Auditory Screening Project

The fairly common occurrence of hearing-loss in both humans and mice, and the anatomical and functional similarities of their inner ears, attests to the potential of mice as models to study congenital hearing loss. To identify genes causing hearing disorders in mice, a large scale, auditory screening project is being undertaken at The Jackson Laboratory. The major objectives of this screening program are: (1) to identify inbred and mutant strains of mice that exhibit inherited, hearing impairment by three months of age, (2) to localize the responsible genes to particular chromosomes by genetic linkage analysis, and (3) to present this information to the research community in a timely fashion. Hundreds of standard inbred, recombinant inbred, and congenic strains are maintained at The Jackson Lab, as well as hundreds of inbred strains with spontaneous or induced mutations. Our goal each year is to screen five mice from at least 200 mouse strains for auditory-evoked brainstem response (ABR) thresholds.

ABR thresholds in mice are determined using a semi-automated computer system (Intelligent Hearing Systems, Miami, Florida). Subdermal needle electrodes are inserted at the vertex and ventrolaterally to both ears of anesthetized mice. Specific auditory stimuli from 10-100 dB SPL are delivered binaurally through plastic tubes from high frequency transducers. ABR thresholds are obtained, in an acoustic chamber, for clicks and for 8, 16, and 32 kHz pure-tone pips. ABR thresholds of all mice and strains tested are entered in spreadsheet files for storage, easy access, and for the production of periodic progress reports. Click-evoked ABR waveforms, obtained at threshold (T) and at T+10, T+20 and T+30 dB or each mouse, are also stored for future reference. Mice of the CBA/CaJ strain are tested periodically as references for normal hearing, and for monitoring the reliability of the equipment and testing procedures.

Auditory-Evoked Brainstem Response (ABR) Thresholds - More information