Going Topless Harms your Hearing

Kat -   Now I am sure that all of us have a certain piece of music that causes chills to run up our spines.  Music so good, it elicits a genuine physical reaction.  Now, researchers at Montreal Neurological Institute and Hospital have been exploring the brain basis of this experience, and to tell us more, we're joined by McGill University's Valorie Salimpoor.  Hi, Valorie.

Valorie -   Hi.  How are you?

Kat -   Great!  Now tell us a little bit about the background to this.  So what were you trying to find out with these experiments?

Valorie -   Well, we know that music has been around for a very long time.  We know that it's been around throughout history and in every single culture.  Evidence for this goes as far back as history has been recorded and we know that things that usually stick around for long periods of time are usually behaviours that are biologically adaptive, or necessary for survival.  But we are still somewhat unclear on how exactly music fits into this.  So, what we do know is that music makes us feel really good and in fact, the euphoric feelings produced by music have often been described as similar to the rush of very powerful drugs like cocaine, for example.  Interestingly, drugs like cocaine actually exert their effects on the dopamine reward circuit in the brain.  And the reason why this is relevant is because the system in the brain is actually a phylogenetically ancient system and it has evolved to reinforce highly adaptive behaviours such as eating and sex for example.  So when dopamine is released, these behaviours are strongly reinforced.

Kat -   So it's kind of the bit of the brain, the pleasure centre of the brain.

Valorie -   Exactly.

Kat -   So how did you test whether this pleasure centre is linked to listening to music?

Valorie -   Well we wanted to see if music is actually linked into the system and this is a hypothesis that's been around for a while.  So, a few researchers have attempted to examine this. People have found, with their colleagues, that when you're listening to pleasurable music, there are some hemodynamic changes in the regions of the brain that are normally involved in dopamine or take reward.  But the problem with that is, up until now, we didn't know if the neurotransmitter dopamine was actually involved.  So we used a procedure called PET.  This is Positron Emission Tomography and this uses radio ligands to determine how much dopamine is actually released and where.  So people came in and they brought in their own self selected music that was intensely pleasurable for them and when they listened to it inside of the scanner, we actually found that they released dopamine.  And this is sort of a big deal because the system is a very potent reinforcer and it actually, by definition, underlies our motivation and our desire to seek a reward.

Kat -   So they're basically getting a natural high from listening to these tunes.

Valorie -   That's exactly it, yes.  Except that there are no severe consequences like there would be with drugs for example.

Kat -   But one question I have.  I mean, music is such a powerful thing in our culture and how do you know that these people don't just, "Oh, I love this piece of Debussy because it was played at my wedding."  How do you separate whether it's just a nice memory or whether it's actually the music?

Valorie -   That's actually an excellent question because music has such tight links with our memory systems that it's really, really hard to separate out the two and music is often used to sort of stimulate these pleasurable memories.  So, the way that we tried to rule that out in our experiment is by doing extensive pilot testing where we asked people, is this in any way associated with a specific episodic memory in your life, for example, as you mentioned, your wedding or a summer in your life, or graduation, or some other happy time that they've had.  If that were the case, then we didn't use those participants or those particular stimuli in our experiments because we had to try to rule it out.  Having said that, this is something that can happen unconsciously.  People wouldn't necessarily be aware of the fact that they do have some sort of a memory associated with this piece of music.  So, in our next experiments, we'll be using new music that people have never heard before and try to see if we can replicate these findings with something that they can't have any previous memories associated with.

Kat -   So what is it in music that makes us have this emotional experience?  Is there any information about - is it a specific tune or chord sequences?

Valorie -   Well it seems to be somewhat different for different people which is really what's fascinating about it because it seems to be very much a cognitive reward.  It's almost as if our experience of pleasure to it is also is dependent on how we're following the tone sequences that we hear.  An example of this is that if you hear a single tone, that's not really pleasurable for you, but if you hear a series of these single tones over time, that can become some of the most pleasurable and intense experiences that humans have ever reported.  So, how exactly does this happen?  David Heron for example has a book called Sweet Anticipation and he explains this very nicely where we develop a sense of anticipation to where these notes are going to go, and then our expectations can either be confirmed or we may be surprised but either way, it seems like composers sort of know this and they try to manipulate our emotional arousal with the way that they're sequencing these tones.  This is probably why our appreciation of music is partly cortical or intellectual, or cognitive if you will. 

Our results actually provide very nice evidence to support this hypothesis because we found that right before we combined our PET procedure with fMRI so we can get some temporal information on what's happening in the brain as well.  We found that right before this peak emotional response which we measured by chills for example in our study,  participants were actually showing dopamine release in different regions of the reinforcement circuit that has very strong connections with the frontal cortex.  Now, the frontal cortex of the brain is a part that's highly developed in humans and it's basically what separates us from lower order primates and it houses complex thinking.  So, what we see here is evidence of this complex or abstract appreciation of an aesthetic stimulus which in this case is music, is also tapping into the same dopaminergic system that reinforces the most fundamentally rewarding and biologically adapted behaviours such as food and sex.  The same system also produces the same intense euphoric feelings of addictive drugs, such as cocaine.

Kat -   Wow!  That's absolutely fascinating and as a musician, I hope you find out what the key is, to making everyone love your music.  That is Valerie Salimpoor from McGill University in Canada and you can find more about that story -  it's published online in the journal Nature Neuroscience this week.