Diversity in a type of nerve cell transmitting sound signals to the brain explains variations in hearing sensitivity
Our sense of hearing begins with minute deflections of sensory hairs on the inner hair cells of the cochlea, a coiled structure in the inner ear, ultimately causing electrical signals to reach the brain. Cells known as type I spiral ganglion neurons (SGNs) are responsible for signal transmission: pictured in a section of mouse cochlea, SGN cell bodies (in green, bottom right-hand corner) extend long projections, or peripheral processes (in red and yellow) to contact hair cells (top left, also in green), then send signals downstream to the brain through the auditory nerve. Recent research shows that type I SGNs fall into three distinct subtypes, which express different sets of proteins, supporting earlier evidence of variation in SGN sensitivity to sound. As work in mice suggests one specific SGN subtype may be linked to age-related hearing loss, appreciating SGN diversity could be critical to tackling different types of hearing defects.
Written by Emmanuelle Briolat
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