I’m Not All Ears: Movement in Music Matters Too
We hear music, yes, but we feel and even see it, too. Here I’ll describe some research showing how music is so much more than sounds, and that movement is important for processing music. People are inherently rhythmic on multiple levels. From the circadian rhythms that govern biological processes to our heartbeat, which is with us from birth, periodic and semi-regular events are pervasive in our lives. One periodicity with which we are obsessed is “the beat” in music. We love the beat, and often fully rely on it when enjoying music. Losing the beat is somewhat discomforting to people, but it is usually very easily found again, as seen in these babies (watch at least until 1:10 ):
And that is what is so amazing about musical rhythms: we automatically extract the beat and make sense of all these sounds over time, even as babies. The beat doesn’t even need to be heard to exist, as is the case when counting through rest or silence in music. The beat persists even when the sound does not. But how?
Our amazing brains! Of course when we hear music it has to go through our auditory cortex, the part of the brain that enables us to perceive sounds. But the organization of sounds over time is handled largely by motor regions in the brain. In other words, the parts of our brain that let us move voluntarily (as opposed to a reflex, which is involuntary) also help us process musical rhythms and beats. For example, participants in one study were scanned in an fMRI machine while listening to beat-based rhythms, or irregular rhythms with no sense of beat. The brain scan showed much more activation during the beat-based rhythms than the irregular ones in the basal ganglia (BG)—a region used for starting a series of movements—and in the supplementary motor area (SMA), which is used for planning actions. Why didn’t the irregular rhythms work? Probably because our brains are good at finding patterns, and irregular rhythms don’t have easy patterns. This means that music with a distinct beat activates brain regions used in movement, even when we’re not moving. This could be why we are compelled to move, even just by tapping a foot, when listening to music. The beat is stimulating our movement planning neurons. Interestingly, if the beat is too fast or too slow, the BG and the SMA won’t activate which is why we love dancing to music around 120bpm: it is right in the middle of our brain’s sensitive range of tempi.
Some really great research is exploring how musical beats can help patients of Parkinson’s disease. Parkinson’s kills neurons in the BG, making it difficult to start movement and continue movement fluidly. If instructed to move with a musical beat, however, patients seem to improve their gait, and decrease the time it takes to go from sitting to walking. Researchers theorize that patients struggle to create an internal pace for moving because the neurons needed have died, and the beat is compensating for the dead neurons by giving a regular pace to which they can refer. Obviously, Parkinson’s hasn’t been cured, but this is amazing and could lead to some great rehabilitation therapies.
Let’s look at music one level up from the beat: meter. Depending on how the beats are grouped, we perceive different meters. Groups of three beats, as in a waltz, we call triple meter, and groups of two beats, as in almost all other music we hear, is duple meter. But again, it’s not just about hearing, it’s about moving. In one study, participants heard a rhythm sequence that was neither duple nor triple. Then, their heads were put onto little seesaws and the experimenter would rock them (the most relaxing experiment ever?) either every two, or every three beats. Then, they heard a duple meter and a triple meter rhythm and had to say which one was most similar to what they heard during the rocking. They tended to pick whichever meter they were rocked to. This shows that the way we move our heads can affect the way we perceive music. But how? Well, our ears have little fluid-filled tubes that make up our “vestibular system.” This system helps us with orientation and (back to our main theme) movement, telling us how we are physically positioned at any time. The vestibular systems communicates with many brain regions, including the insula. The insula help assimilate a lot of different information over short periods of time. So, it may be combining the auditory information (the rhythms) with the vestibular information (the rocking) that is happening at the same time, at the same rate. Thus, the way we move helps us perceive music, and can even change the way we perceive music.
Phillips-Silver, J. & Trainor, L.J. (2008). Vestibular influence on auditory metrical interpretation. Brain and Cognition, 67, 94-102. http://www.jessicaphillips-silver.com/wp-content/uploads/2013/01/Phillips-Silver_Trainor_Brain_Cogn_2008-copy.pdf
Nombela, C., et al. Into the groove: Can rhythm influence Parkinson’s disease? Neuroscience and Behavioral Reviews, (2013). http://www.sciencedirect.com/science/article/pii/S0149763413001930
Grahn, J.A. & Watson, S.L. (2013). Perspectives on rhythm processing in motor regions of the brain. Music Therapy Perspectives, 31, 25-31. http://mtp.oxfordjournals.org/content/31/1/25.full.pdf+html
Image source: openclip.org