The Quanta Podcast Astrocytes Might Be in Charge of the Brain
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Mar 17, 2026 Ingrid Wickelgren, science journalist who covered astrocytes’ surprising roles. She explores how astrocytes envelop synapses, show calcium waves, respond to norepinephrine, and can influence behaviors from sleepiness to ‘giving up.’ The conversation highlights imaging breakthroughs, causal experiments in animals, and implications for mood and brain-state control.
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Astrocytes Sit At Synapses And Match Neuron Numbers
- Astrocytes are as numerous as neurons and were long thought to be mere support cells that buffer ions and clean up waste.
- Ingrid Wickelgren explains a single astrocyte can envelop hundreds of thousands of synapses, placing it at the junctions where neurons communicate.
The Lab Moment Astrocyte Signaling Was First Seen
- Stephen Smith's lab used a novel microscope to image calcium and found astrocytes 'lighting up' in culture when stimulated with glutamate.
- Steve Finkbeiner shouted for his advisor because astrocytes showed calcium waves, a previously unseen signaling phenomenon.
Startle Responses Reveal Astrocyte Activation Mechanism
- Imaging in awake animals showed astrocyte calcium waves are reliably triggered by sudden startle stimuli like a puff of air or abrupt treadmill movement.
- Those startle-triggered responses implicated norepinephrine as the neuromodulatory trigger for astrocyte activation.
