“We worked out in animal studies that specific combinations of sound and pulses could either increase or decrease the activity of these [fusiform] cells that activate the rest of the brain,” senior author Susan Shore of the university’s Kresge Hearing Research Institute told me in an email. So their device, via headphones and electrodes placed on the person’s neck and head, sends out bursts of sounds and mild electrical pulses that alternate with one another. This theoretically resets the fusiform cells and decreases how often and severely a person’s tinnitus should happen.
Researchers at the University of Michigan believe they’ve figured out how to short-circuit the complex neurological process that results in tinnitus.
One of the leading theories behind what causes most cases of chronic tinnitus is that it begins with misfiring neurons in the dorsal cochlear nucleus—one of the two regions of the brainstem where auditory information is first processed. These neurons, called fusiform cells, are meant to fire when the brain receives input from the outside world, which is one of the first links in an almost simultaneous chain of events that leads to us correctly “hearing” the sound something makes. In people with tinnitus, this synchrony is thrown off-kilter and the fusiform cells fire whenever they please, leading to people hearing sounds that aren’t there. This initial imbalance can be caused by anything from damaging loud noises to ear infections, it’s thought, and often accompanies hearing loss.
The University of Michigan team, based on research they had done with guinea pigs, created (and patented) a device they think can retrain the brain circuitry involved in causing at least some cases of tinnitus.