Einzelfaserableitungen aus dem Nervus cochlearis von Bassoon-Mutanten der Maus
Final Report Abstract
During my one-year postdoctoral period at the Eaton-Peabody Laboratory in Boston, I learned to record from and label mouse single auditory nerve fibers and to perform the basic histological and immunohistochemical processing of mouse cochleae. I participated in three projects under the supervision of Prof. M. Charles Liberman. 1. Continuing an ongoing collaboration between the groups of Prof. T. Moser and Prof. M. C. Liberman, I found that depression of auditory brainstem responses in Bassoon knockout mice, which lack functional ribbon synapses, was associated with reduced action potential rates and enhanced forward masking in auditory nerve fibers, whereas the temporal precision of coding was not affected. Thus, the main role of the synaptic ribbon appears to be in providing a sufficient supply of vesicles to the hair cell synapse. 2. In triple-knockout mice for the main three calcium-buffering proteins in inner hair cells: calbindin, calretinin and parvalbumin-alpha, there was only a discrete phenotype in auditory systems physiology: Auditory brainstem responses and otoacoustic emissions were normal, in single auditory nerve fibers there was a slight tendency towards higher action potential rates. This is consistent with the results of patch clamp experiments performed simultaneously by Dr. T. Pangrsic (Göttingen), demonstrating increased exocytosis from inner hair cells from mutant mice. The lack of calcium buffers in mutant mice may be partially compensated by calcium uptake into mitochondria, or the close spatial relationship between calcium channels and calcium sensors may prevent buffer effects. 3. Labeling of single auditory nerve fibers by iontophoresis of biocytin and subsequent histological processing was successfully performed. However, due to time constraints, data quantity is not yet sufficient for the publication of results.
Publications
- Detection and differentiation of sensorineural hearing loss in mice using auditory steady-state responses and transient auditory brainstem responses. Neuroscience, 2007. 149(3): p. 673-84
Pauli-Magnus, D., G. Hoch, N. Strenzke, S. Anderson, T.J. Jentsch, and T. Moser
