Getting to the bottom of the phantom sounds of tinnitus

You are looking at ways to help people ‘unlearn’ the phantom sounds of tinnitus, can you explain?

In tinnitus, a person hears phantom sounds such as ringing or hissing even though there is no outside source of that noise. People used to think that tinnitus was an ear problem, but recent evidence suggests the brain is very much involved, and my lab wants to better understand the mechanisms behind it.

We think that the person’s brain starts to expect the phantom noises, and we want to help them unlearn that, so the brain no longer sets the phantom noise as the expected status quo.

Why might someone’s brain make them ‘hear’ a phantom sound?

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In tinnitus, people have often experienced some kind of hearing loss. The brain predicts that a sound will come in, but it doesn’t. This is what we call a prediction error, and in tinnitus we think the brain responds to the mismatch or uncertainty by filling in noise. Then this noise becomes the prediction, tinnitus becomes the new normal.

How can someone unlearn this new normal?

This is where neuromodulation comes in. We stimulate a specific nerve that runs from the back of the head, called the greater occipital nerve. We use a device like an electrode on your head and it doesn’t hurt. Some people say it feels a bit tingly.

We found out if you stimulate that particular nerve it activates a specific brain pathway that improves how we stabilise memories. So we combine this nerve stimulation with training where the person pays attention to sounds that we play. We train them to differentiate between tones that sound very similar.

The idea is that this combination will teach the brain that all noises are important, and to stop filling in blanks with phantom noises. We are currently testing this in the lab.

Can you use the technology to help people with memory or other issues too?

Yes, we have projects on how neuromodulation might be able to help people with mild cognitive impairment or other memory impairments, and also how the unlearning process might be applied to types of chronic pain.

You publish prolifically, do you enjoy the work?

I love research, and I have a large group of PhD students and post-docs working on projects. I encourage them to write papers and help them with that as part of their training. I enjoy the writing process.

What was your route to Ireland?

After my initial training in Belgium, I worked in Harvard for two years as a postdoc, then I moved to the University of Texas to lead a large trial. Through conversations with Prof Ian Robertson, I learned more about the Global Health Brain Institute and I moved to Trinity about four years ago. I still hold a position in Texas and I have many links with colleagues there.

And what do you like to do in your spare time?

I don’t really have any. When I’m not doing the research in Ireland, I work in a clinic that I set up in Belgium with some medical colleagues to apply brain stimulation techniques.

I’m also about to start a big project with partners in the US. We are looking for objective markers of tinnitus, to see are there specific signals in the brain that correlate with how loudly the person hears phantom noises. This could really help to push the field forward and build more interest in tinnitus research and solutions.