Response Properties of Single Auditory Nerve Fibers in the Mouse

1 Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary and 2 Department of Otology and Laryngology, Harvard Medical School, Boston; and 3 Program in Speech and Hearing Bioscience and Technology, Division of Health Science and Technology, Harvard/Massachusetts Institute of Technology, Cambridge, Massachusetts Submitted 2 June 2004; accepted in final form 21 September 2004 The availability of transgenic and mutant lines makes the mouse a valuable model for study of the inner ear, and a powerful window into cochlear function can be obtained by recordings from single auditory nerve (AN) fibers. This study provides the first systematic description of spontaneous and sound-evoked discharge properties of AN fibers in mouse, specifically in CBA/CaJ and C57BL/6 strains, both commonly used in auditory research. Response properties of 196 AN fibers from CBA/CaJ and 58 from C57BL/6 were analyzed, including spontaneous rates (SR), tuning curves, rate versus level functions, dynamic range, response adaptation, phase-locking, and the relation between SR and these response properties. The only significant interstrain difference was the elevation of high-frequency thresholds in C57BL/6. In general, mouse AN fibers showed similar responses to other mammals: sharpness of tuning increased with characteristic frequency, which ranged from 2.5 to 70 kHz; SRs ranged from 0 to 120 sp/s, and fibers with low SR (