The Under-Appreciated Cerebellum
The general consensus on the human cerebellum is that it’s a part of the “reptilian brain,” the region of the brain concerned with the essential functions of life – eat, sleep, reproduce, et cetera. Most of the cerebellum’s responsibilities include controlling body movement. Alternatively, the prefrontal area of your brain is what’s considered to be the “human brain,” responsible for abstract thought that allows us to invent language and mathematics, create music, and build advanced social relationships.
It wouldn’t be ridiculous to assume that these two brain regions aren’t related. These are two completely separate areas of the brain, right?
That was the common belief up until Rodney Swain - the dean of the College of Letters and Science at UW-Milwaukee – found that the cerebellum has a larger role than previously thought. In a study on social interaction in rats, Swain and his students used an experiment to discover that the cerebellum also has a role in social behavior. While it may sound trivial, this discovery could actually have some major implications.
“It turns out that when we damage the cerebellum, the connections to the prefrontal cortex begin to atrophy,” Swain says. “And it’s that lack of connectivity that causes the alterations.”
The experiment involved turning off a certain part of the cerebellum in a rat and then seeing how it interacted with others rats. Normally, rats socialize in many ways like touching noses, grooming each other, and engaging in playful wrestling. However, when the neuroscientists turned off the fastigial nuclei in the cerebellum, the rats’ social behavior was changed drastically. The affected rats avoided social contact by shortening interaction time, hiding from others, and even sitting on other rats to stop them from having to interact.
Given that it is clear that a damaged cerebellum can affect social skills, the problem the research now faced was to fix it. Swain’s team used a set of various mazes to strengthen the spatial reasoning skills, which is a set of skills that is focused in the cerebellum.
The research showed that the rats with damaged cerebellums signaled symptoms of ADHD, which impaired them on spatial reasoning tasks like the Morris Water Maze.
A follow-up study took it a step further by performing the same experiment, but gave the rats an easier maze to practice with before the Morris Water Maze.
The difficult mazes served as a spatial reasoning task while the easier mazes served as a working memory task - prominent in the prefrontal brain - as they had to use their prefrontal areas to communicate with the cerebellum to complete the Morris Water Maze. Pairing the two memory and reasoning skill tasks proved to strengthen the atrophying connections between the cerebellum and the prefrontal cortex.
“What we were able to show was that we can create at least one of the symptoms of ADHD or an autism spectrum disorder by giving a lesion to a small area of the cerebellum, and then we can reverse that deficit by behavioral intervention,” Swain says.
Careful research showed with alarming strength that the cerebellum seems to have some role in how we interact socially. The how’s and why’s are left to speculation until further research is conducted, but it has very interesting indications for human use.
“We can become far more focused and very specific in how we try to treat these disorders, rather than a treatment that affects multiple brain systems that are not involved,” Swain says.
Stay tuned to the series to find out how Swain used this research to lead a small study on human children that could provide a method of treating autism and ADHD – without the use of drugs.
Cheers, nerds.
