Last week I had the pleasure to watch people expressively jump, fall, run, and spin, all to the beat of music. Where could I see this moving art in the city of lights? The Palais Garnier hosts variety of shows including opera, concert, and, in my case, a ballet. As a person who can’t walk across a flat surface without tripping, I was amazed to see the unfathomable poise the dancers had in their movement. They could perfectly match complex poses and key beats of the music with a grace unfounded in the dancing my friends and I did in the Latin District discotheques. Nevertheless, over the next week I discovered whether you have the grace of a ballerina, a mosh pit, or an audience member during Fête de la Musique, all of our brains possess circuitry that enables our bodies to “move to the music.”
Four photos from the performance I attended: Bertaud / Bouché / Paul / Valastro at Palais Garnier. Taken from https://www.operadeparis.fr/en/season-16-17/ballet/bertaud-bouche-paul-valastro.
What came first: dance or music? A popular hypothesis addressing this “chicken or the egg” question promotes dance preceded music as dance is an application of motoric abilities essential for survival in most animals (Dean, Byron, and Bailes 2009). However, as music promotes reproductive success and enrichment of cultural capital, the two probably had a mutual factor encouraging their coevolution: rhythm. Rhythm perception has been consistently traced to brain areas such as the premotor and supplementary motor areas and the basal ganglia. Damage to these areas has caused timing issues (Grahn and Brett 2007). For instance, patients that have Parkinson’s Disease, a disorder affecting the basal ganglia, struggle with walking at a rhythmic pace (Grahn and Brett 2007).
Taken from http://antranik.org/wp-content/uploads/2011/11/basal-ganglia-caudate-nucleus-and-putamen-and-thalamus-and-tail-of-caudate-nucleus.jpg
Supplementary Motor Area. Taken from https://static1.squarespace.com/static/52ec8c1ae4b047ccc14d6f29/t/576f2964b3db2bd35f648444/1490438406965/supplementary-motor-area.jpg
Recent research has better elucidated how our bodies perceive and synchronously move with different rhythms. A typical lab test for rhythm involves tapping alongside a beat that may fluctuate in speed. A 2016 study used this set up as participants sat in a dMRI, an MRI imaging machine that specifically tracks water movement in your brain. dMRI is a useful technique for visualizing the highways that carry information across your brain, called white matter tracts. The goal of the study was to investigate what “highways” are used most when syncing movements to a beat. During the task, they averaged the asynchrony between the beat and the participant’s tapping as well as how long it took the participant to adjust when the beat became faster or slower. The imaging system tracked increased water flow to particular brain regions, thus implying more activity along that highway when conducting the task.
Typical DTI image showing tracts of brain that send information to other brain areas. Taken from https://www.healthcare.siemens.nl/magnetic-resonance-imaging/options-and-upgrades/clinical-applications/syngo-resolve.
The study found syncing movements to the beat lead to more activity in the frontal area of the left arcuate fasiculus (Blecher, Tal, and Ben-Sachar 2015). As the arcuate fasiculus is an important connection highway between your main auditory perception area and premotor areas, it is no wonder stronger connections between these two areas promote better synchronization. In the context of the ballerinas at Palais Garnier, strong connections along the arcuate fasiculus are necessary for performing jumps and plies on the beat.
Correlational image of left arcuate fasiculus activation with mean asynchrony (Blecher, Tal, and Ben-Sachar 2015).
Arcuate Fasiculus. Taken from https://clinicalgate.com/wp-content/uploads/2015/03/B9780702037382000322_f032-001-9780702037382.jpg
The study also suggests people who are consistently better staying on beat have more activation along their temporal callosal segment(Blecher, Tal, and Ben-Sachar 2015). Callosal segments are highways known to connect the right and left sides of your brain. If we were to image a ballet dancer’s brain to mine, we would likely find stronger connections along the temporal callosal segment in the graceful ballerina than the clumsy college student. But what happens when the music becomes faster mid-performance? In this case, the study suggests our brains adjust to the new time via activation of the precentral callosal segment, another right-left brain highway by the motor regions of the brain (Blecher, Tal, and Ben-Sachar 2015). Overall, this research paper concluded highways on your left side of the brain connecting your auditory and motor areas and particularly activated when predicting and comparing auditory inputs and motor commands. Additionally, they concluded motor and premotor highways, which join the left and right side of brain, particularly activates when adjusting to a beat change(Blecher, Tal, and Ben-Sachar 2015).
dMRI image of participants brain. Precentral callosal segment shown in pink along side graph reflecting correlation between activation of segment with resynchronization time. (Blecher, Tal, and Ben-Sachar 2015).
Precentral gyrus where the pre central callosal segment connects the two hemispheres of the brain. Taken from https://www.kenhub.com/en/atlas/gyrus-precentralis
While this paper explains how we perceive and adjust to music beat, I would love to see more studies that particularly investigated rhythm changes in music. Jazz, for example, has a swing rhythm that doesn’t necessarily stay to one beat pace the whole song. I am curious if some music is easier to sync to your movements to than others. While I am pretty good at dancing on beat to a typical pop song, other genres of music like heavy metal may be more difficult to dance to because of the rhythmic beat inherent to the genre. Future experiments could possibly compare listeners with artists who specifically play that genre as well as artists who play a separate genre of music. I would expect artists of that genre would have stronger brain activation among rhythm-perception pathways when listening to their own music compared to artists who play a different genre or an average listener. Future experiments such as that one may better elucidate my understanding of why humans enjoy coordinating our bodies alongside a great song.
Bibliography
Blecher T, Tal I, Ben-Sachar M (2015). White matter microstructural properties correlate with sensorimotor synchronization abilities. NeuroImage 138:1-12
Grahn JA and Brett M (2007) Rhythm and beat perception in motor areas of the brain. Journ Cog Neurosci 19 (5): 893-906
Dean RT, Byron T, Bailes FR (2009). The pulse of symmetry: On the possible co-evolution of rhythm in music and dance. Musicae Scientiae 341-367.
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