Brain stimulation boosts hearing in rats with ear implants

Stimulating neurons that are linked to alertness helps rats with cochlear implants learn to quickly recognize tunes, researchers have found. The results suggest that activity in a brain region called the locus coeruleus (LC) improves hearing perception in deaf rodents. Researchers say the insights are important for understanding how the brain processes sound, but caution that the approach is a long way from helping people.

Cochlear implants use electrodes in the inner-ear region called the cochlea, which is damaged in people who have severe or total hearing loss. The device converts acoustic sounds into electrical signals that stimulate the auditory nerve, and the brain learns to process these signals to make sense of the auditory world.

Researchers caution that stimulating the LC in humans could be dangerous. The region sends signals to many brain regions, and regulates the fight-or-flight response. Stimulating the LC in people “would raise blood pressure and heart rate, and [induce] other autonomic responses”, says Graeme Clark, an otolaryngologist in the Graeme Clark Institute at the University of Melbourne, Australia, who developed the first multi-channel cochlear implant in the 1970s. “We would have to do a series of experiments to prove that it is something worth doing.”