Some amazing brain facts

Let’s kick off this blog with some amazing but true information about the brain.

1. Your brain is about 60% fat! [1]  The fat makes up the electrical insulation around the nerve fibres (called axons).

2. Nerve impulses (spikes) travel through insulated axons at more than 400 km/h [2] (that’s more than 250 mph)!

3. If you lined up all the axons in your brain end-to-end they would go around the earth 4 times [3] (160,000 km or 100,000 miles)!

4. Your brain contains about 100,000,000,000 (100 billion) neurons and up to 1,000,000,000,000,000 (a quadrillion) connections between them!

5. Neurons are tiny. You can fit about 100 of them (arranged in a 10×10 square) inside the smallest dot you can see on a standard computer screen, like the dot here ⇒ .

6. Even so, if you laid all your neurons out side by side, they would make a line that stretched for 1000 km (600 miles)!

7. And even though your brain makes up only 2% of your body weight, it uses 20% of your blood and 20% of your oxygen [4]. By weight, it’s the hardest working part of your body (more than your muscles!).

8. Every time you learn something new (e.g. a new skill or even just a simple memory) it changes the structure of your brain.

9. Parts of your brain that you use a lot get more connected to the rest of your brain (and maybe bigger too), and parts that you don’t use lose connections. Use it or lose it!

10. Brain waves are real – they can be recorded using electrodes placed on your scalp. They change as your brain does different things.

11. When you dream, your brain disconnects from your body (your body is paralysed!) so that you don’t act out your dreamed actions.

12. It’s very hard to tickle yourself since your brain distinguishes between your own touch and somebody else’s.

13. The power your brain constantly uses is about 20 Watts – enough to power a light-bulb continuously for your entire life!


[1] CY Chang, DS Ke, JY Chen (2009). “Essential fatty acids and human brain”. Acta Neurol Taiwan.

[2] Hursh JB (1939). “Conduction velocity and diameter of nerve fibers”. American Journal of Physiology 127: 131–39.

[3] L Marner, JR Nyengaard, Y Tang, B Pakkenberg (2003). “Marked Loss of Myelinated Nerve Fibers in the Human Brain with Age”. Journal of Comparative Neurology 462:144–152.

[4] Hartline DK, Colman DR (2007). “Rapid conduction and the evolution of giant axons and myelinated fibers”. Curr. Biol. 17 (1).


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