The cerebellum, the little structure in the back of the brain, is crucial for movement and plays many regulatory roles that aid in behavioral tasks, motor coordination, and motor learning (Reeber et al., 2013). One circuit within the cerebellum, the Purkinje circuit, is responsible for the regulation and coordination of motor movements (Paul & Faten Limaiem, 2021). Cerebellar stellate cells (CSC) are tiny neurons (cells that are responsible for brain function) that are intricately woven together with other cells in the Purkinje circuit. While current research has observed the function of CSCs, the question of how CSCs exert control on the Purkinje circuit remains. New research published in Scientific Reports has found a way to isolate CSCs and examine how they modulate other cells. Through isolating CSCs and stimulating the Purkinje circuit, researchers found CSCs reduced the stimulation passed along the Purkinje circuit, thus regulating it (Rizza et al., 2021). Understanding the role of CSCs offers new focuses for research and treatment regarding movement disorders, neurodevelopmental disorders like autism spectrum disorder, and neurodegenerative disorders like Parkinson’s.  

Cerebellar stellate cells are inhibitory cells in the cerebellum that control the activity of Purkinje cells (Liu, 2013). Purkinje cells are large branching cells, much like tree roots, that release a chemical that decreases motor activity, allowing for coordination of movements (“Purkinje Cell | Anatomy | Britannica,” 2022). CSCs and basket cells, other inhibitory cells within the Purkinje circuit, help control the activation of it, and through control over Purkinje cells, motor function (Liu, 2013). However, because of how intertwined CSCs and basket cells are, isolating the exact contributions of CSCs has remained difficult. Because motor function requires many complex processes, each step in motor activation/regulation must be examined. To examine the Purkinje circuit, staining procedures are used to visualize the cells, external stimulation of the cells, and chemical examinations to determine CSCs functionality and structure. 

In attempts to further clarify the role of CSCs within the brain, researchers used brain slices from male and female mice to record electrical currents of CSCs (Rizza et al., 2021). The experimenters first had to visualize the CSCs in the mouse cerebellum through various recording measures. Once visualized, researchers tested how CSCs were affected by different levels of stimulation. The data gathered from the recordings of CSC stimulation is one of the first detailed models of a small set of CSCs (Rizza et al., 2021). The data gave a clear picture of the thresholds at which CSCs inhibit Purkinje cells and how CSCs act as low-pass or band pass filters. Low pass/band pass filters allow stimulation at specific levels; if the stimulation is above the cutoff level, the filters decrease the signals until they fall below the cutoff level (Wikipedia Contributors, 2022). Showing that CSCs act as low-pass filters gives insight into their role in the Purkinje circuit. For example, whatever stimulation the CSCs receive, they will only pass along a limited amount to Purkinje cells which makes the Purkinje cells less likely to stimulate other cells. Researchers also found that a proportionally larger number of CSCs were needed to inhibit Purkinje cell activity than previously thought (Rizza et al., 2021). 

Understanding the stimulation required and transmission of CSCs is vital to understanding how to induce synaptic plasticity within the Purkinje circuit. Synaptic plasticity is the concept that neuronal connections within the brain strengthen with the greater activity between neurons (Citri & Malenka, 2007). Therefore, understanding how to increase synaptic plasticity of CSC could increase the efficacy of the Purkinje circuit and thereby improve motor coordination, function and cognition. Disabilities like cerebral palsy, muscular dystrophy, multiple sclerosis, Parkinson’s disease, and others all impact motor function/coordination (WebAIM: Motor Disabilities - Types of Motor Disabilities, 2012). Research around CSCs provides a basis for possible treatments to motor disorders, and any other neurological dysfunction impacted by the Purkinje circuit.   

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[+] Other Work By Chandler Fanning