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

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

Department dc:contributor.department

Harvard University--MIT Division of Health Sciences and Technology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Buran, Bradley N. (Bradley Nicholas)

Advisor dc:contributor.advisor

• M. Charles Liberman.

• Harvard University--MIT Division of Health Sciences and Technology.

Statement 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.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/54454

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/54454