Which cells in the cochlea transduce sound vibrations into neural signals?

• A. Rods and cones.
• B. Hair cells (inner hair cells and outer hair cells).
• C. Neurons of the vestibular nerve.
• D. Supporting cells in scala media.

Answer: (B)

Sound vibrations are converted to neural signals by hair cells in the cochlea. The organ of Corti houses inner and outer hair cells with bundles of stereocilia on their tops. When the basilar membrane moves, the stereocilia bend, and tip links connect adjacent rows. Bending toward the tallest row opens mechanotransduction channels, allowing potassium from the surrounding endolymph to rush in and depolarize the cell. This depolarization opens voltage-gated calcium channels at the hair cell base, triggering the release of glutamate onto the afferent fibers of the auditory nerve. The resulting neural activity carries the sound information to the brain. Inner hair cells are the primary transducers that send precise neural signals, while outer hair cells mainly provide active amplification and tuning of the cochlear response. Other cell types listed do not convert sound into neural signals in the cochlea.