How does the brain work?

86 billion neurons, 100 trillion connections and about 20 watts. The cerebrum's two hemispheres each have frontal, parietal, temporal and occipital lobes, wrapped in a folded cortex only 2 to 4 mm thick. Under the back sits the cerebellum, and the brainstem joins it all to the spinal cord.

Read how it works: How does the brain work? · The history of the brain · More boxes on Glassbox

Chapters in this interactive model

1. Inside the human brain: Two wrinkled halves, four lobes each, and a busy core.
2. A neuron fires: Tiny batteries, a trigger point, and a spike that races down a wire.
3. Where neurons meet: A spark becomes a chemical, crosses a gap, and becomes a spark again.
4. Who does what: Areas with jobs, a body map with giant hands, and no silent 90%.
5. How memories are made: A seahorse-shaped sorter by day, a replay machine by night.
6. Fuel, flow and what goes wrong: A hungry organ, a guarded supply line, and why minutes matter.