specialized in-traoral food-sorting apparatus along with corresponding specializations of gustatory centers in the brainstem.A comparison of circuitry within the complex vagal lobe of goldfish,and of the simpler gustatory lobes in catfish(Ictalurus punctatus Rafinesque,1818)shows numerous similarities in organization and neurotransmitters.Double labeling studies using horseradish peroxidase and biotinylated dextran amine in catfish shows a direct projection from the vagal lobe to the motoneurons of nucleus ambiguus which innervate oropharyngeal musculature.Therefore,a three neuron reflex arc connects gustatory input to motor output.In the vagal lobe of goldfish,a similar three neuron arc can be identified:from primary gustatory afferent,to vagal lobe interneuron,thence to dendrites of the vagal motoneurons that innervate the pharyngeal muscles.Therefore,despite large differences in the gross appearance of the vagal gustatory systems in the brains of catfish and goldfish,the essential connectivity and circuitry is similar.This suggests that evolutionary change in the central nervous system largely proceeds by rearrangement and elaboration of existing systems,rather than by addition of new structures or circuits.

关 键 词：EVOLUTION MEDULLA nucleus of the solitary tract TASTE vagus nerve. 

分 类 号：Q43[生物学—生理学]