People with tinnitus “hear” ringing, buzzing, or hissing in their ears much like an amputee might “feel” pain in a missing limb. While exposure to loud noise may contribute, some cases have no apparent trigger.
Though it’s not known yet exactly where and how tinnitus occurs in the brain, says Richard Salvi, director of the Center for Hearing and Deafness at the University at Buffalo, functional MRI studies with rats show the abnormal activity underlying tinnitus and a related condition called hyperacusis isn’t confined to a specific brain location, but actually involves a neural network.
Salvi and colleagues induced tinnitus in rats by administering the active ingredient in aspirin, which has long been known to produce tinnitus and hyperacusis symptoms in humans.
“Certain brain regions become very active once tinnitus is induced, much more so than it is for an animal with normal hearing,” says Salvi, one of the authors of the study published in the journal eLife. “Even though high-dose aspirin induces a hearing loss and less information is being sent from the ear to the brain as a result, the brain responds with greater activity.
“It’s paradoxical, like a car getting better gas mileage with a less efficient engine.”
