Tinnitus connected to multiple areas of the brain, scientists find

Scientists used electrodes planted directly into a patient’s brain to carry out the study

Norman Doidge's first book, The Brain That Changes Itself, sold more than a million copies (Alamy)

A new report has contradicted accepted theory and suggested that tinnitus is caused by multiple areas of the brain and not just the part that perceives sound.

Conventional scientific theory suggests that tinnitus is the brain’s response to damage to the tiny hair cells in the inner ear; however, a new report in the journal Current Biology challenges this thinking.

Phillip Gander of the University of Iowa said of the currently accepted theory: "We think it’s wrong, basically."

The Iowa scientists, led by Gander, studied the brain waves of a 50-year-old man.

The subject gave them permission to study his tinnitus, using electrodes that had been planted directly into his brain to reduce his epileptic seizures(after doctors cut a four-inch hole in his skull to implant said electrodes).

The findings suggest that tinnitus might not stem simply from an isolated defect in the auditory cortex, the part of the brain that perceives sound, but that more of the brain might be involved.

"We found essentially that almost all the hearing parts of the brain are involved," said Gander.

"Including a number of other areas of the brain related to processing emotion and memory and attention," he continued.

The researchers used loud sounds to suppress the man’s tinnitus.

By monitoring the patient’s brain waves while his tinnitus was active or silenced, they could identify the brain waves associated with his tinnitus.

"That’s why our paper is a big deal for scientists," Gander says. "We’re able to say what is specific to the tinnitus itself, as opposed to the distress or lapses of attention they might have because of their tinnitus."

As this is only the first patient studied, Gander stressed that the results should be interpreted accordingly.

Gander’s discovery might explain why the condition is so resistant to treatment.

"Maybe the reason tinnitus is so treatment-resistant," Gander says, "is because it’s involved with so many parts of the brain. So any sort of treatment might not be able to knock out one area of that system. You might have to target all of them, which might be very difficult."