Is it true we use only 10 percent of our brains?

You sometimes hear that we humans use only a small portion of our brains – the number 10% is frequently used. Or sometimes you hear that there’s a part of our brain that’s not used at all. Is either of these ideas true?

No. No one knows precisely where these modern-day myths got started, but they are untrue.

The human brain is an “expensive” organ in terms of our bodies’ energy use. It’s made up of about a hundred million nerve cells. Each of these nerve cells is a like a tiny battery. Charging and recharging these batteries uses up a lot of energy. As a result, the brain consumes far more energy than you might expect based on its modest three-pound weight. If all those nerve cells weren’t put to some use, they wouldn’t be kept over the long haul.

After a few million years, those nerve cells in the brain would have evolved out of existence. From an evolutionary perspective, there is some – but not much – waste to what our bodies do. It’s safe to say that most of the brain is used.

Moreover, imaging studies that map brain activity – like PET scans and fMRI – show that brain activity is spread throughout the brain. These techniques show very precise localization of brain functions. In other words, they show what parts of the brain are active when you sleep, when you listen to music, or when you’re doing a difficult math problem. It does seem that at any one time only a portion of the brain is in active use. But the entire brain is used at one time or another.

Some of our strongest emotions happen in the most ancient regions of our brain. Other parts of the brain are used for vision and problem solving.

It seems that all of the brain (or at least most) is used as you become engaged in complex thought patterns or activities.

In that way, your brain is like your muscles. You don’t use all your muscles at once, but in the course of your daily life you do use all of your muscles part of the time. Likewise, you don’t use all your brain at once, but over the course of days the entire brain does get used.

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