The Effects of Congenital Deafness on Auditory Nerve Synapses: Type I and Type II Multipolar Cells in the Anteroventral Cochlear Nucleus of Cats

详细信息    查看全文

• 作者：Elizabeth E. Redd ; Hugh B. Cahill ; Tan Pongstaporn and David K. Ryugo
• 刊名：JARO - Journal of the Association for Research in Otolaryngology
• 出版年：2002
• 出版时间：December 2002
• 年：2002
• 卷：3
• 期：4
• 页码：403-417
• 全文大小：654 KB
• 刊物类别：Medicine
• 刊物主题：Medicine & Public Health
  Otorhinolaryngology
  Neurosciences
  Neurobiology
  
• 出版者：Springer New York
• ISSN：1438-7573

文摘

Sensory deprivation has been shown to exert detrimental effects on the structure and function of central sensory systems. Congenital deafness represents an extreme form of auditory deprivation, and in the adult white cat, synapses between auditory nerve endings and resident cells of the anteroventral cochlear nucleus exhibited abnormal structure. Endbulbs of Held were reduced in branching and displayed striking hypertrophy of their postsynaptic densities. So-called modified endbulbs showed no change in branching complexity but did exhibit hypertrophy of their postsynaptic densities. These differential pre- and postsynaptic effects prompted the question of how deafness might affect other primary endings and synapses. Thus, we studied type I and type II multipolar cells that receive bouton endings from auditory nerve fibers. Type I multipolar cells project to the contralateral inferior colliculus and have relatively few axosomatic endings; type II multipolar cells project to the contralateral cochlear nucleus and have many axosomatic endings. Compared with normal-hearing cats, bouton endings of congenitally deaf cats were smaller but there was no difference in synaptic vesicle density or size of postsynaptic densities. These data reveal that different classes of primary endings and second-order neurons exhibit different degrees of synaptic anomalies to deafness.