Why Music Makes Our Brain Sing
http://www.nytimes.com/2013/06/09/opinion/sunday/why-music-makes-our-brain-sing.html?src=ISMR_AP_LO_MST_FB
MUSIC is not tangible. You can’t eat it, drink it or mate
with it. It doesn’t protect against the rain, wind or cold. It doesn’t vanquish
predators or mend broken bones. And yet humans have always prized music — or
well beyond prized, loved it.
In the modern age we
spend great sums of money to attend concerts, download music files, play
instruments and listen to our favorite artists whether we’re in a subway or
salon. But even in Paleolithic times, people invested significant time and
effort to create music, as the discovery of flutes carved from animal bones
would suggest.
So why does this
thingless “thing” — at its core, a mere sequence of sounds — hold such
potentially enormous intrinsic value?
The quick and easy
explanation is that music brings a unique pleasure to humans. Of course, that
still leaves the question of why. But for that, neuroscience is starting to
provide some answers.
More than a decade
ago, our research team used brain imaging to show that music that people
described as highly emotional engaged the reward system deep in their brains —
activating subcortical nuclei known to be important in reward, motivation and
emotion. Subsequently we found that listening to what might be called “peak
emotional moments” in music — that moment when you feel a “chill” of pleasure
to a musical passage — causes the release of the neurotransmitter dopamine, an
essential signaling molecule in the brain.
When pleasurable
music is heard, dopamine is released in the striatum — an ancient part of the
brain found in other vertebrates as well — which is known to respond to
naturally rewarding stimuli like food and sex and which is artificially
targeted by drugs like cocaine and amphetamine.
But what may be most
interesting here is when this neurotransmitter is released: not only when the
music rises to a peak emotional moment, but also several seconds before, during
what we might call the anticipation phase.
The idea that reward
is partly related to anticipation (or the prediction of a desired outcome) has
a long history in neuroscience. Making good predictions about the outcome of
one’s actions would seem to be essential in the context of survival, after all.
And dopamine neurons, both in humans and other animals, play a role in
recording which of our predictions turn out to be correct.
To dig deeper into
how music engages the brain’s reward system, we designed a study to mimic
online music purchasing. Our goal was to determine what goes on in the brain
when someone hears a new piece of music and decides he likes it enough to buy
it.
We used
music-recommendation programs to customize the selections to our listeners’
preferences, which turned out to be indie and electronic music, matching Montreal’s hip music
scene. And we found that neural activity within the striatum — the
reward-related structure — was directly proportional to the amount of money
people were willing to spend.
But more interesting
still was the cross talk between this structure and the auditory cortex, which
also increased for songs that were ultimately purchased compared with those
that were not.
Why the auditory
cortex? Some 50 years ago, Wilder Penfield, the famed neurosurgeon and the
founder of the Montreal Neurological Institute, reported that when
neurosurgical patients received electrical stimulation to the auditory cortex
while they were awake, they would sometimes report hearing music. Dr.
Penfield’s observations, along with those of many others, suggest that musical
information is likely to be represented in these brain regions.
The auditory cortex
is also active when we imagine a tune: think of the first four notes of
Beethoven’s Fifth Symphony — your cortex is abuzz! This ability allows us not
only to experience music even when it’s physically absent, but also to invent
new compositions and to reimagine how a piece might sound with a different
tempo or instrumentation.
We also know that
these areas of the brain encode the abstract relationships between sounds — for
instance, the particular sound pattern that makes a major chord major,
regardless of the key or instrument. Other studies show distinctive neural
responses from similar regions when there is an unexpected break in a
repetitive pattern of sounds, or in a chord progression. This is akin to what
happens if you hear someone play a wrong note — easily noticeable even in an
unfamiliar piece of music.
These cortical
circuits allow us to make predictions about coming events on the basis of past
events. They are thought to accumulate musical information over our lifetime,
creating templates of the statistical regularities that are present in the
music of our culture and enabling us to understand the music we hear in
relation to our stored mental representations of the music we’ve heard.
So each act of
listening to music may be thought of as both recapitulating the past and
predicting the future. When we listen to music, these brain networks actively
create expectations based on our stored knowledge.
Composers and
performers intuitively understand this: they manipulate these prediction
mechanisms to give us what we want — or to surprise us, perhaps even with
something better.
In the cross talk
between our cortical systems, which analyze patterns and yield expectations,
and our ancient reward and motivational systems, may lie the answer to the
question: does a particular piece of music move us?
When that answer is
yes, there is little — in those moments of listening, at least — that we value
more.
Robert J. Zatorre is a professor of neuroscience at the
Montreal Neurological Institute and Hospital at McGill University.
Valorie N. Salimpoor is a postdoctoral neuroscientist at the Baycrest Health
Sciences’ Rotman Research Institute in Toronto.