The brain may play a role in helping the ear regulate its sensitivity to sound and compensate for hearing loss by sending a signal to a structure in the inner ear known as the cochlea, according to a USC study that was just published in the Journal of Neuroscience. The discovery could help researchers develop treatments for tough-to-treat hearing disorders such as hyperacusis and tinnitus. The research team developed a new way to look at activity in the inner ear by adapting an imaging technique called optical coherence tomography (OCT), which is widely used to scan the retina for conditions like glaucoma and macular degeneration. The approach enabled them to capture real-time images of the cochlea in action in mice. The researchers found that in healthy mice, cochlear activity does not change over the short term. But in mice with genetic hearing loss, cochlear function increased, indicating that the brain was enhancing the cochlea’s sensitivity as a response to long-term hearing loss. The findings suggest that the brain can send signals to the remaining hair cells, essentially telling them to turn up the volume.