The “phantom sounds” of a hearing condition called tinnitus can leave people exasperated at constantly hearing nonexistent noises like ringing, buzzing, chirping, or hissing. A new study finds that the constant ringing in the ears of tinnitus patients may not only affect hearing, but may also have an impact on how emotions are processed.
The research out of the University of Illinois, and published in the journal Brain Research, found that people with tinnitus process emotions differently than people who don’t have the condition. For the study, researchers used fMRI scans (functional magnetic resonance imaging) in order to examine the brains of participants while they listened to pleasant, unpleasant, and neutral sounds. The participants either had hearing loss, tinnitus, or completely normal hearing, and researchers compared and contrasted these three groups.
Tinnitus and hearing loss patients showed less activity in their amygdalas, the part of the brain that’s linked to emotions, than people with normal hearing. However, tinnitus patients had more activity in two other brain regions often associated with emotion, the parahippocampus and the insula. “The amygdala isn’t the only player,” Fatima Husain, an author of the study and a professor at the University of Illinois at Urbana-Champaign, told LiveScience.
But why does the distribution of activity in the brain’s emotional regions vary so much in tinnitus patients compared to people with regular hearing? Husain believes that tinnitus patients — who hear phantom sounds like whooshing noises, train whistles, and cricket chirps — have adjusted brains that process both phantom sounds and regular sounds, redistributing them among different areas of the brain.
“Our results suggest that the emotional processing network is altered in tinnitus to rely on the parahippocampus and insula, rather than the amygdala, and this alteration may maintain a select advantage for the rapid processing of affective stimuli despite the hearing loss,” the authors of the study wrote. “The complex interaction of tinnitus and the limbic system should be accounted for in development of new tinnitus management strategies.”
Currently, most tinnitus patients are able to live with their condition and still function normally. But about 20 percent of the 50 million Americans who have tinnitus have a severe form of it that makes it difficult for them to sleep, which can cause depression and anxiety. There is no cure for the condition, but “[t]here are therapies to manage it,” Husain said. “But the sound itself won’t disappear.” She hopes her research will help shed more light on the condition and support future therapies that might make life easier for tinnitus patients.
Source: Scmidt S, Akrofi K, Carpenter-Thompson J, Dolcos F, Husain F. Alterations of the emotional processing system may underlie preserved rapid reaction time in tinnitus. Brain Research, 2014.