How One Simple Exercise Improves Overall Motor Skill: New Neuroscience Discovery

In a new publication coming out of the University of California, San Diego, neuroscientists have discovered a novel mechanism by which our brains learn new motor skills (Li & Spitzer, 2020). While neuroscience research can be daunting, let’s try and parse it out and see just what’s so exciting about these findings.

There is a part of the mammal brain called the caudal pedunculopontine nucleus (cPPN). Caudal is a Latin term that defines a section anatomy that is “below,” so in this context it means a bottom part of the brain. The cPPN is located low in the brain within the brainstem. 

Understanding how the brain is built will help clear up what it means that the cPPN is in the low brainstem. Our brains are built, evolutionarily, from the bottom up, meaning that the lowest parts are the oldest, reptilian brain, all the way up to our prefrontal cortex just behind our forehead, which is newly human. The cPPN, then, being low in the brain, is an old part of the brain regulating the most basic parts of our selves, such as balance, breathing, heartbeats and sleep. The cPPN itself controls motor coordination. 

What does “motor coordination” mean? Imagine yourself trying to throw a basketball into a hoop. Your arm has to project the right way, your fingers have to let the ball roll off correctly, your legs have to step forwards to balance your body and your eyes have to track the trajectory. The cPPN, low in the brain, helps coordinate all that. 

These University of California neuroscientists learned something new by watching mice exercise. They divided the mice in their study into two groups. The first group they allowed to exercise by running on a wheel, while the second group they did not. The neuroscientists then observed the mice and noticed that the ones who ran on the wheel were better at also at staying up on a rotating rod and not falling off as they ran across a balance beam. All these motor tasks involved different muscles, different coordination, different skills. So why did becoming good at one (running on the wheel) also improve ability at all the others? 

The neuroscientists looked into the mice’s brains. They noticed that the mice who ran on the wheel showed a remarkable change within their cPPN. Before the mice’s running exercise, the cPPN neurons in the mice’s brains used the neurotransmitter called acetylcholine to communicate. After the running exercise, however, the same cPPN neurons switched to use a different neurotransmitter called GABA to communicate. Acetylcholine is an excitatory neurotransmitter, meaning that it “excites” that neuron in order to send a signal. GABA, on the other hand, is an inhibitory neurotransmitter. Rather than excite a neuron, GABA opens a channel that allows negatively charged ions through. This rush of negative charge reduces the excitability of the neuron, thereby “inhibiting” a signal being sent.

Acetylcholine and GABA, with their differing effects on neurons, have been shown to play important roles within the brainstem. Past research has shown that the two interact in a complicated dance with each other, sometimes even being released at the same time, balancing out the effects of each other (Granger, et al., 2016; Pfeiffer-Linn & Glantz, 1989). However, the neuroscientists conducting the study at hand were surprised to see the cPPN switch use from acetylcholine to GABA. The neuroscientists even found that if they disallowed the switchover from acetylcholine to GABA to happen in the cPPN, then the original benefits of exercise in the mice did not occur. Thus, they knew that something about this switchover was essential to one type of exercise improving ability in all types of exercise. Motor skills and learning improved due, at least in part, to this switch.

What can the neuroscientists do with this finding? Well, it is an exciting beginning. The neuroscientists noted that one possible avenue for the future is seeing how the mechanism can be used. For example, maybe if the switch between the neurotransmitters could be induced by a pill or other means, the effect of improved exercise ability would follow after. Could motor skills be benefitted even without the original exercise? Maybe there are implications for those suffering from motor-related neurological disorders. 

What can you do with these findings? One of the neuroscientists who conducted the study, Li, says, "For people who would like to enhance their motor skill learning, it may be useful to do some exercise to promote this form of plasticity to benefit the brain. For example, if you hope to learn and enjoy challenging sports such as surfing or rock climbing when we're no longer sheltering at home [due to COVID-19], it can be good to routinely run on a treadmill or maintain a yoga practice at home now” (Li & Spitzer, 2020). So, perhaps, take up any form of exercise now during the pandemic, knowing that it will benefit you in other forms of exercise later in this year.

References

Granger, A. J., Mulder, N., Saunders, A., & Sabatini, B. L. (2016). Cotransmission of acetylcholine and GABA. Neuropharmacology, 100, 40–46. 

Li, Hq., Spitzer, N.C. Exercise enhances motor skill learning by neurotransmitter switching in the adult midbrain. Nat Commun 11, 2195 (2020).

Pfeiffer-Linn, C., & Glantz, R. M. (1989). Acetylcholine and GABA mediate opposing actions on neuronal chloride channels in crayfish. Science, 245(4923), 1249-1251.

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