The cerebellum has a unique and very complex, regular structure. At the 2022 IAPCT conference, I suggested that this structure could facilitate transformations between levels of the perceptual hierarchy, the organization and modulation of afferent perceptual input functions and efferent reference input functions. (My 2022 presentation can be downloaded from here.)
There are diverse kinds of evidence supporting this. For example, research shows that error engages the cerebellum:
“It is widely accepted that unexpected sensory consequences of self-action engage the cerebellum. However, we currently lack consensus on where in the cerebellum, we find fine-grained differentiation to unexpected sensory feedback. … [L]imitations of functional magnetic resonance imaging to probe the cerebellum could play a role as climbing fiber activity associated with feedback error processing may not be captured by it.” (Johnson et al. 2019)
The use of the same kind of neural structures for physical configuration and relationship control for abstract ‘cognitive’ control of concepts and relationships is affirmed by the correlation of physical activity with dementia (Wanigatunga et al 2025).
Cerebellar deficiencies are involved in autism spectrum disorders (ASD):
“Notably, individuals with ASD have demonstrated difficulties generating implicitly derived behavioral predictions and adaptations. Although many brain regions are involved in these processes, the cerebellum contributes an outsized role to these behavioral functions. Consistent with this prominent role, cerebellar dysfunction has been increasingly implicated in ASD.”
(Kelly et al. 2021)
Ted Cloak proposed this role of the cerebellum in a general way on CSGnet in 2014, based on evolutionary developmental considerations, as did Frans Plooij in conversation with me at the 2019 (pre-pandemic) Manchester conference when I inquired about developmental stages after the 70th week and the postulated establishment of the highest level of the Powers control hierarchy.
In an immediate reply to Ted in October 2014, Richard Kennaway counterposed the (very rare) cases of people born without a cerebellum, saying “I don’t know what to make of all that.” This came up naturally in discussion of my Manchester presentation.
In all cases of injury or defect in the cerebellum, not as well as in such cases of cerebellar agenesis, it is clear that other parts of the brain reorganize to perform the socially demanded functions, with diminished capabilities. I have been looking for studies that investigate how other parts of the brain are changed and engaged, that could be quite illuminating.
The abstract below summarizes the kinds of affective and social consequences of these adaptations:
“In this case series we describe neuropsychiatric disturbances in adults and children with congenital lesions including cerebellar agenesis, dysplasia, and hypoplasia, and acquired conditions including cerebellar stroke, tumor, cerebellitis, trauma, and neurodegenerative disorders. The behaviors that we witnessed and that were described by patients and families included distractibility and hyperactivity, impulsiveness, disinhibition, anxiety, ritualistic and stereotypical behaviors, illogical thought and lack of empathy, as well as aggression and irritability. Ruminative and obsessive behaviors, dysphoria and depression, tactile defensiveness and sensory overload, apathy, childlike behavior, and inability to appreciate social boundaries and assign ulterior motives were also evident. We grouped these disparate neurobehavioral profiles into five major domains, characterized broadly as disorders of attentional control, emotional control, and social skill set as well as autism spectrum disorders, and psychosis spectrum disorders. Drawing on our dysmetria of thought hypothesis, we conceptualized the symptom complexes within each putative domain as reflecting either exaggeration (overshoot, hypermetria) or diminution (hypotonia, or hypometria) of responses to the internal or external environment. Some patients fluctuated between these two states.”
(Schmahmann et al. 2007)
If anyone can find reports of research showing which and how other parts of the brain compensate for cerebellar defects, that would be a very useful contribution to this topic.
Johnson JF, Belyk M, Schwartze M, Pinheiro AP, Kotz SA. (2019). The role of the cerebellum in adaptation: ALE meta-analyses on sensory feedback error. Hum Brain Mapp 40.13:3966-3981. doi: 10.1002/hbm.24681. Epub 2019 Jun 2. PMID: 31155815; PMCID: PMC6771970.
Kelly, Elyza; Christine Ochoa Escamilla, Peter T. Tsai. (2021). Cerebellar Dysfunction in Autism Spectrum Disorders: Deriving Mechanistic Insights from an Internal Model Framework. Neuroscience 462:274-287. ISSN 0306-4522. URL:
Redirecting.
(https://www.sciencedirect.com/science/article/pii/S0306452220307296)
Schmahmann, J.D., Weilburg, J.B. & Sherman, J.C. The neuropsychiatry of the cerebellum — insights from the clinic. Cerebellum 6, 254–267 (2007). https://doi.org/10.1080/14734220701490995
Wanigatunga, Amal A., Yiwen Dong, Mu Jin, Andrew Leroux, Erjia Cui, Xinkai Zhou, Angela Zhao, Jennifer A. Schrack, Karen Bandeen-Roche, Jeremy D. Walston, Qian-Li Xue, Martin A. Lindquist, & Ciprian M. Crainiceanu. (2025). Moderate-to-Vigorous Physical Activity at any Dose Reduces All-Cause Dementia Risk Regardless of Frailty Status. Journal of the American Medical Directors Association 26.3:105456. DOI: 10.1016/j.jamda.2024.105456