Many people hear ringing in the ears, known as tinnitus, and researchers now think it could involve abnormally linked brain waves that extend across a large part of the brain.

William Sedley at Newcastle University, UK, Phillip Gander at the University of Iowa in Iowa City and their team recorded brain activity in an awake 50-year-old man with tinnitus, who had electrodes implanted to study his epilepsy.

The researchers used sounds to temporarily suppress the loudness of the tinnitus, and looked for shifts in brain-wave patterns as the tinnitus intensity changed. They found that low-frequency brain waves previously linked to tinnitus spread throughout a larger proportion of the auditory cortex than was thought. Mid- and high-frequency oscillations affected brain regions involved in auditory memory and perception.

The three sets of brain waves seem to interact to create a widespread system of abnormal activity.

Curr. Biol. http://doi.org/338 (2015)