How Does the Brain Unconsciously Master Automatized Skills?

A new study links implicit learning and lateral regions of the cerebellum.

Posted Jan 31, 2018

Wikipedia/Public Domain
Human brain viewed from below, showing cerebellum (Latin for "little brain") and brainstem.
Source: Wikipedia/Public Domain

Specific regions of the cerebellum are key to implicit memory and play an important role in acquiring automatized skills that someone can perform without conscious awareness or “over-thinking” the process, according to a growing body of evidence. For example, a recent study, “Implicit Learning Deficit in Children with Duchenne Muscular Dystrophy: Evidence for a Cerebellar Cognitive Impairment?” identified a link between procedural (implicit) memory, the lateral cerebellum, and cerebral cortex connectivity with the basal ganglia via cerebro-cerebellar networks. These findings were published January 16, 2018, in the journal PLoS ONE

To learn more about the difference between declarative (explicit) memory and procedural (implicit) memory see: "Language Utilizes Ancient Brain Circuits That Predate Humans" and "The Mysterious Neuroscience of Learning Automatic Skills." This one-minute video shows how automatized typing utilizes implicit procedural memory without explicit knowledge of where the keys are on the keyboard:As an athlete, I’ve been fascinated with the role that the cerebellum plays in sports performance and implicit memory ever since I was a young, fledgling tennis player. My late father, Richard Bergland, M.D., was a neuroscientist, neurosurgeon, and author of The Fabric of Mind (Viking). He was also my tennis coach. My dad's Norwegian grandparents were immigrants who came to America without any merit-based skills. His parents were poor and could not afford college. In the 1930s, during the dust bowl era and Great Depression, my missionary grandparents headed from Minnesota to the badlands of Montana, where my father was born.

As part of his American dream, my father got a scholarship to college based on his sports ability. Dad credited the implicit memory he pounded into his cerebellum by religiously hitting a tennis ball against a backboard using a beat-up, hand-me-down racquet with his athletic prowess. As a teenager, "Dick" Bergland became the Montana state tennis champion. In college, he played varsity tennis and squash. Racquet sports were his ticket out of poverty and into New York City's Cornell Medical School, where I was born. When looking back on his career, my father would say, “Of this I am absolutely certain, becoming a neurosurgeon was a direct consequence of my eye for the ball.”

Courtesy of Kay Bergland
Richard M. Bergland, M.D. credited his mastery of automatized tennis skills with functions of the cerebellum. As a neurosurgeon, he strongly believed that performing brain operations relied much more on implicit/procedural memory than the explicit/declarative memory he acquired in the library. 
Source: Courtesy of Kay Bergland

As a neuroscience-based tennis coach, dad would constantly say to me: “Chris, think about hammering and forging implicit muscle memory into the Purkinje cells of your cerebellum with every stroke.” He believed that the key to avoiding what tennis legend Arthur Ashe referred to as “Paralysis by analysis” was to make one's tennis game more automatized/cerebellar and less intellectual/cerebral. (Cerebellar is the sister word to cerebral and means ‘relating to or located in the cerebellum.')

"We don't know exactly what the cerebellum is doing. But whatever it's doing, it's doing a lot of it. —Richard Bergland, M.D. (20th-century neurosurgeon and neuroscientist)

Much of what we know about how the human cerebellum functions is based on the observation of atypical cerebellar structure or dysfunction caused by injury or disease and subsequent documentation of changes in learning and behavior.

Based on his observation of patients with cerebellar lesions and other evidence about the cerebellum available in the late-20th century, my dad had a hunch that automatized learning and implicit memory were tied to cerebellar structure and function. That said, prior to recent 21st-century advents in technology, it was impossible to prove his hypotheses about the cerebellum in a laboratory. Therefore, he would speculatively say, “We don’t know exactly what the cerebellum is doing. But whatever it’s doing, it’s doing a lot of it.”

Luckily, before his death in 2007, I was able to collaborate with my father while writing the manuscript for my first book, The Athlete’s Way: Sweat and the Biology of Bliss (St. Martin’s Press). During this period, we spoke every day. And, I picked his brain to learn as much as I could about how the mind, body, and brain work in unison based on his lifelong acquisition of explicit knowledge regarding neuroscience.

At the time, my dad couldn’t get his visionary ideas about the cerebellum published in peer-reviewed journals. So, after I broke a Guinness World Record and got a book deal, I was determined to use my platform as an athlete and author to publish his radical ideas about the cerebellum. Because my writing was geared towards a mainstream audience, we were able to bypass the Ivory Tower gatekeepers of academia and advance pioneering, fresh ideas that challenged the status quo. 

Photo and illustration by Christopher Bergland (Circa 2007)
This diagram illustrates the earliest incarnations of the "Bergland Split-Brain Model" and elucidates various hypothetical roles the cerebrum and cerebellum might play within dynamic cerebellar-cerebral cortex brain systems. (From p. 81 of The Athlete's Way: Sweat and the Biology of Bliss)
Source: Photo and illustration by Christopher Bergland (Circa 2007)

Together, my father and I created a split-brain model we called “up brain-down brain.” This was a direct and cogent response to the infamous “left brain-right brain” model. Part of our motivation to shift the conversation towards 'up-down' interplay between the cerebrum and cerebellum was that my dad had gotten tangled up in some of the controversy surrounding “left brain-right brain” when he was chief of neurosurgery at Harvard Medical School’s Beth Israel Hospital. (e.g., He served as the medical expert for a bestselling book called Drawing on the Right Side of the Brain.)

Later in life, my father's thinking had evolved to believe that the relationship between both hemispheres of the cerebrum (Latin for ‘brain’) and both hemispheres of the cerebellum (Latin for ‘little brain’) should be included in research and discussions about the interplay between the left-right hemispheres of the cerebral cortex.

There is an important caveat: Obviously, the entire brain works in concert as a whole and overly generalizing brain structure and functional connectivity based on split-brain models can be too simplistic. That being said, let’s get back to the nitty-gritty details of the aforementioned January 2018 study led by Stefano Vicari from the Department of Neurosciences and Neurorehabilitation at Ospedale Pediatrico Bambino Gesù in Rome, Italy.

For this study, Vicari et al. focused on individuals affected by Duchenne Muscular Dystrophy (DMD) without intellectual disability and compared them to an age-matched cohort of typically developing (TD) children. The researchers used a modified version of the Serial Reaction Time Task (SRTT) designed to measure implicit sequence learning abilities.

As the authors explain, “In this study, the SRTT was administered to a group of DMD children without intellectual disability and to TD controls in order to investigate their implicit learning and, consequently, their cerebro-cerebellar network function. More specifically, we wished to establish whether the SRTT can detect signs of implicit learning difficulties in a group of children with DMD without intellectual disability, and whether these were related to the mutation site. SRTT is capable to analyze the implicit sequence learning and to demonstrate the role of the cerebellum and its circuits as a key structure for this function.”

The researchers administered these tests to 32 Duchenne children and 37 controls of comparable chronological age. Notably, the Duchenne group showed a reduced rate of implicit learning even in the absence of global intellectual disability.

As the authors write: “It appears that there is a specific impairment in implicit and procedural learning, as observed in adults with cerebellar lesions, affecting the lateral regions of the cerebellum. The role of the cerebellum in the deficits in implicit learning and procedural learning has also been observed in children with acquired neurological disease and developmental dyslexia or intellectual disabilities. The cerebellum appears to have an important role in detecting and recognizing event sequences and in acquiring and automatizing new cognitive procedures.”

Stefano Vicari and collaborators sum up their findings: “In conclusion, our study documented a deficit in implicit learning in a sample of boys with DMD without intellectual disability. On the basis of our knowledge, this deficit may be interpreted as the expression of a dysfunction of the cerebellum and, more specifically, of the lateral regions of the cerebellum and its networks connections.”

References

Stefano Vicari, Giorgia Piccini, Eugenio Mercuri, Roberta Battini, Daniela Chieffo, Sara Bulgheroni, Chiara Pecini, Simona Lucibello, Sara Lenzi, Federica Moriconi, Marika Pane, Adele D’Amico, Guja Astrea, Giovanni Baranello, Daria Riva, Giovanni Cioni, Paolo Alfieri. “Implicit Learning Deficit in Children with Duchenne Muscular Dystrophy: Evidence for a Cerebellar Cognitive Impairment?” PLoS ONE (Published: January 16, 2018) DOI: 10.1371/journal.pone.0191164

Ulrike Schara, Melanie Busse, Dagmar Timmann, and Marcus Gerwig. "Cerebellar-Dependent Associative Learning Is Preserved in Duchenne Muscular Dystrophy: A Study Using Delay Eyeblink Conditioning." PLoS ONE (Published: May 14, 2015) DOI: 10.1371/journal.pone.0126528

Kristy M. Snyder, Yuki Ashitaka, Hiroyuki Shimada, Jana E. Ulrich, Gordon D. Logan. "What Skilled Typists Don’t Know About the QWERTY Keyboard." Attention, Perception, & Psychophysics (2014) DOI: 10.3758/s13414-013-0548-4