Life Sciences Database/Wikimedia Commons
Cerebellum (Latin for "little brain") in red. 
Source: Life Sciences Database/Wikimedia Commons

In 1504, Leonardo da Vinci made wax castings of the human brain and coined the term "cerebellum" (Latin for little brain) after he identified two small brain hemispheres neatly tucked under the relatively humongous left-right hemispheres of the "cerebrum" (Latin for brain). Cerebellar is the sister word to cerebral and means 'relating to or located in the cerebellum.'

Historically, the cerebellum was considered by most experts to be a "non-thinking" brain structure that did little more than help coordinate fine-tuned motor skills and maintain balance. However, there is mounting empirical evidence that our "little brain" plays a surprisingly large role in emotional processing, cognitive function, and our overall mental health.

Two decades ago, when Jeremy Schmahmann of Harvard Medical School first proposed his "Dysmetria of Thought" hypothesis—which posits that our cerebellum may fine-tune emotions and cognition much the same way it fine-tunes coordinated muscle movement—most of his colleagues were skeptical of this radical new theory.

Today, there is a growing pile of clinical research suggesting that Schmahmann is onto something with his pioneering work on "cerebellar cognitive affective syndrome." CCAS and Schmahmann's dysmetria of thought hypothesis challenged the traditional notion that the cerebellum is only responsible for regulating motor functions. Increasingly, experts agree with Schmahmann that the cerebellum and cerebellar functional connectivity play a critical role in both motor and nonmotor functions. 

For example, a first-of-its-kind study on cerebellar functional connectivity with other brain regions recently identified previously unrecognized changes in cerebellar connectivity resulting from a targeted mind-body intervention (MBI) used to reduce traumatic stress symptoms experienced by cancer patients. These findings were published online October 19 in the Journal of Cancer Survivorship.

During this study, researchers from the Marcus Institute of Integrative Health at Thomas Jefferson University examined alterations in cerebellar connectivity after patients coping with cancer-related emotional trauma practiced a mind-body intervention called NET (Neuro Emotional Technique). The Marcus Institute regularly uses NET to help cancer patients process trauma-related emotions. Neuro Emotional Technique allows the practitioner to simultaneously gauge his or her subjective stress responses by monitoring how the nervous system is reacting to distressing stimuli using biofeedback tools.

Courtesy of Larry Vanderverte
Although the cerebellum is only about 10 percent of total brain volume, it houses the majority of our brain's total neurons. Based on this disproportionate distribution of neurons, one could speculate that "whatever the cerebellum is doing, it's doing a lot of it."
Source: Courtesy of Larry Vanderverte

To evaluate the neurophysiological effects of this treatment, the researchers conducted resting-state functional blood oxygen level-dependent (BOLD) magnetic resonance imaging (rs-fMRI) before and after the NET intervention. Additionally, autonomic nervous system (ANS) activity was measured using heart rate response to a specific traumatic stimulus. Pre/post comparisons were also performed between the NET and waitlist control groups.

Interestingly, the researchers found that Neuro Emotional Technique triggered changes in functional connectivity between the cerebellum (including the vermis) and the prefrontal cortex, amygdala, parahippocampus, and brain stem. These changes in cerebellar connectivity were associated with reduced levels of emotional distress. In the study's abstract, the authors note, "Specifically, functional connectivity between the cerebellum and the amygdala and prefrontal cortex appear to be associated with a reduction in autonomic reactivity in response to distressing cancer-related memories.”

In a statement, principal investigator, Daniel Monti, M.D., who is Senior Vice President and Director of the Marcus Institute of Integrative Health, said:

"This is the first study that offers a demonstrable solution for cancer patients with traumatic stress symptoms. It also expands our understanding of the importance of the cerebellum in coordinating traumatic emotions, and the body's response to them. The results of this study are a breakthrough in understanding how an intervention like NET works, particularly in regard to the cerebellum's role in the regulation of emotional experiences. We now understand that the cerebellum does much more than coordinate motor activity.”

The best news for anyone suffering from post-traumatic stress disorder or other types of debilitating anxiety is that Neuro Emotional Technique appears to alleviate distress on a neurobiological level. "Just four to five brief NET sessions result in significantly less emotional and physical distress, and these improvements are associated with connectivity changes throughout the brain," Monti said in a statement. "Patients, even those who were skeptical at first, have reported the NET intervention as 'diffusing a bomb' on 'the worst anxiety ever.'"

These are exciting times for state-of-the-art cerebellar research. I've been writing about the cerebellum for over a decade and am thrilled to see that our "little brain" is finally getting the scientific recognition it deserves. Future studies will undoubtedly help us figure out what those 69 billion neurons housed in the cerebellum are actually doing. Please stay tuned for more cutting-edge empirical research on the cerebellum.

References

Monti, Daniel A., Anna Tobia, Marie Stoner, Nancy Wintering, Michael Matthews, Chris J. Conklin, Feroze B. Mohamed, Inna Chervoneva, Andrew B. Newberg. "Changes in Cerebellar Functional Connectivity and Autonomic Regulation in Cancer Patients Treated with the Neuro Emotional Technique for Traumatic Stress Symptoms." Journal of Cancer Survivorship (First published online: October 19, 2017) DOI: 10.1007/s11764-017-0653-9

Schmahmann, Jeremy D. "Dysmetria of Thought: Clinical Consequences of Cerebellar Dysfunction on Cognition and Affect." Trends in Cognitive Sciences (1998) DOI: 10.1016/S1364-6613(98)01218-2

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