The Secret Behind Sophisticated Movements... Found in Cerebellar 'Astrocytes' [Reading Science]

Uncovering the Principles of Motor Coordination Development through the Integration of AI, Computational Modeling, and Neuroscience
Expectations for Applications in Research on Motor Disorders such as Parkinson's Disease, as well as in Robotics and Physical AI

The core mechanism underlying the sophisticated motor coordination abilities observed when humans walk or run has been found to originate from 'astrocytes,' a type of non-neuronal cell in the cerebellum. This study presents a new concept in brain development, proposing that the cooperative structure between neurons and glial cells drives the maturation of motor functions, moving beyond the traditional view that brain development is centered solely around neurons.

On March 9, the research team led by Changjoon Lee, Director of the Cognitive and Glia Science Group at the Center for Cognition and Sociality of the Institute for Basic Science (IBS), along with Research Fellow Seongho Hong, announced that they had identified the mechanism by which astrocytes in the cerebellum regulate neural circuits to enable complex and precise movements.

A conceptual diagram illustrating changes in cerebellar circuits and differences in motor coordination with growth. In young mice, inhibitory signals formed primarily in neuron-centric circuits dominate, resulting in repetitive and limited walking patterns. In contrast, in adults, astrocytes also participate in regulating inhibitory signals, enabling flexible combination of diverse movements for motor coordination. Provided by the research team

Changes in Cerebellar Inhibitory Signals... Astrocytes Take the Lead in Regulation

The cerebellum contains more than 70% of the brain's total neurons, most of which are cerebellar granule cells. These cells are regulated through 'tonic inhibition,' a process in which their activity is continuously suppressed by the neurotransmitter GABA. The research team focused on the possibility that the regulatory mechanism for these inhibitory signals might change during growth.

Experiments showed that, in juvenile mice, GABA released from inhibitory neurons was responsible for tonic inhibition. However, in adults, astrocytes played a central role in inhibitory regulation by directly supplying GABA through an ion channel called 'Bestrophin-1.' In other words, as development progresses, the cerebellar circuit transitions from a neuron-centered system to a system in which both neurons and astrocytes jointly regulate neural activity.

The Key to Cerebellar Motor Coordination... Confirmed by AI Behavioral Analysis

To analyze the impact of this transition on neural circuit function, the research team constructed a large-scale computational model of the cerebellar neural circuit, incorporating approximately one million neurons. Simulation results showed that as astrocytes became the main regulators of inhibition, interference between granule cells decreased, allowing them to process different movement information more independently.

Verification of Motor Coordination Function of Astrocyte-Derived GABA through AI-Based 3D Behavior Analysis. (a) Videos from five cameras filmed from multiple angles were processed using the AI-based analysis system (AVATAR) to extract coordinates of key body points of mice, which were then used to reconstruct 3D skeletal movements. (b) Analysis of the reconstructed 3D skeletal data revealed that the loss of astrocyte-derived GABA in adults reduces limb movement independence, leading to impaired motor coordination. Provided by the research team

In addition, using the deep learning-based three-dimensional behavioral analysis system 'AVATAR 3D,' the team conducted a detailed analysis of mouse movements. In normal adult mice, a wide variety of motor patterns were observed, with limb movements being independently combined. In contrast, juvenile mice or adult mice lacking the Bestrophin-1 gene exhibited a significant reduction in movement diversity.

The research team explained that these findings demonstrate, not only at the cellular level but also in actual behavioral changes, that cerebellar astrocytes are key regulators of the maturation of motor coordination abilities.

Changjoon Lee, Director of the IBS Center for Cognition and Sociality, stated, "This study demonstrates that interactions with astrocytes, as well as with neurons, play a crucial role during brain development," adding, "We expect these findings to be applied not only in research on developmental and degenerative motor disorders, but also in the development of movement control technologies for robots and physical AI based on brain principles."

The results of this study were published online on February 18 in the international journal 'Experimental & Molecular Medicine.'

This content was produced with the assistance of AI translation services.