The Neuroscience of Superfluid Thinking
Cerebellum (Latin: “little brain”) in yellow. Cerebellar means “relating to the cerebellum”. The cerebro-cerebellar circuits connect the two cerebral hemispheres to the left and right cerebellar hemispheres.
Source: decade3d – anatomy online/Shutterstock
Until recently, the human cerebellum was primarily considered a region of the brain whose sole job was to coordinate motor movements. most neuroscientists did not believe that the cerebellum facilitated non-motor cognitive functions. But around 1998, at the dawn of the 21st century, this view of the cerebellum focused solely on motor function began to change. Today, most neuroscientists agree that our so-called “little brain” plays an important role in cognition.
In this article, I will filter two articles from January 2022 that put brain-cerebellar functional connectivity in the spotlight through the lens of an “up brain-down brain” model that my neuroscientist father and I created at the beginning of the 2000s.
The first item (McAfee, Liu, Sillitoe and Heck, 2022) presents a new theory for how the cerebellum coordinates neural communication in the cerebral cortex. The second item (Li et al., 2022) examines how cerebro-cerebellar connectivity between microareas of the cerebellum and specific regions of the brain affects verbal fluency during language tasks.
The cerebro-cerebellar circuits coordinate the movement of fluids
In the 1970s, as a beginner tennis player, Arthur Ashe and Björn Borg were my role models.
Borg was known for his cool (almost “frosty”) Swedish temper and grace under pressure. Ashe was a trailblazer who said, “There’s a thing in sports called ‘paralysis by analysis.'” My neurosurgeon father, who wrote The fabric of the mindfiltered their playing styles through brain science.
When training me to play as Borg, Dad focused on hacking the vagus nerve by taking a deep diaphragmatic inhale followed by a long, slow exhale before each serve. This breathing technique activated my parasympathetic nervous system and eased fight or flight stress. When training me to play as Ashe, Dad focused on not “overthinking” by loosening up my cerebral cortex and relying on cerebellar muscle memory.
This sagittal cerebro-cerebellar diagram illustrates Bergland’s split-brain model and was published in “The Athlete’s Way”.
Source: Photo and illustration by Chris Bergland (circa 2005)
In the mid-2000s, I was writing The athlete’s way; and my father was the book’s medical advisor. From a neuroscience perspective, our goal was to provide readers with a novel split-brain model that would help them optimize flow states, experience superfluidity, and achieve peak performance.
Because the cerebellum has long been known to play a central role in coordinating muscle movement, we hypothesized that athletes could improve the fluidity of their motor coordination by emphasizing the importance of bottom-up processing.
On the other hand, too much top-down brain processing would disrupt the flow and was likely to cause an overthinking athlete to choke due to “analysis paralysis”.
Namely, the cerebrum (“big brain”) has two cerebral hemispheres, and the cerebellum (“small brain”) has two cerebellar hemispheres. When coordinating fluid movements, the right cerebellar and left cerebral hemispheres work together to coordinate motor skills on the right side of the body and vice versa.
The criss-crossing functional connectivity of the “upper brain” is essential for creating superfluidity in sport. Interestingly, left-brain thinking also benefits from robust connectivity to the right cerebellar hemisphere, and whole-brain thinking benefits from all four cerebral hemispheres working in synchrony.
For example, in right-handers who tend to have most of their language functions in the left cerebral hemisphere, microzones in the right cerebellar hemisphere coordinate language tasks (Li et al., 2022). During language tasks involving the left cerebral hemisphere, regions of the right cerebellar hemisphere (eg, lobule VI, Crus I, and Crus II) are activated as part of a cerebro-cerebellar loop.
Cerebro-cerebellar circuits can coordinate superfluid cognitive processes
As an athlete, my interest in optimizing the functional connectivity of the four cerebral hemispheres was directly related to improving my athletic performance by facilitating perfectly coordinated frictionless flow (i.e. superfluidity) .
As a writer, I realized that whenever I felt a state of flux typing over 100 words per minute using the cerebellar muscle memory I had established in a typing class in high school, my thought was also superfluous.
Anecdotally, as a retired ultramarathon runner who still enjoys jogging, I’ve observed that my creative thinking and writing process benefit from cardio. New ideas seem to spring from my subconscious when I jog, and it’s much easier to connect seemingly unrelated ideas while performing moderate to vigorous physical activity.
One day in 2009, as I was walking home from the gym, I ran into an old friend named Maria, who is a poet and who had also just finished a workout. We started discussing how cardio workouts seemed to improve our ability to create language. She said, “Poetry flows from me every time I’m on the elliptical,” while moving her arms and legs in a bipedal motion.
In a flash, as Maria mimicked the back and forth motions of being on an elliptical trainer, I visualized a two-way feedback loop between the four cerebral hemispheres creating a cerebral-cerebellar loop that looks like a number 8 And I imagined how this circuit could facilitate fluency. I rushed home and drew a rudimentary “Super Eight” brain map (below).
This brain map illustrates how robust cerebro-cerebellar connectivity could facilitate superfluidity in sports and during the writing process.
Source: Photo and illustration by Chris Bergland (circa 2009)
Without explicitly referring to neuroscience, Joyce Carol Oates has vividly described how certain prose captures the “fluidity of movement” and how, throughout her writing career, daily jogs have helped her “maintain a voice coherent and fluid” when writing a novel.
In a 1999 room for the New York Times’ arts section, “To invigorate literary minds, start moving literary feet,” Oates explains how running expands his consciousness and allows him “to envision what I’m writing as a movie or a dream.” She goes on to say:
“Running, the spirit flies with the body; the mysterious efflorescence of language seems to pulse in the brain, to the rhythm of our feet and the swinging of our arms. The structural problems that I encounter while writing, during a long hectic, frustrating and sometimes desperate morning of work, for example, I can usually solve by running in the afternoon.“
Cerebellar dysfunction can cause uncoordinated thinking
by Jeremy Schmahmann Thought dysmetria The hypothesis posits that a well-functioning cerebellum can coordinate thoughts just as it coordinates movements.
Conversely, a dysfunctional cerebellum can cause uncoordinated movements or, in some cases, disorganized thinking. Schmahmann is a neurologist and cerebellar ataxia specialist at Mass. General Hospital of Harvard Medical School. Ataxia means “lack of coordination” in Greek.
In the late 20th century, Schmahmann noticed that some patients with lesions in specific microareas of the cerebellum did not exhibit physical ataxia but appeared to have difficulty coordinating their thoughts.
In 1998, Schmahmann coined the term “thought dysmetria”. In the same year, he published a landmark article describing cerebellar cognitive affective syndrome (CCAS). At the time, it was a radical notion to speculate that the cerebellum was involved in non-motor functions such as cognition.
Fast forward to 2022. We now have more and more evidence that the cerebellum plays an important role in coordinating cognitive processes.
Figure 1. (A) Cerebro-cerebellar interaction via reciprocal connections between specific cerebral and cerebellar areas. (B) Cerebellar modulation of communication between cerebral cortical areas. Here, the cerebellum coordinates communication by increasing the coherence of neural oscillations in a task-specific way.
Source: McAfee, Liu, Sillitoe and Heck/Creative Commons Attribution License (CC BY)
In their January 2022 open access article, “Cerebellar Coordination of Neuronal Communication in Cerebral Cortex”, first author Samuel McAfee et al. explain how the cerebellum coordinates and optimizes cerebral cortical communication during cognitive processes just as it optimizes motor coordination. Their Figure 1 illustration (above) shows these cerebro-cerebellar functions in action.
Going forward, we need more research to better understand how cerebro-cerebellar connectivity coordinates fluid thought.