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These experiments analyze differences in synaptic development in central auditory pathways between normal hearing (CBA/J) and congenitally deaf (dn/dn) mice, which provide valuable insight into central synaptic plasticity corresponding to human congenital deafness. Immunofluorescent analysis of the developmental expression of the calcium buffering proteins calretinin, calbindin d-28k, and parvalbumin at various postnatal time points was performed to assess the effects of altered neural activity on the level and/or pattern of protein expression within these nuclei. Results indicate that the pattern of calbindin and parvalbumin is unaffected by congenital deafness in dn/dn mice. However, the pattern of calretinin expression in the MNTB during development of dn/dn mice differed significantly from that of CBA/J mice, indicating that calcium buffering may be impaired in these synapses without appropriate afferent stimulation.

Abstract: Glutamate AMPA receptors (AMPARs) are major excitatory receptors in the vertebrate CNS. In many biological systems there are changes in the properties of AMPARs during development that are essential for providing an increase in efficiency of information transfer between neurons and a refinement of motor co-ordination and sensory perception and cognition. It is not surprising that improper development or loss of function of AMPARs can lead to many neurological disorders such as epilepsy and amyotrophic lateral sclerosis. Thus, determining the mechanisms by which AMPARs mature is of particular importance. The objectives of my thesis were to characterize the developmental changes in AMPAR-mediated currents in zebrafish Mauthner cells and to determine the mechanisms underlying any changes. The major findings reported in this thesis are that (1) there are developmental changes in the properties of AMPAR-currents as the Mauthner cell matures; (2) the mechanism underlying these changes is a switch in the composition of AMPA receptor subtypes; and (3) PKC is necessary for the developmental switch in AMPAR subtypes from slow receptors to fast receptors. These findings provide valuable insights into the mechanism underlying the development of AMPARs. In addition, they provide the first instance of a signalling link (PKC) required for the developmental subunit switch and the developmental speeding of AMPAR kinetics.