Research breakthrough highlights cerebellum’s role
By Heather Allen
Pioneering new research on the role of the cerebellum could lead to an effective treatment for autism.
The research forms part of a study by Professor Frank Van Overwalle, from the Brain, Body, and Cognition research group at Vrije Universiteit Brussel (VUB). The study highlights the cerebellum’s crucial role in both motor coordination and social-cognitive functions, expanding its known importance beyond just movement control. According to Professor Van Overwalle, this research offers a fresh perspective on the cerebellum’s role and paves the way for new treatments for psychiatric and neurological conditions, such as autism spectrum disorders.
The results of magnetic brain stimulation tests on autistic subjects were used in the study. The subjects showed measurable improvements when performing a sequence of cognitive tasks. More complex tasks are now being tested to see if further improvements can be made, with the goal of developing practical treatments for people with autism.
The aim of the research is to highlight the underappreciated role of the cerebellum in both motor functions and social-cognitive processes. The research supports a growing trend in neuroscience, which has historically concentrated more on the cerebrum, the larger, main part of the brain.
Although small compared to the rest of the brain, the cerebellum holds more than half of the neurons in the body. Often referred to as the back brain, the cerebellum is located at the back of the head, just above and behind where the spinal cord connects to the brain, at ear-level. The cerebellum forms a half-circle shape around the brain stem, which connects the brain to the spinal cord. It is easily identifiable by the series of horizontal grooves from top to bottom. The average adult cerebellum is about 11.5cm wide, between 3-4cm tall in the middle and 5-6cm on the sides, and weighs between 136-169 grams.
Although unusual, research on the cerebellum is nothing new. Over two hundred years ago, scientists started analysing the cerebellum by studying people with cerebellum damage. Subjects often had trouble keeping their balance or would have difficulty reaching for objects. Later, evidence was found that cerebellum damage could have other effects, including difficulty in learning new words or skills.
Crucially, the posterior cerebellum has a critical role in human social and emotional learning and decision making. Three systems and related neural networks support this cerebellar function: a biological action observation system; a mentalising system for understanding a person’s mental and emotional state; and a limbic network supporting core emotional pleasure/displeasure and arousal processes. The study describes how these systems and networks support social and emotional learning via connections initiating and terminating in the posterior cerebellum and cerebral neocortex.
Professor Van Overwalle’s research tests the hypothesis that a major function of the cerebellum is to identify and encode temporal sequences of events. Researchers believe that this function might help to fine-tune and automatise social and emotional learning. The study discusses tests conducted using neuroimaging and non-invasive stimulation that provide evidence for cerebellar sequencing, as well as accounts of the cerebellum’s role in these social and emotional processes.
For decades, the cerebellum was primarily associated with motor coordination, Professor Van Overwalle explains: “People with cerebellar abnormalities often experience motor issues. For example, they struggle to smoothly touch their nose with a finger. These difficulties highlight the cerebellum’s essential role in refining motor movements.”
The research extends beyond motor functions, exploring the cerebellum’s involvement in social and cognitive abilities. Professor Van Overwalle’s findings reveal that abnormalities in the cerebellum not only lead to motor deficits but are also linked to emotional and behavioral disorders. According to Professor Van Overwalle, research on individuals with autism demonstrates how non-invasive brain stimulation techniques like magnetic stimulation can improve social task performance.
Another breakthrough highlighted in the study is the use of transcranial electrical stimulation (tES), a cheaper and more accessible technique compared to magnetic stimulation. While the effects of tES are still limited, the research group is committed to further development, seeing its potential for wide-scale application in the future.
“Our hope is to refine these techniques further to improve social and cognitive functions in people with autism,” Professor Van Overwalle says.
Source: Social and emotional learning in the cerebellum by Frank Van Overwalle, 21 October 2024, Nature Reviews Neuroscience.