Investigate Your Brilliant Brain to see how, along with the nerves of the spinal cord, it runs your nervous system. It’s like one big computer network with messages whizzing to and fro all the time – whenever you think, see, speak, feel hot or cold, or move – in fact when you sense or do anything at all. Those 100 billion neurons in your brain are busy, busy all the time processing information – no wonder it uses 20% of the body’s energy! And the good news for brainboxes is that bigger and heavier doesn’t always mean cleverer…!