Advanced Search

Precision and reliability of cochlear nerve response in mice lacking functional synaptic ribbons

Research and Teaching Output of the MIT Community

Show simple item record

dc.contributor.advisor M. Charles Liberman. en_US Buran, Bradley N. (Bradley Nicholas) en_US
dc.contributor.other Harvard University--MIT Division of Health Sciences and Technology. en_US 2010-04-28T15:35:00Z 2010-04-28T15:35:00Z 2009 en_US 2009 en_US
dc.description Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, 2009. en_US
dc.description Cataloged from PDF version of thesis. en_US
dc.description Includes bibliographical references (p. 87-99). en_US
dc.description.abstract Synaptic ribbons are electron-dense structures surrounded by vesicles and anchored to the presynaptic membrane of photoreceptors, retinal bipolar cells and hair cells. Ribbon synapses are characterized by sustained exocytosis that is graded with stimulus intensity and can achieve high release rates. Leading hypotheses implicate the ribbon in maintenance of a large readily releasable pool (RRP) of presynaptic vesicles which enables rapid and precisely-timed exocytosis that supports instantaneous discharge rates of well over 1000 spikes per second. To gain insight into the function of this specialized presynaptic molecular machinery, we characterized the response properties of single auditory nerve (AN) fibers in a mouse with targeted deletion of a presynaptic scaffolding gene, bassoon, in which ribbons are no longer anchored to the active zone. Since each mammalian AN fiber usually receives input from a single inner hair cell active zone to which a single ribbon is typically anchored, single-fiber recordings from bassoon mutants and control mice offer a sensitive functional metric of the contribution of individual ribbons to neural function. Response properties of mutant AN fibers were similar, in many respects, to wild-type. Spike intervals remained irregular, thresholds were unaffected, dynamic range was unchanged, spike synchronization to en_US
dc.description.abstract (cont.) stimulus phase was unimpaired, the time course of post-onset adaptation and recovery from adaptation were normal, and the ability to sustain discharge throughout a long-duration stimulus was unaffected. These data indicate that the presynaptic mechanisms which regulate precise timing of exocytosis, graded release rates and sustained neurotransmitter release were not impaired by loss of the ribbon. However, reductions were seen in spontaneous and sound-evoked AN fiber discharge rates, coinciding with an increased variance of first spike timing to stimulus onset. Unlike fibers from wild-type mice, mutants failed to show increased peak rate as stimulus onset became more abrupt. The reduction of peak rates and increased first spike variance likely result from degraded reliability of discharge to stimulus onset via a mechanism such as reduced RRP size. Thus, the ribbon appears to support a large RRP that enables the rapid onset rates necessary for the auditory system to resolve stimulus features key for many perceptual tasks. en_US
dc.description.statementofresponsibility by Bradley N. Buran. en_US
dc.format.extent 99 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri en_US
dc.subject Harvard University--MIT Division of Health Sciences and Technology. en_US
dc.title Precision and reliability of cochlear nerve response in mice lacking functional synaptic ribbons en_US
dc.type Thesis en_US Ph.D. en_US
dc.contributor.department Harvard University--MIT Division of Health Sciences and Technology. en_US
dc.identifier.oclc 551154006 en_US

Files in this item

Name Size Format Description
551154006-MIT.pdf 18.81Mb PDF Full printable version

This item appears in the following Collection(s)

Show simple item record