In search of tinnitus, that phantom ringing in the ears

April 23, 2015
In search of tinnitus, that phantom ringing in the ears
A 3-D image of the left brain hemisphere of a patient with tinnitus (right) and the part of that hemisphere containing primary auditory cortex (left). Black dots indicate all the sites recorded from. Colored circles indicate electrodes at which the strength of ongoing brain activity correlated with the current strength of tinnitus perceived by the patient. Different colors indicate different frequencies of brain activity (blue = low, magenta = middle, orange = high) whose strength changed alongside tinnitus. Green squares indicate sites where the interaction between these different frequencies changed alongside changes in tinnitus. Credit: Sedley, W et al.

About one in five people experience tinnitus, the perception of a sound—often described as ringing—that isn't really there. Now, researchers reporting in the Cell Press journal Current Biology on April 23 have taken advantage of a rare opportunity to record directly from the brain of a person with tinnitus in order to find the brain networks responsible.

The observations reveal just how different tinnitus is from normal representations of sounds in the .

"Perhaps the most remarkable finding was that activity directly linked to tinnitus was very extensive, and spanned a large proportion of the part of the brain we measured from," says Will Sedley of Newcastle University. "In contrast, the brain responses to a sound we played that mimicked [the subject's] tinnitus were localized to just a tiny area."

In the new study, Sedley and The University of Iowa's Phillip Gander contrasted during periods when tinnitus was relatively stronger and weaker. The study was only possible because the 50-year-old man they studied required invasive electrode monitoring for epilepsy. He also happened to have a typical pattern of tinnitus, including ringing in both ears, in association with hearing loss.

"It is such a rarity that a person requiring invasive electrode monitoring for epilepsy also has tinnitus that we aim to study every such person if they are willing," Gander says.

The researchers found the expected tinnitus-linked brain activity, but they report that the unusual activity extended far beyond circumscribed auditory cortical regions to encompass almost all of the auditory cortex, along with other parts of the brain.

The discovery adds to the understanding of tinnitus and helps to explain why treatment has proven to be such a challenge, the researchers say.

"We now know that tinnitus is represented very differently in the brain to normal sounds, even ones that sound the same, and therefore these cannot necessarily be used as the basis for understanding tinnitus or targeting treatment," Sedley says.

"The sheer amount of the brain across which the tinnitus network is present suggests that tinnitus may not simply 'fill in' the 'gap' left by hearing damage, but also actively infiltrates beyond this into wider brain systems," Gander adds.

These new insights may help to inform treatments such as neurofeedback, where patients learn to control their "brainwaves," or electromagnetic brain stimulation, according to the researchers. A better understanding of the brain patterns associated with may also help point toward new pharmacological approaches to treatment, "which have so far generally been disappointing."

Explore further: People with tinnitus process emotions differently from their peers, researchers report

More information: Current Biology, Sedley et al.: "Intracranial mapping of a cortical tinnitus system using residual inhibition" dx.doi.org/10.1016/j.cub.2015.02.075

Related Stories

AAO-HNSF clinical practice guideline: Tinnitus

October 1, 2014

The American Academy of Otolaryngology—Head and Neck Surgery Foundation has released the first ever mutli-disciplinary, evidence-based clinical practice guideline to improve the diagnosis and management of tinnitus, the ...

Range of cures likely for tinnitus

March 27, 2014

(Medical Xpress)—Tinnitus researchers agree that there may never be a single cure for tinnitus, but instead a range of treatments for different types of tinnitus will be needed.

Recommended for you

Study finds gray matter density increases during adolescence

May 26, 2017

For years, the common narrative in human developmental neuroimaging has been that gray matter in the brain - the tissue found in regions of the brain responsible for muscle control, sensory perception such as seeing and hearing, ...

Researchers identify brain network organization changes

May 25, 2017

As children age into adolescence and on into young adulthood, they show dramatic improvements in their ability to control impulses, stay organized, and make decisions. Those executive functions of the brain are key factors ...

Scientists demonstrate the existence of 'social neurons'

May 25, 2017

The existence of new "social" neurons has just been demonstrated by scientists from the Institut de neurosciences des systèmes (Aix-Marseille University / INSERM), the Laboratoire de psychologie sociale et cognitive (Université ...

How fear can develop out of others' traumas

May 25, 2017

What happens in the brain when we see other people experiencing a trauma or being subjected to pain? Well, the same regions that are involved when we feel pain ourselves are also activated when we observe other people who ...

Babies' slow brain waves could predict problems

May 25, 2017

The brain waves of healthy newborns – which appear more abnormal than those of severe stroke victims – could be used to accurately predict which babies will have neurodevelopmental disorders.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.