How does a mouse hear? - briefly
Mice detect sound with a highly sensitive cochlea that transforms acoustic vibrations into neural impulses, aided by ear canals and a tympanic membrane tuned to frequencies up to 100 kHz. The impulses travel along the auditory nerve to brain centers that decode ultrasonic cues for navigation and communication.
How does a mouse hear? - in detail
Mice detect acoustic signals through a highly specialized auditory system that begins with the external ear and ends in the central auditory pathways. Sound waves enter the ear canal, causing the tympanic membrane to vibrate. These vibrations are transmitted via the ossicular chain—malleus, incus, and stapes—to the oval window of the cochlea.
Inside the cochlea, the basilar membrane separates fluid compartments of differing density. Varying frequencies cause specific regions of the membrane to move, a process known as tonotopic organization. High‑frequency sounds peak near the base, while low‑frequency sounds peak toward the apex. The mechanical motion deflects stereocilia on inner hair cells, converting mechanical energy into electrochemical signals through mechanoelectrical transduction channels.
Key elements of the peripheral auditory apparatus:
- Outer hair cells: amplify and sharpen frequency selectivity via electromotility.
- Inner hair cells: primary transducers, releasing glutamate onto afferent fibers.
- Auditory nerve fibers: convey graded spike trains to the cochlear nucleus.
- Cochlear nuclei: perform initial signal processing, including timing and intensity discrimination.
From the cochlear nucleus, auditory information follows three major pathways:
- Ascending lateral lemniscal tract: projects to the inferior colliculus, preserving temporal precision for sound localization.
- Medial geniculate body: relays signals to the auditory cortex, where complex patterns are interpreted.
- Descending corticofugal system: modulates cochlear gain and sensitivity based on behavioral context.
Mice possess an auditory range roughly from 1 kHz to 100 kHz, with peak sensitivity near 15–20 kHz. This high-frequency capability aligns with their reliance on ultrasonic vocalizations for social communication and predator avoidance. The auditory brainstem circuitry includes specialized nuclei—such as the superior olivary complex—that compute interaural time and intensity differences, enabling precise spatial hearing.
Overall, the mouse auditory system integrates mechanical filtering, cellular transduction, neural encoding, and central processing to transform airborne vibrations into perceptual representations of the acoustic environment.