Thursday, 28 May 2020
Dancing (like playing music) alters your brain if you do it a lot
The various brain-imaging techniques that have been available for some decades now have made it possible to observe the structural anatomical changes that occur in the brains of people who engage regularly in a given a activity, such as dancing or playing music. Today I want to talk about research on these changes that has been conducted recently by Falisha Karpati of McGill University in Montreal. In her 2017 study entitled “Dance and music share gray matter structural correlates”, she compared the brains of professional dancers with those of professional musicians, on which more research had previously been done. In her 2018 study, “Structural Covariance Analysis Reveals Differences Between Dancers and Untrained Controls”, she compared the brains of professional dancers with those of control subjects who had no dance training. In these two studies, Karpati found that dancing or playing music for eight hours every day does indeed make one’s brain different from those of people who do neither.
But different in what way? The changes that Karpati observed consisted in thickening of certain areas of the cerebral cortex, a layer of neurons that is normally only 2 to 3 millimetres thick. And (although Karpati’s studies don’t mention this fact directly), many other studies have shown that one of the aspects of the neuronal plasticity responsible for this thickening appears to be the development of new dendrites in cortical neurons that are activated frequently.
As Karpati explains in a short video interview, among all the parts of the cerebral cortex that may be activated when someone dances or plays music, there are two particular areas whose volume she found to be appreciably greater in dancers and musicians than in her control subjects. The first of these areas was the right superior temporal gyrus (see illustration above), which is involved in many functions, including integration of auditory, visual, somatosensory and other sensory inputs as well as sensory and motor integration, all of which are, of course, important aspects of dance and music.
The other area was the left dorsolateral prefrontal cortex, which has a special relationship to dancing. This part of the brain becomes active when someone is observing body movements with the goal of reproducing them (and may involve the activity of mirror neurons). It also becomes active when someone engages in motor mental imaging (either imagining themselves performing a movement or trying to predict what movement another person is going to make).
So, as the reporter asks Karpati in the interview, did dancing a lot really cause these areas of the dancers’ cortexes to thicken, or did these individuals become dancers because they were born with these parts of their cortexes more developed than other people’s, which made it easier for them to achieve a high level of dance performance?
Karpati thinks that the answer may be: a bit of both. She did not study the same individuals before and after they became professional dancers, so she has no way of proving either possibility. But she does note that other longitudinal studies have shown that practicing dance for an extended time does increase the volume of these brain structures. Other studies have shown that subjects who were not dancers but in whom these brain structures were larger did in fact learn more quickly how to dance. But this does not tell us whether these brain structures had been larger from birth. They may also have grown larger at least partly as the result of other motor learning that these individuals did in which these structures were activated.
As Karpati says toward the end of her interview, we now have a good idea of the changes that the brain undergoes after repeated dance practice. We also now know the activation patterns in the brains of people watching other people dance (and even how these patterns differ according to whether the people watching know how to dance the particular dance they’re watching). The next step will be to record the overall brain activity of people while they are actually dancing. That would scarcely be practical with the bulky equipment now used to do magnetic resonance imaging. But new technologies such as near-infrared spectroscopy use equipment so light that it can be incorporated into a headband that someone can wear while dancing. Thus we might well soon be able to watch the cortexes of dancers at work in real time (the cortexes, mind you, and not the entire brain, because one of the limitations of this technology is that it cannot capture images any deeper into the brain).
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