As kids, once we have mastered the complex motor skill of riding a bicycle, we’re told that its a lifelong skill that we’ll never forget. Getting all of the moving parts of human and machine in sync with each other becomes a collective memory that can be called on from age 6 to 60. Which is surprising, knowing that names, numbers and recent locations of car keys can be so easily forgotten. What makes motor skills stick in our brains, ready to be called on at anytime? According to two teams of cognitive science researchers, we can thank a property called neuroplasticity which actually changes the structure of our brain as we learn.
Much like bike riding, mastering ice skating requires some advanced balance and coordination to stay upright. Knowing when and how much to lean to one side or the other while arms and legs are swinging is the type of parallel processing computation that human brains can handle well.
Tucked underneath the larger cerebral hemispheres in the brain, the cerebellum is known to play an active role in controlling movement by taking in messages from the spinal cord, combined with signals from other parts of the brain, and coordinating the precision and timing of complex motor skills. Damage to the cerebellum causes a lack of coordination, much like being under the influence causes someone to stagger and lose their balance.
Neuro researcher Im Joo Rhyu, from the Korea University College of Medicine, knew from prior studies that intensive motor skill training, such as juggling or basketball, resulted in physical changes in the brain as measured by functional magnetic resolution imaging (fMRI). Now, he wanted to find out if the ability of the brain to adapt itself over time, known as neuroplasticiy, was sport-specific. Given that the cerebellum has a right and a left hemisphere, would the physical growth in neural connections be symmetric on both sides?
His research team chose the perfect sport to investigate, speed skating. Being able to chase opponents around a tight oval at high speeds on ice is a showcase for the cerebellum’s functions. The key difference is that skaters always turn counterclockwise or left around the track. Years and years of practice to perfect movement in one direction may show a growth pattern in the brain different from other sports, Rhyu hyphothesized.
So, he compared the fMRI brain scans of 16 male, professional, short-track speed skaters with the scans of 18 male, non-skaters who didn’t even exercise. As predicted, in the experienced skaters, the right hemisphere of their cerebellums were larger than the left side. Since the skaters only turn to the left, they spend much more time balanced on their right foot with short steps on their left. Standing on your right foot activates the right side of the cerebellum. In addition, learning a motor skill that requires constant visual monitoring and adjustments is also thought to occur mainly in the cerebellum’s right half.
The study appears, appropriately, in the December 2012 issue of The Cerebellum.
Size is not all that changes in the cerebellum after repeated training. The increased network of neuron connections between brain cells also increases to the point of being noticeable on a different type of brain scan, known as diffusion tensor imaging (DTI). Using this technology, a research team examined experts in a different sport, karate.
“Most research on how the brain controls movement has been based on examining how diseases can impair motor skills,” said Dr Ed Roberts, from the Department of Medicine at Imperial College London, who led the study. “We took a different approach, by looking at what enables experts to perform better than novices in tests of physical skill.
They compared the punch strength of twelve karate fighters who had achieved black belt status and had an average of almost 14 years of experience with 12 control subjects who exercised regularly but had no karate training. Karate punching is not simply a feat of raw muscular strength. It is combination of speed and the coordination of wrist, shoulder and torso movement.
As expected, they found that the punch strength of the black belts was substantially greater than the novices. But the DTI scan also showed something else very interesting. The white matter of their cerebellums, which is made up of the tangled network of neuron connections carrying signals from one cell to another, was structurally different than in the beginner’s brains.
The results of the study are published in the journal Cerebral Cortex.
“The karate black belts were able to repeatedly coordinate their punching action with a level of coordination that novices can’t produce,” said Roberts. “We think that ability might be related to fine tuning of neural connections in the cerebellum, allowing them to synchronise their arm and trunk movements very accurately.”
It is reassuring for athletes to know that all of those hours devoted to training their skills are actually reshaping and rebuilding their brain architecture. And for us bike riders, we can understand how the skinned knees and bruised elbows we endured when the training wheels came off were worth the effort to program a skill that will last a lifetime.