Do we only use 10% of our brain?

Devan Mair

Pause a moment. Guess how much of your brain is being used to allow you to read these words. How much of your brain would light up if you could see how much was active right now?

The brain isn’t a big messy ball of nerve cells that just do everything. Different areas of the brain do different things. For example the frontal lobe, at the front of the brain, helps us make decisions, along with lots of other things. The parietal lobe on the rear of the brain helps you feel pain and temperature. The temporal lobe – on the sides of the brain – has a role in memory. The occipital lobe found at the back of the brain helps with vision. Think about the brain activities involved in reading this article. You will have used your frontal lobe to make a decision that this blog was interesting to you. You will have used your temporal lobe when remembering how to operate your electronic device to scroll down the page. You are using your occipital lobe to receive messages from your eyes as you look at the words you read. Each lobe is important! But you don’t need to use them all at the exact same time. Depending on what your brain is doing, different regions are active. 

Nerves are the busiest and hungriest type of cell. They munch up the greatest amount of energy (also known as ATP) compared to any other cell in the body. Even when they aren’t sending messages around the body, they still use up lots of energy when they are relaxing. This relaxed state is called a resting potential. When a nerve sends a message, something called an action potential occurs. While resting potentials use up lots of ATP, action potentials use up even more! If all 86 billion of the nerves in your brain were just resting, they would still require lots of energy. But if every nerve was active with an action potential, if you were ‘using 100% of your brain’, then you would use up a ridiculous amount of energy – in fact, too much for your body to handle. Your body would never be able get hold of and redirect enough ATP to the brain. So using all of your brain power at one time isn’t possible!

So firstly, we don’t need to use all our brain all at once because areas of the brain do different things. And secondly, even if you had a magic pill that made you use 100% of your brain, you wouldn’t be able to provide the energy needed for all those nerves to be active. People often say we use only 10% of the brain. This is a bit wrong. We use between 1 and 16% of the brain at any one time. But a second later, you might be using completely different areas because you might be doing a different activity. It’s not that useful to think of how much of our brain we are using at one time – because the areas we use change really fast.

If you use special scanners to look at a brain’s activity, you can ask the brain-owner to use their brain in a certain way and check that the correct area lights up. For example, tell them to walk on the spot and the motor cortex – in the middle of the outer surface of the brain –  will light up as this enables movement. If the scanners show that an area isn’t lighting up when it should, your brain may have had some damage, maybe due to a stroke – when the blood can’t get to a region of the brain – or due to a disease like Alzheimer’s when nerve cells die. 

Hopefully you can now easily explain why you can’t use all of your brain at once!