Georgetown neuroscientist searches for the cause of tinnitus

Article posted today on the PBS web site:

dr_transcript_pullout There is no treatment, and little consensus on what causes tinnitus. But Josef Rauschecker, a Georgetown University Medical Center neuroscientist, wants to change that. He has been studying […] to better understand the physiological mechanisms responsible for tinnitus. He believes it is caused by a confluence of events: hearing damage combined with functional changes in the limbic system, the part of the brain responsible for both interpreting sound and regulating emotion.

Here’s how he explains it. All patients with tinnitus have some degree of hearing damage. But most people with hearing loss have a built-in mechanism that prevents them from hearing phantom sounds, an “intrinsic noise cancellation system,” he calls it. Within the brain’s limbic system, he believes, is the switch that turns off the phantom sounds for most people. When that switch is dysfunctional, the result can be tinnitus.

Rauschecker and his team published a study last month in the journal Neuron that showed that patients with tinnitus were more likely to have structural changes in the brain’s prefrontal cortex and hyperactivity in the nucleus accumbens, a region of neurons deep in the brain, known to play a role in pleasure, addiction, aggression and fear.

“The nucleus accumbens is the last station in the processing pathway,” Rauschecker said. “And it signals, ‘this is bad, bad, bad.’ And the ventromedial prefrontal cortex that would normally make it go away is broken.”

For many patients, the tinnitus gets worse at times of high emotion or anxiety. Clinical depression rates are estimated to be more than twice the national average among tinnitus patients.

Read the entire article here.

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