Brain Myths: How Much of Our Brain Do We Use?

“I have been told that we only use 10% of our brain's capacity. Not sure all the reasons why we cannot access the other 90%. I want to. I wouldn't mind having a better memory!”

There are differing opinions on this. Some say it's true and it's the result of a built-in redundancy. Not available until something goes wrong.

I personally am in the “I don't think so” school and there are a number of lines to evidence to support me on this. I suggest our brain is 100% active – with more brain activity in some areas at some times for some life activities.

If you look at brain scans, there are no “unused” areas of blackness.

And the brain doesn't work like we used to think — in a mechanistic, linear way of “neuron A connects to neuron B connects to neuron C”. With that model, you can imagine that there might be a lot of unused real estate.

Instead, the brain works in non-linear networks of spreading activity – some specific areas of the brain might have a lot of connected neurons that contribute to a certain network – for example, memory for what you heard — but other areas of the brain will also have neurons linked into these memories. And neurons participate in more than one network, so any particular brain activity is involving the whole sha-bang to some degree.

Also — brain cell connections atrophy when they aren't used, so if you were carrying around a whack of unused brain cells, just in case of disaster, they would wither on the vine, so to speak. (Wow, is that a Case of Mixed Metaphors??)

And that last principle takes us to the next part of the question – how can I use my brain better?

Building Your Brain

There are ways to sharpen your memory or any other brain function – one being to use it as much as possible. When you do things (or even try or imagine yourself doing them), your brain starts to allocate resources to them and you get better and better at them.

There are some lovely studies demonstrating this. One is an interesting project that looked at the brains of London cabbies. When they looked at scans of their brain activity related to identifying London streets, it used much more brain real estate than in non-cabbies.

Another is a technique that is used to help stroke survivors regain functioning of limbs that were unusable due to brain damage (it's called “constraint-induced movement therapy” – see the links at the end of the article). Imagine your left arm just isn't working. Useless little thing hanging there, maybe with fingers all curled up and hard to straighten.

Now imagine that your therapist has restricted the movement of your right arm – the useful one. A bit of panic may start to rise, but for the next 5-6 hours you practice a number of activities, using only your left arm! Initially you have trouble of course, but over the course of a couple weeks, you can see and feel visible improvement. Your arm is starting to work again!

And that's because your brain is re-mapping to do what you are asking it to do. It's not a matter of calling in unused cells — none of us stay healthy without a purpose, not even our cells – it's an actual re-mapping of connections, maybe some recovery of injured neurons.

Principle: Our brain works as a whole to get done what we absolutely, positively, need to get done.

Taxi drivers needed to know a gazillion streets well and their brain activity expanded to  accommodate it. Stroke survivors with restricted usable limbs had to find a way to use their injured side and their brain accommodated to permit it.


Of course, another way to improve your memory is to do some neurofeedback work. (Sorry – couldn't resist).

Maybe of even more impact is what this tells us about the importance of our daily thoughts and feelings and experiences. Practice what you want, not what you want to move away from, because your brain is changing to create what you do the most. Let's talk some more about that in another post, it's so important.

If you like the idea of looking at different Brain Myths, let me know and we can do some more 😉
If you have questions about whether something you think you know is true (or just can't believe could be true), ask  away! I'd love to hear your questions.

For more on examples of training your brain without equipment, explore the London cabbies study
and learn more about Constraint-Induced Movement Therapy at the website of Edward Taub, the researcher who created the technique and first demonstrated its effectiveness.

If you're hungry for more on the science of CI therapy, try this paper that shows the changes in the brain after training.