The ‘silent’ brain cells that shape our behaviour, memory and health
Article Date: 2025-06-18
Article URL: https://www.nature.com/articles/d41586-025-03912-w
Article Image: Image
Summary
For decades neuroscientists focused mainly on neurons, treating other brain cells as mere support. This article reviews growing evidence that astrocytes — star-shaped glial cells once deemed electrically silent — actively shape brain function. New molecular tools and imaging have revealed that astrocytes use calcium signalling to regulate blood flow, clear neurotransmitters, control synaptic environments and release signalling molecules that change how neurons behave. They reach enormous numbers of synapses (up to two million per astrocyte in humans) and come in distinct types across brain regions.
Recent studies show astrocytes are crucial for circadian rhythms (by rhythmically handling GABA and glutamate in the suprachiasmatic nucleus), for encoding spatial reward information, and for stabilising and recalling fear-primed memories. Astrocyte signals are slower than neuronal spikes — often spanning seconds to hours — which makes them well suited to bridge learning and long-term memory processes. As a result, researchers are reassessing neurological and psychiatric diseases for astrocytic contributions.
Key Points
- Astrocytes were long dismissed as passive support but are now recognised as active modulators of neuronal computation.
- They use calcium-based signalling (slower than neuronal spikes) to sense and change the synaptic environment, affecting neuron firing and circuit states.
- Astrocytes regulate blood flow, clear neurotransmitters (notably glutamate), control ion balance and recycle metabolic building blocks for neurons.
- Individual astrocytes contact vast numbers of synapses (up to ~2 million in humans) and differ by brain region and function.
- Experimental advances (genetic tools, fluorescent probes, microscopy) have linked astrocytes to circadian clock regulation, spatial reward encoding, and memory stabilisation and recall.
- Because astrocyte signalling is slower and longer-lasting, they are well placed to bridge short-term neuronal events and longer-term changes like memory consolidation.
- Understanding astrocytes reshapes how we think about brain disorders — diseases long blamed solely on neurons may involve astrocytic dysfunction.
Context and Relevance
This article highlights a major shift in neuroscience: the move from a neuron-centric view to recognising glial cells as central players. The findings intersect with several hot areas — neurodegeneration, psychiatric illness, sleep/circadian biology and memory research — and rely on recent technical advances (live calcium imaging, molecular genetics and high-resolution microscopy). For researchers and clinicians, the work suggests new therapeutic targets; for technologists, it underscores the need for tools that read and manipulate non-neuronal signalling.
Why should I read this?
Short version: these ‘silent’ cells aren’t silent. They quietly shape how we remember, feel and sleep — and they might be behind diseases we blamed on neurons alone. If you care about how the brain actually works (and who doesn’t?), this is a neat, fast update on a field that’s gone from fringe to front-page. Reading it saves you digging through the specialist papers yourself.