Beyond Neurons: The Rise of Glial Cells in Neuroscience

Written by: Emma Reid

Edited by: Fahad Hassan Shah and Nadia Hall

(Photo by dhproductions from Unsplash. https://unsplash.com/photos/person-holding-round-clear-container-tGYrlchfObE)

Introduction

For decades, neurons have dominated the field of neuroscience. They have been at the center of it all: neurodegeneration research, medicines, clinical trials, even daily tasks to strengthen the brain. But what if a new player has started to emerge in the game?

Glial cells have been background noise for quite some time. Often these cells are seen as nothing more than support cells, as they do not transmit electrical signals of their own. But recent research shows that glial cells may play active roles in neural processes involving learning, memory, and even immunity, making them more than just side characters in your brain.

Meet the Central Nervous System’s Glia*

Astrocytes: Though often seen as biological scaffolding for the nervous system, astrocytes do more than just hold up neurons. They play an important part in maintaining the blood-brain barrier, which is the wall that separates your blood from your brain in order to stop harmful molecules from traveling into your nervous system. They also provide fuel (think glycogen and lactate) to neurons to keep them going, and they even regulate the communication between neurons with their very own neurotransmitters (Kim et al, 2026). 

Oligodendrocytes: These trusty cells stick close to neurons in the nervous system to wrap them in a fatty membrane called myelin. Myelin allows signals to travel down the axon—the main signal highway in neurons—quickly, up to 225 miles per hour (or about 100 m/s) (Students of PSY 3031 & Olman, 2022). Without them, signals in the nervous system would travel very slowly, which would not make it very easy to react to the outside world. Oligodendrocytes also help myelin change over time to make learning from new experiences easier and faster ("Oligodendrocytes," n.d.).

Microglia: These are part of the brain’s first line of defense against infectious pathogens, such as viruses and harmful bacteria. There are only a small number of them in the brain, but they are mighty. They also regulate neurons during development by pruning away excess or unnecessary synapses in order to generate stronger, healthier ones for adulthood (Shimizu & Prinz, 2025). 

*This section pertains to the glial cells found only in the central nervous system (CNS), which solely comprises the brain and spinal cord. Different types of glial cells are found in the peripheral nervous system (PNS), which comprises sensory and motor neurons. Glial cells in the CNS and PNS have similar functions, but differing anatomies, making them unique from each other. 

Image designed through BioRender. Astrocytes (red) maintain the blood-brain barrier and support the neuron (purple). Oligodendrocytes (green) wrap around the neuron’s axon to increase the speed of electrical signals. Microglia (yellow) help fight off pathogens that may threaten the neuron. 

We’re All in This Together

Oligodendrocytes, astrocytes, and microglia all work in tandem to regulate the brain and its daily functions. They make sure the central nervous system (CNS) is in a constant state of equilibrium, or homeostasis. Homeostasis is a vital element in maintaining brain health because it keeps the environment stable for optimal performance. If the body falls outside of homeostasis, then it can become difficult, or even impossible, for normal processes to function properly. 

In addition, glial cells help the brain adapt and learn from new experiences quickly through synaptic plasticity. Synaptic plasticity is a unique property of the brain wherein synapses can permanently change to become stronger or weaker (Appelbaum et al., 2023). Stronger synapses strengthen new learning patterns, whereas weaker synapses make the brain forget them. It is like when you learn a new language, but then slowly forget it over time if you rarely use it. 

Overall, glial cells are an important part of regulating our body. While they do support neurons, they are also directly responsible for the health and growth of our nervous system. They maintain a stable environment for neurons to thrive in, while also promoting new learning and behavioral patterns in our brain.

Why Does This Shift in Research Matter?

Shifting the focus of scientific research from neurons to glial cells opens up new avenues for prevention and treatment plans for cognitive diseases, injuries, and mental disorders. Glial cells are not just side characters; they are active participants in exacerbating the symptoms and progression of these conditions. 

Neurodegenerative Diseases

One of the most prevalent topics of neuroscience research is the treatment of neurodegenerative diseases, such as Alzheimer’s disease. Microglia have been known to be one of the leading causal factors in the progression of Alzheimer’s, but the mechanism behind this relationship has been widely unknown. By carefully studying the stress responses of in vivo models, a group of researchers revealed that microglia secrete toxic lipids under stress, resulting in synapse loss and neuronal death similar to the pathology of Alzheimer’s (Flury et al., 2025). This direct link between microglia and Alzheimer’s could be isolated and targeted for future clinical trials, giving the opportunity for new possible treatments for Alzheimer’s disease in the future.

CNS Injuries

Glial cells can also be beneficial in treatment programs after brain injuries. Neurogenesis, or the growth of new neurons, is a process that continues throughout our lives. However, as we get older, production of new neurons slows. This makes the body less resilient when healing after brain and spinal cord injuries, leading to permanent disabilities and paralysis. However, oligodendrocytes and microglia have been shown to undergo transdifferentiation into mature neurons after CNS injuries (Casas-Tinto et al., 2025). This means that glial cells can help heal the body by not only promoting neurogenesis but also by becoming new neurons themselves. Therefore, targeted approaches to inducing glial cells to undergo this type of transdifferentiation could provide new beneficial treatments for those with previous and future CNS injuries.

Mental Health and Behavior

Due to the growing prevalence of mental disorders in the world, the neuroscience community has also focused heavily on studying the biology of these disorders. One major point of study has been clinical depression, which is a mental disorder that affects about 5.7% of adults globally and is growing (World Health Organization, 2023).

For over fifty years, the serotonin hypothesis has been widely accepted by the scientific community. Simply put, the serotonin hypothesis states that a lack of serotonin activity in the brain plays a causative role in the development of depression (Coppen, 1967). Following the publication of this hypothesis, many antidepressant medications were made to actively target these pathways—which we now know as modern-day selective serotonin reuptake inhibitors (SSRIs). However, SSRIs have been variable in their antidepressant response for those dealing with depression. Repeated clinical trials and studies have shown that there are both responders and non-responders to the drug, though the biological mechanisms behind these responses are still unknown (Boschloo et al., 2023). This variability in clinical responses to SSRIs limits medicinal treatment options for some individuals.

However, scientists are beginning to question the serotonin hypothesis, leading to new research on the physiological mechanisms behind depression. As the main source of communication between the brain and the body, it is no surprise that glial cells have been discovered to play a large role in this disorder.

Neuroinflammation, specifically glial cell-driven neuroinflammation, remains one of the key biological markers of depression. There are multiple reasons for neuroinflammation to occur in the brain, as it can originate in the CNS or the peripheral nervous system (PNS) of the body. One new hypothesis suggests that immune cells in the PNS release inflammatory factors under stress that infiltrate the blood-brain barrier and cause a dysregulation of homeostasis in the CNS, leading to neuroinflammation (Hassamal, 2023). Glial cells under stress also release inflammatory factors that disrupt synaptic plasticity and neurotransmitter pathways, which also play a crucial role in the onset and progression of depression.

Targeting glial cells, rather than neurotransmitters, with antidepressant medications provides alternate treatment options for individuals who are diagnosed with clinical depression and are unresponsive to typical SSRI medications. Scientists are already progressing with this novel idea by developing gene delivery approaches to specifically target astrocytes in the body (Zhou et al., 2025). By doing so, anti-inflammatory medications could be specifically delivered to astrocytes to decrease the inflammatory factors they release. With further research, it is possible that reducing these inflammatory factors could ultimately lessen patients’ depressive symptoms.

Conclusion 

Glial cells have been proven to affect multiple aspects of our body, including our biology, behavior, and cognition. Without them, neurons would have to fight off pathogens, maintain the blood-brain barrier, and send electrical signals all on their own, which would not allow them to do much else.

Neuroscience is undergoing a major shift. Moving from a neuron-centric viewpoint towards a more holistic approach in studying the nervous system has allowed scientists to achieve new advancements in health, medicine, and research. While neurons may do much of the heavy lifting in our brain, glial cells are essential for our nervous systems to function properly, stay healthy, and continue growing throughout our entire lives.

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References

Appelbaum, L. G., Shenasa, M. A., Stolz, L., & Tadin, D. (2023). Synaptic plasticity and mental health: Methods, challenges and opportunities. Neuropsychopharmacology, 48, 113–120. https://doi.org/10.1038/s41386-022-01370-w

Boschloo, L., Hieronymus, F., Lisinski, A., Cuijpers, P., & Eriksson, E. (2023). The complex clinical response to selective serotonin reuptake inhibitors in depression: A network perspective. Translational Psychiatry, 13(1), Article 19. https://doi.org/10.1038/s41398-022-02285-2

Casas-Tinto, S., Garcia-Guillen, N., & Losada-Perez, M. (2025). Adult neurogenesis through glial transdifferentiation in a CNS injury paradigm. eLife, 13, Article RP96890. https://doi.org/10.7554/eLife.96890

Coppen, A. (1967). The biochemistry of affective disorders. The British Journal of Psychiatry, 113(504), 1237–1264. https://doi.org/10.1192/bjp.113.504.1237

Depressive disorder (depression). (2023). World Health Organization. https://www.who.int/news-room/fact-sheets/detail/depression

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Kim, H. Y., Kim, S., Akaydin, A. N., et al. (2026). The rise of astrocytes: Are they guardians or troublemakers of the brain disorder? Experimental & Molecular Medicine, 58, 301–318. https://doi.org/10.1038/s12276-025-01627-6

Kenhub. (n.d.). Oligodendrocytes. https://www.kenhub.com/en/library/physiology/oligodendrocytes

Shimizu, T., & Prinz, M. (2025). Microglia across evolution: From conserved origins to functional divergence. Cellular & Molecular Immunology, 22, 1533–1548. https://doi.org/10.1038/s41423-025-01368-6

Students of PSY 3031, & Olman, C. (Ed.). (2022). Conduction velocity and myelin. In Introduction to sensation and perception. University of Minnesota Libraries Publishing. https://pressbooks.umn.edu/sensationandperception/chapter/conduction-velocity-and-myelin/

Zhou, H., et al. (2025). Efficient gene delivery admitted by small metabolites specifically targeting astrocytes in the mouse brain. Molecular Therapy, 33(3), 1166–1179. https://doi.org/10.1016/j.ymthe.2025.01.006