Human Body4 steps
The self-eating brain
A rabbit hole is a short chain of facts where each one hands you to the next. Start at the top and see where it leaves you.
- Your brain runs on less power than a fridge bulb.
Your brain runs on roughly 20 watts — about the draw of a dim light bulb — while operating some 86 billion neurons. Supercomputer simulations of even modest slices of brain…
It got that efficient the strange way: by deleting itself…
- You became you by deletion. Billions of connections cut.
A young child's brain contains far more synaptic connections than an adult's. Through childhood and adolescence the brain deletes the ones it rarely uses, a pruning that…
And the pruning shears belong to a very unexpected crew…
- Immune cells prune your brain. They eat synapses whole.
The pruning is done by microglia, the brain's resident immune cells, which physically engulf and digest synapses during development. Connections get marked for removal by…
But when fuel runs low, cells take recycling a step further…
- Starve a cell and it eats itself. Neurons included.
When a cell is starved it begins autophagy — literally 'self-eating' — breaking down its own components to survive, a process whose discovery won the 2016 Nobel Prize. In fasting…