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Your Left Cerebellar Hemisphere May Play a Role in Cognition
The left hemisphere of the cerebellum may play a role in cognitive function.
Posted September 17, 2016
Brand new, cutting-edge research was unveiled yesterday which shows a correlation between brain volume in the left hemisphere of the cerebellum (Latin for “little brain”) and cognitive function. This is a groundbreaking discovery. Historically, the cerebellum has been considered by most neuroscientists to be the seat of non-thinking brain activities such as fine-tuning and coordinating muscle movement. Until recently, the cerebellum was never thought to be involved in cognition.
Here's a quick background sketch of the cerebellum and some terminology: Cerebellar is the sister word to cerebral and means “relating to or located in the cerebellum.” There are two cerebral hemispheres located in the cerebrum (left brain-right brain) and there are two cerebellar hemispheres located in the cerebellum.
In 1504, Leonardo da Vinci made wax castings of the human brain and coined the term “cerebellum” after noticing two small "little" brain hemispheres tucked neatly under the larger cerebrum. Although the cerebellum is only 10% of brain volume, the cerebellar hemispheres house well over 50% of your brain’s total neurons.
Your left cerebellar hemisphere works in conjunction with the right hemisphere of your cerebrum to control muscle movements on the left side of your body; your right cerebellar hemisphere and the left hemisphere of your cerebrum control the right side of your body.
My father, Richard Bergland, was a world-renowned neurosurgeon, neuroscientist, and author of The Fabric of Mind. In the 1970s, he was partially responsible for promoting the notion that the “right brain” was our creative brain and the “left brain” was our academic brain. He brought this message to a general audience through his own writing and as the medical consultant for people like Betty Edwards, who wrote Drawing on the Right Side of the Brain.
Later in his life, my dad regretted that he'd erroneously advocated the “left brain-right brain” model so strongly and that it had become a type of consensus gentium in the pop psychology representation of neuroscience.
In the late-20th century, my father began to hypothesize that both hemispheres of the cerebellum also played an important role in cognitive function and creative thinking. Unfortunately, once the genie was out of the bottle, there was no way to stop the “right brain” juggernaut of creative capacity being solely associated with the right hemisphere of the cerebrum from hogging the spotlight in mainstream media.
Near the end of his career, my father became infamous in academia for being an iconoclast who vehemently refused to maintain the status quo. He was a visionary who liked to push new boundaries—but he was also a rageaholic and burned a lot of bridges professionally. Most of his peers in the medical establishment labeled him a heretic, a lunatic, or both. Although his skills as a neurosurgeon were undeniable, he alienated most of his allies at peer-reviewed neuroscientific journals and didn't have an outlet for getting his ideas published.
Therefore, when I got a book deal with St. Martin’s Press in 2005 to write a book about neuroscience, mindset, and athletic performance, I had a stealth agenda to use my platform as a writer to get my father’s radical ideas about the cerebellum to a mainstream audience. Because I’m an athlete and not a scientist, I would repeatedly say that the revolutionary ideas I presented about the cerebellum a decade ago were an ‘educated guess' and 'hunches' based on conversations with my father. Below is a snapshot of p. 81 from The Athlete's Way. The dichotomy of each column represents a speculative framework for "up brain-down brain."
While writing the manuscript for The Athlete’s Way: Sweat and the Biology of Bliss, I spoke with my father every day. Together, we created the “Bergland Split-Brain Model” which we referred to as ‘up brain-down brain.’ The ‘up’ brain included both hemispheres of the cerebrum, and the 'down' brain included both hemispheres of the cerebellum. This was a direct and cogent attempt to shift the focus from east-west across the corpus callosum to north-south across the midbrain. I realize now, that as part of my system of belief and creating a new paradigm, the 'up brain-down brain' framework was an important stepping stone, but not completely accurate.
As a father-son team, my dad and I worked well together. I was able to take his very complicated ideas about neuroscience and filter them into relatable layperson's terms. That said, there was a Wizard of Oz aspect to my writing about neuroscience a decade ago because 99% of what I wrote about the brain came straight from my father, who was metaphorically hidden behind a curtain whispering everything I had to say about the brain into my ear. From an archetypal perspective, he was my Obi-Wan Kenobi training me to become a Jedi Master in terms of better understanding the mysterious and underestimated powers of the cerebellum.
When my father died abruptly in 2007, my world was turned upside down. I was overcome with a tidal wave of grief. Although I was terrified to pursue neuroscience without his guidance, at his funeral, I made a vow to pick up the torch and do the best I could to continue my father’s work and vindicate his name by decoding the enigmatic cerebellum. Every morning, I wake up hoping there will be a new study that helps us better understand how each hemisphere of the cerebellum and cerebrum work together in concert to optimize cognitive flexibility and creative capacity.
In 2009, I had a Eureka moment and a serendipitous breakthrough about how all four brain hemispheres work together, which led to the sketch above. One day, I was walking home from the gym when I bumped into a poet friend of mine, Maria, on Commercial Street in Provincetown. Maria and I had a conversation about what we were writing, and I told her about a book I was working on at the time, Origins of Imagination, which looked at how physical activity stimulates creative thinking via the cerebellum.
As I spoke, Maria started to mime being on an elliptical trainer by moving her legs and arms back and forth. Then she said, “I don’t know what it is, but whenever my arms and legs are in a bi-pedal motion, poetry just pours out of me.” I said, “Aha! That’s it!" Instantly, I got a crystal clear visualization of the 'Super 8' image above with green and yellow arrows representing the back and forth interplay between all four brain hemispheres like a Möbius strip. I rushed home and drew the rudimentary sketch you see here in less than 5 minutes.
In 2015, I was listening to NPR one morning, when I heard a piece about the work that Jeremy Schmahmann is doing at Harvard Medical School with patients who have ataxia and cerebellar damage. Through his research at Mass General Hospital, Schmahmann has developed a theory called “Dysmetria of Thought” which is basically the hypothesis that the cerebellum fine-tunes cognitive thinking the same way it fine-tunes muscle movements. This was another light-bulb moment for me. Thank you again for all of your groundbreaking research on the cerebellum, Jeremy Schmahmann.
Gray Matter Volume in the Left Cerebellum May Predict Aspects of Cognitive Function
Because of my passion and curiosity to learn more about the cerebellum, I was thrilled to wake up this morning and read about a brand new study that is still unpublished, “Role of Cognitive Reserve on Cognitive Function and Regional Brain Atrophy in Multiple Sclerosis: a Two-Year Longitudinal Study,” which was presented yesterday at ECTRIMS 2016 (September 14-17) in London, UK.
This research was led by Maria Assunta Rocca, M.D., Ph.D., of the Division of Neuroscience at Vita-Salute San Raffaele University in Milan, Italy. The goal of her work is to examine whether the cognitive reserve hypothesis—in which enriching experiences protect against cognitive decline and dementia—can predict cognitive decline as well as gray matter and white matter volume changes in patients with multiple sclerosis (MS).
The researchers found that enriching experiences may have a protective role in cognitive performance in multiple sclerosis, by reducing the effect that gray matter atrophy has on cognitive functions. They also found that gray matter volume in the left cerebellar hemisphere and other brain regions predicted levels of cognitive function on certain verbal and attention tests.
Although these findings are preliminary, I have a hunch that in years to come more neuroscientists will continue to identify how “microzones” within each hemisphere of the cerebellum have direct interplay with “microzones” within each hemisphere of the cerebrum. Again, this is pure conjecture on my part and still an educated guess. That said, stay tuned for future empirical evidence to support my hypothesis!
To read more about the cerebellum, check out my previous Psychology Today blog posts,
- "Harvard Research Shows How the Cerebellum Regulates Thoughts"
- "Enhanced Cerebellum Connectivity Boosts Creative Capacity"
- "The Cerebellum Many Be the Seat of Creativity"
- "5 Reasons the Cerebellum Is Key to Thriving in a Digital Age"
- "The Cerebellum Deeply Influences Our Thoughts and Emotions"
- "Your Cerebellum May Dictate How Your Brain Handles Alcohol"
- "Cerebellum Damage May Be the Root of PTSD in Combat Veterans"
- "More Research Links Autism and the Cerebellum"
- "Epigenetic Mechanism in the Cerebellum Drives Motor Learning"
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