Our understanding of each brain cell's role isn’t complete without recognizing the diverse and dynamic nature of astrocytes, a crucial type of support cell in the nervous system. While neurons often steal the spotlight for their role in transmitting information, the health and functionality of the brain depend heavily on many other cells working behind the scenes. Among these, astrocytes stand out due to their abundance and multifaceted responsibilities. These star-shaped cells are instrumental not only in shaping neural circuits and facilitating information processing but also in providing essential nutrients and metabolic support to neurons. Interestingly, individual astrocytes are not static; they can adopt new functions over their lifespan, adapting to the changing needs of the brain. This means that at any given moment, astrocytes in one part of the brain may behave very differently from those in another region, highlighting their incredible versatility.
Recently, neuroscientists from MIT have published a groundbreaking atlas that maps the diversity of astrocytes across different regions of the brain and through various stages of development. Using this atlas, researchers can now visualize how astrocyte populations are tailored to specific brain areas in both mice and marmosets—two prominent animal models in neuroscience. Moreover, the atlas reveals how these populations evolve as the brain matures, ages, and undergoes structural changes. This resource was detailed in a widely accessible study published on November 20th in the journal Neuron, led by Professor Guoping Feng from MIT. Support for the research was provided by the Hock E. Tan and K. Lisa Yang Center for Autism Research, part of MIT’s Yang Tan Collective, as well as the National Institutes of Health’s BRAIN Initiative.
Feng emphasizes the importance of exploring the roles of non-neuronal cells in both health and disease states. For many years, astrocytes were dismissed as mere supporting players in brain function. However, recent research indicates they are vital in processes such as brain development, maintaining neural stability, and possibly contributing to psychiatric and neurodegenerative conditions when their function goes awry. Despite these advances, Feng notes that our knowledge of astrocytes, especially during early development, is still limited compared to what we know about neurons.
This research team, including former graduate student Margaret Schroeder, sought to understand astrocyte diversity across three critical axes: where in the brain they are located (space), how they change over the lifespan (time), and how this varies across different species (species). It is already known from previous studies—some done in collaboration with Harvard’s Steve McCarroll—that adult brains have region-specific types of astrocytes. But a key question was: When does this regional patterning begin during development?
To explore this, Schroeder and her colleagues collected brain cells from mice and marmosets at six distinct life stages, from embryonic days to old age. They sampled four key brain regions in each animal: the prefrontal cortex, motor cortex, striatum, and thalamus. Using advanced molecular analysis techniques, they examined the genetic activity within these cells by profiling their transcriptomes—that is, the complete set of messenger RNA (mRNA) molecules produced by each cell. This approach provides valuable insights into which genes are active and thus, what functions the cells are performing.
Analyzing approximately 1.4 million brain cells, their team zoomed in on astrocytes to understand how their gene expression patterns vary over the course of development. They found consistent regional differences at every stage of life—from before birth to old age. In each brain region, astrocytes exhibited similar gene expression profiles that set them apart from astrocytes in other regions. These differences were also reflected in the physical shapes of astrocytes, observed through high-resolution imaging techniques such as expansion microscopy, pioneered by McGovern Institute collaborator Edward Boyden.
One surprising discovery was that astrocytes already begin to show regional specialization during late embryonic stages. However, these profiles change markedly after birth and continue to evolve through early adolescence—a period characterized by rapid brain rewiring as animals learn to navigate their environment. Schroeder suggests that these changes are driven by the developing neural circuits—astrocytes may adapt their genetic programs in response to nearby neurons or even help steer the formation and refinement of local neural networks.
Both mouse and marmoset brains displayed regional astrocyte diversity and developmental shifts. Yet, when comparing the specific genes underlying these cell populations across species, the team noted differences. Schroeder emphasizes caution here: these variations remind us to carefully consider species-specific details when translating findings from animal models to humans. Nonetheless, the new atlas provides a powerful tool for assessing how astrocyte functions relate across different species.
Beyond mapping astrocytes, Feng’s team intends to focus on how genes linked to various diseases impact these support cells throughout development. He envisions their gene expression data as a roadmap for predicting how astrocytes interact with neurons and how these interactions may change in disease states or during brain maturation. The team is also encouraging other researchers to explore the extensive dataset they have generated. Although the primary focus was on astrocytes, the transcriptomic analysis included many other brain cell types, offering a treasure trove of information to decipher when and where specific genes are active in the brain. This open resource aims to propel future research into understanding the complex cellular choreography that underpins healthy brain function—and what goes wrong during disease.
And here's where it gets controversial… should we be more cautious in interpreting astrocyte functions across different species, given their apparent differences? Are these differences a challenge or an opportunity for developing more precise models of human brain disorders? What do you think—are astrocytes truly the unsung heroes of the brain or just supporting characters waiting in the wings? Share your thoughts in the comments below!
