Not every cell in the brain fires action potentials. Star-shaped astrocytes outnumber neurons in many regions and perform essential support work. They regulate the extracellular environment, supply neurons with metabolic substrates, and help form the blood-brain barrier.

Processes from a single astrocyte can contact thousands of synapses, sensing activity and adjusting local blood flow and ion concentrations. When neurons are damaged, astrocytes react by changing shape and releasing signaling molecules that can either protect or, in excess, contribute to inflammation.

Recent work shows astrocytes also participate in synaptic plasticity and information processing through calcium signaling and gliotransmitter release. Their dual role as caretakers and active partners makes them central to both healthy brain function and neurological disease.

• Star-shaped glial support cells
• Maintain extracellular ion and transmitter balance
• Contribute to the blood-brain barrier
• Respond to injury and modulate synapses