What is a neuron?
A neuron is a nerve cell: a specialized cell that sends electrical and chemical signals to other cells, carrying every thought, feeling and movement.
Think of neurons as a vast network of telephone lines. Each one receives calls through short branches, then sends a message down a long cable to the next line. Billions of them, connected, make up your brain's communication system.
Why it matters for aging
Your brain has around 86 billion neurons. Because most don't divide or get replaced, they must last for decades, which makes them especially vulnerable to slow damage, such as worn-out mitochondria or misfolded proteins building up inside.
Neurons are also extremely energy-hungry: sending signals constantly requires a steady supply of ATP. That's one reason sleep, blood sugar balance and healthy mitochondria matter so much for how clearly you think.
A common myth
You're born with all the neurons you'll ever have, and they only die off with age.
Most neurons do last a lifetime, but the connections between them keep changing throughout life. In animals, and possibly in humans, a few brain regions such as the hippocampus may keep making new neurons in adulthood.
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Updated Nov 9, 2026 · All terms