Our brains process music via different sensory pathways depending on what we think its source is, a new study finds.
As our brains organize information from our senses into a coherent representation of the world around us, they’re constantly hard at work associating data from one sense – say, sight – with data from another – say, hearing.
A lot of the time, this process is pretty straightforward – for instance, if we see a man talking and hear a nearby male voice, it’s typically safe for our brains to assume the voice “goes with” the man’s lip movements. But it’s also not too hard for others to trick this association process – as anyone who’s watched a good ventriloquism act knows.
Now, as the journal Proceedings of the National Academy of Sciences (PNAS) reports, a team led by HweeLing Lee and Uta Noppeney at the Max Planck Institute for Biological Cybernetics has discovered a way in which musicians‘ brains are specially tuned to correlate information from different senses when their favorite instruments are involved.
Neuroscientists have known for years that the motor cortex in the brains of well-trained guitar and piano players devotes much more processing power to fingertip touch and finger movement than the same area of a non-musician’s brain does. But what this new study tells us is that the brains of pianists are also much more finely-tuned to detect whether a finger stroke is precisely synchronous with a sound produced by the touch of a piano key.
To figure this out, the team assembled 18 pianists – amateurs who practice on a regular basis – and compared their ability to tell synchronous piano tones and keystrokes from slightly asynchronous ones while they lay in an fMRI scanner (presumably by showing them this video). The researchers also tested the pianists’ ability to tell when lip movements were precisely synchronized with spoken sentences.
The team then compared the musicians’ test results against the results of equivalent tests taken by 19 non-musicians. What they found was pretty striking:
Behaviorally, musicians exhibited a narrower temporal integration window than non-musicians for music but not for speech. At the neural level, musicians showed increased audiovisual asynchrony responses and effective connectivity selectively for music in a superior temporal sulcus-premotor-cerebellar circuitry.
In short, pianists are much more sensitive to a slight asynchrony between a keystroke and a piano tone than non-musicians are – but this sensitivity doesn’t also apply to speech and lip movements. In other words, pianists’ brains are unusually sensitive to asynchrony only when it involves piano keystrokes.
Another important finding is that the researchers could predict how sensitive the musicians would be to asynchrony based on asynchronies the fMRI scanner detected in their motor cortex:
Our results suggest that piano practicing fine tunes an internal forward model mapping from action plans of piano playing onto visible finger movements and sounds.
This means there’s a direct link between inter-neural coordination and ear-eye coordination. I don’t know about you, but I think that’s pretty incredible.
The researchers hope that as they study similar data from musicians who work with other instruments, they’ll come to better understand how our brains learn to associate stimuli from one sense from information from another – and maybe even how they learn when and when not to “sync up” these stimuli in our subjective experience of reality.
It’s too bad we can’t hook up the brain of, say, Mozart or Hendrix to an fMRI scanner – who knows what amazing discoveries we might make. But even so, I’m sure you can think of some living musical geniuses whose brains you’d like to see in action.