Here is the full transcript of Josef Rauschecker’s TEDx Talk on Tinnitus: Ringing in the Brain at TEDxCharlottesville conference.
Listen to the MP3 Audio: Tinnitus_ Ringing in the Brain by Josef Rauschecker at TEDxCharlottesville
I would like to talk with you about a medical disorder that is incredibly common, and yet it gets often underestimated – misunderestimated, as one of our former presidents would have said – in its impact on our psychology and on the patients. The patients really suffer from it.
And it’s very pervasive; about 50 million Americans suffer from it. I bet many of you in the audience will have friends or family that suffer from it.
What I’m talking about is tinnitus, the ringing in the ears. It’s often depicted in this painting by Edvard Munch although we don’t know for sure whether he actually had tinnitus himself. But the person in the painting is sort of covering his or her ears, and it doesn’t help because the ringing is actually generated in the brain.
It’s not a real sound that, that a person hears; it’s a phantom sound. So we often talk about it as ringing in the brain rather than ringing in the ears.
And of those 50 million Americans that suffer from it, about 10 million of them really suffer very badly – they go to the extent that they have depression and suicidal thoughts. And I get emails every day from patients that are asking, “Is there not a cure?” There is no cure, unfortunately, at this point. And part of our research is aiming for that, of course, that we’re trying to find ways to help these patients.
And I can play some examples for you, (high-pitched tone) of what that sounds like. This is just a pure tone of a single frequency, relatively rare. Usually, tinnitus sounds more like the next one… (hissing sound). You can imagine how annoying that is. If you hear that all the time in one of your ears or both of your ears. You can’t turn it off, you can’t run away from it; it’s always there.
(cricket sound) Sometimes, you get this more sophisticated cricket sound that you hear. So, people suffer from it. There are groups that are more affected or at risk than others. Musicians get it surprisingly often because they are exposed to louder sounds than they realize. I once remember being at the Kennedy Center in Washington, DC, where we live, and went to a concert there, symphony concert by the National Symphony. They played Shostakovich’s War Symphony. Very loud, of course.
One of the violinists in the first or the second row was sitting right in front of the trombones behind her. The trombone was sort of blowing right into her ear and she was reflexively covering her ears to protect herself.
This is actually the right reaction, just to avoid loud noises in order to avoid getting hair cell damage, and then hearing loss, and ultimately tinnitus.
So, loud noise exposure is certainly one of the biggest risks. And then you take a group like construction workers. If they don’t wear hearing protection, that can be very risky. The group most at risk are our war veterans, of course. They are constantly exposed to artillery fire, to bombs, explosives and so on, you know.
In addition – this is a very important factor, which I want to stress in this presentation – stress is a very important factor. So, it’s not just the loud noise exposure that can give you tinnitus – it actually doesn’t always do that – but if it combines with a stressful situation, this is the most likely scenario where you end up getting tinnitus.
So, our veterans are much more likely to come home from the battlefield with tinnitus. In fact, the Veterans’ Administration, if you look up the statistics, they show that tinnitus is the most frequent cause for benefits paid to veterans. Hearing loss is the second most frequent one.
Tinnitus has often been compared with other phantom sensations like phantom limb pain, which you might have heard about. In this case, somebody misses a limb because of an accident or an explosion that damaged his arm or her leg. And it’s a very similar thing. In this case again, the brain is the cause for this.
Even though the leg may be missing, the neurons in the brain that represent the brain are still there and they are firing along. On occasions, the person might get the impression that his leg is still there. And you can actually feel pain in that leg.
And animal experiments have shown – that’s shown on the right of that slide here – that this is in fact what’s happening. In monkeys that have lost a hand, for example, the hand representation gets filled in with input from the face representation, which is right next to it.
Ramachandra and then neuroscientists in California did studies on amputees, where he showed that if you touch the face of an amputee, they actually feel their phantom hand, in this case, more frequently than not. So, there’s a profound reorganization going on in the brain, both in a phantom limb and in tinnitus, which is the equivalent in the auditory domain.
People have referred to this often as maladaptive plasticity. Plasticity, by definition, should be something good, right? We are learning: this is plasticity; memory is kind of a form of plasticity, so we associate this with an adaptive function. But in this case, is it really adaptive? I would think so. It’s not necessarily maladaptive, because the brain has set out a plan how to deal with these kinds of situations.
So, if you have loud noise exposure, you kill some of your hair cells in the inner ear, and they can’t be replaced; they don’t grow back. So, what the brain does, it kind of fills in that gap. Nature doesn’t like gaps. So, the gap is filled in with neurons that normally respond to other frequencies, like on the left or right of that gap.
Another example is the blind spot in your eye. You all know we have a blind spot in our retina where there are no photoreceptors, so the blood vessels go in and out from there. The optic nerve goes in from there. We don’t see, but we don’t notice that hole because with the same mechanism the brain fills in that hole. And the same thing happens – we call this lesion-induced plasticity. The same thing happens in tinnitus.
So, it is per se an adaptive mechanism. But it has an unintended side effect, this hyperactivity that I’ve been talking about, that we can actually visualize with fMRI, for example.
And then, the next step is missing in tinnitus patients. Normally, the brain is even more clever. It realizes there is this internal noise being generated, so it puts its executive sentence in play and they would suppress that noise. So, most people actually even after extensive loud noise exposure don’t get tinnitus. You might have hearing loss but you don’t end up with tinnitus. You go to a loud noise concert, for example, loud rock concert, and you have tinnitus maybe the next day, but then it goes away after a few days. So, many people have just temporary tinnitus which gets repaired by the brain; there are mechanisms for that.