Age-related hearing loss and behavioral measures of hearing sensitivity in adult zebrafish (Danio rerio)

Abstract

Many teleost fish species have been used in hearing studies to investigate the ontogenetic changes of auditory structures and functions. Zebrafish (Danio rerio), a freshwater species with special hearing adaptations, has become increasingly popular in hearing research studies due to its genetic tractability and ease for maintenance. One of the most studied aspects of zebrafish hearing is how the zebrafish auditory system changes during different developmental stages. In Chapter 1, I describe the development of major auditory structures in zebrafish during early development. I then discuss and update on our current understanding of how measures of zebrafish auditory functions can be used to reveal different levels of activation in the auditory pathway. Finally, I propose future questions that can be asked to improve our understanding about the life-stage dependent changes of the vertebrate auditory system. In Chapter 2, I present evidence for age-related hearing loss in adult zebrafish and discuss the possible mechanisms behind the loss of auditory sensitivity in zebrafish due to age. In Chapter 3, I describe the procedures to test the hearing sensitivity in adult zebrafish using the prepulse inhibition technique. I then discuss possible improvements to this procedure for other researchers interested in following and improving this protocol. In Chapter 4, I demonstrate the differences in the innate acoustic startle response probability and long-term habituation of the startle reflex in three zebrafish strains. In Chapter 5, I discuss the implications of findings in this dissertation and future directions to study auditory sensitivity and behaviors in adult zebrafish.