Neurons have long dominated the spotlight in neuroscience, celebrated as the drivers of thought, movement, and memory. Yet, behind the scenes, a quieter, star-shaped group of cells—astrocytes—has been orchestrating much of the brain’s activity. In the latest Inside Salk Fall Issue, Salk Professor Nicola Allen explains how her research is revealing the central role these underappreciated cells play in brain health and disease.
Allen’s journey into science began in her school days in the UK, where simple experiments sparked a curiosity about the natural world. Initially drawn to veterinary medicine, she soon realized her passion lay not in applying treatments but in understanding the mechanisms behind them—a calling that ultimately led her to neuroscience and the study of astrocytes.
Her path took a pivotal turn during a short course at Cold Spring Harbor Laboratory, where she attended a lecture by the late Ben Barres. He demonstrated that neurons cannot form connections without the support of astrocytes. “I immediately thought, I need to do a postdoc with this person,” Allen recalls, a decision that would define her career and the emerging field of astrocyte research.
Historically, astrocytes and other glial cells were considered mere support for neurons, providing nutrients and structural scaffolding. Allen’s work, however, has revealed that astrocytes actively instruct neurons: guiding synapse formation, determining which connections are strengthened or eliminated, and dynamically shaping brain circuitry over time. Disruptions in this communication can contribute to neurodevelopmental and neurodegenerative disorders, positioning astrocytes as a promising therapeutic target.
This insight has profound implications for Alzheimer’s disease. Allen’s team has identified proteins secreted by astrocytes that stabilize synapses. In Alzheimer’s models, astrocytes produce fewer of these signals—sometimes before symptoms appear—highlighting the potential for early intervention. “We’re developing tools to deliver these proteins to create, repair, or remodel neuronal connections without directly altering neurons,” she explains, describing a novel approach to brain therapy.
Allen’s leadership extends beyond her lab. Recently promoted to full professor and awarded the Roger Guillemin Chair, she plays a central role in Salk’s Neuroimmunology Initiative and the Year of Alzheimer’s Disease Research. The initiative fosters collaboration across neuroscience, immunology, aging, and cancer, with Allen investigating how astrocytes interact with immune pathways to influence aging and disease. Her groundbreaking efforts were recognized with the 2024 NIH Director’s Pioneer Award for high-risk, high-reward science.
For Allen, Salk’s collaborative culture has been instrumental. “People are excited about new ideas, even outside the mainstream,” she says. The Institute’s structure encourages cross-disciplinary crosstalk, enabling her to explore bold questions about aging, memory, inflammation, and regeneration.
As the Fall 2025 Inside Salk issue highlights, the story of astrocytes exemplifies the power of exploring the unknown. Allen’s research not only reshapes our understanding of brain biology but also points toward innovative strategies for treating neurological disease. “We’re just beginning to fully appreciate the role of glia and astrocytes in the brain, and we’re already seeing so much potential for new therapeutic strategies. Exploring the unknown isn’t just bold—it’s essential,” she concludes.
