Noise and aging affect hearing nerve types differently in mice
Experiments comparing five young and seven old mice found that one hearing nerve subtype’s connections were most resilient to age-related loss.
Limit: Only five young and seven old mice in the aging experiments
Edited by Boris Djordjevic · AgingResearch.News
In male and female mice, researchers used genetic labels to study three types of hearing nerve cells and their connections with sound-sensing cells in the inner ear. The animal experiments compared five mice aged 9–11 weeks with seven aged 83–85 weeks. A noise experiment compared seven mice aged 8–9 weeks exposed to 100-decibel noise for two hours with seven unexposed controls.
Type Ia nerve cells had the most resilient connections under both noise exposure and aging. Their signal-receiving structures at these connections were larger than those of types Ib and Ic. These structures increased in volume with age but stayed unchanged after noise exposure. In types Ib and Ic, average volume stayed unchanged with age but decreased after noise. In separate experiments, genetically shifting Ib and Ic cells toward a Ia-like identity reduced noise-induced connection loss.
Why it matters
Loss of connections between sound-sensing cells and hearing nerves is one way the auditory system changes with age. The authors suggest that nerve-cell identity offers an entry point for developing therapies.
Caveats
These were mouse experiments, so the findings do not establish benefits in people. Genetic reprogramming’s reported protection concerned noise-induced connection loss, not age-related loss.
The paper
Harvard University
Nature Communications, Jul 10, 2026, Open access
