- Published on 24 October 2014
Researchers from Urbana-Champaign University, Illinois, have shown that people with tinnitus process emotions differently from those with normal hearing. Using brain imaging (functional MRI), they were able to identify that there are significant differences in how the brains of people with tinnitus and those with normal hearing react when submitted to emotion-inducing sound stimuli (such as a crying child, somebody laughing, etc.).
For their study, the American team used 37 subjects, divided into three different groups: people with hearing loss and tinnitus; people with hearing loss without tinnitus; and people without hearing loss or tinnitus. Each of them listened to a set of 30 unpleasant sounds, 30 pleasant sounds, and 30 emotionally-neutral sounds, and their brains were simultaneously observed with a functional MRI. Results show that activity in certain areas of the brain varies from one group to another. What is most interesting is that for people with tinnitus, the difference in brain activity does not occur at the level of the auditory cortex, but rather in other areas of the brain such as the limbic system, which, among other things, is responsible for processing emotions. This shows that the brains of patients with tinnitus process sound the same way but process emotions differently.
For the authors, this is a mechanism used by the brain to adapt to the tinnitus, thereby testifying to the brain’s plasticity. Activity in the amygdala, a brain region associated with emotional processing, was lower in the tinnitus and hearing-loss patients. The authors argue that this means that a part of the amygdala has been reassigned to new functions, so as not to be in active all the time due to the unpleasant sound produced by the tinnitus. In the future, the team of researchers hopes to determine the exact link between tinnitus and the amygdala, as well as each of the brain areas analysed during these experiments.
Source: JR Carpenter-Thompson et al. Alterations of the emotional processing system may underlie preserved rapid reaction time in tinnitus. Brain Resaearch 2014;1567:28-41