June 16, 2024

The idea that we use only 10% of our brains has become a commonly heard “fun fact,” even becoming engrained in pop culture such as through the 2014 film “Lucy” that explored what could happen if humans could tap into the rest of their brainpower.

This would be an interesting movie concept — that is, if we did not already use more than 10% of our brains. Dr. Stephen Runyan, associate professor of biology, said that brain activity measured through modern brain scans displays that the 10% idea is not the case.

One measurement technique, the PET scan, uses radioactive glucose to illustrate blood flow in the brain. Runyan said that if a patient looked at a picture on the wall, for example, the scan would display brain activity in the visual cortex of the brain.

“The more active regions attract more of this radioactive glucose,” Runyan said. “So you watch the back part of the brain get all lit up — you have probably seen those pictures of the rainbow-colored brain. So that region of the brain becomes more active for vision.”

Runyan said that during certain activities, scans can indicate which areas of the brain become more or less active. However, even areas of the brain that are less necessary for an activity are not simply unused as the 10% theory suggests. Take the same example of the patient looking at a picture. When the patient is no longer looking at the picture, activity slows in the visual areas of the brain, but that does not mean they are not active at all.

“There are ideas that you are only using a certain amount of your brain because if your eyes are closed, you’re not using your visual cortex nearly as much as if your eyes are open,” Runyan said. “But if you just think about baseline — you are sitting there and doing nothing — your brain is still super active because there is a lot going on that we are never consciously aware of.”

In fact, portions of the brain such as the brain stem are constantly active, which regulates involuntary activities such as breathing, hormones and body temperature.

The brain is a complex organ, and the 10% theory simplifies brain usage beyond a point that is possible, Runyan said.

“As we’re thinking about stuff or working on problems or reading, or experiencing emotional experiences, all sorts of different parts of our brain are involved in those experiences,” Runyan said. “So to say at any given time that you are using 85% of your brain or 25% of your brain, I would have no easy way of measuring that or putting a number on it. But certainly [in] different regions of the brain, the activity fluctuates depending on the specific activity we are doing.”

Even when we sleep, brain activity does not slow as much as is perhaps expected. During the deep sleep phase of sleep, electrical activity in the brain does slow significantly so that the brain can recover.

However, during rapid eye movement (REM) sleep, for example, the brain is extremely active
“[During] those periods of sleep, some regions of your brain are more active than when you are alert and awake, just depending on what you are doing,” Runyan said. “A lot of the emotional parts of the brain become very active during REM sleep.”

Despite evidence in modern neuroscience indicating that brain scans do not support the 10% theory, the theory continues to persist and has done so for decades.

“This myth arose as early as 1907, propagated by multiple sources advocating the power of self-improvement and tapping into each person’s unrealized latent abilities,” according to an article in the National Library of Medicine.

Jade Adams, senior biomedical science major, credits the endurance of this myth to our desire to explain the complexity of the brain.

“I think there are myths about how we only use a small portion of our brain because there are so many different components to the anatomy of the brain to the point where it seems humanly impossible to be able to use every distinct portion of our brains,” Adams said.

Runyan said that he thinks that the idea continues because it popularizes the idea that we have not reached our full potential and that we could do more with our brain capacity.

“Otherwise, if we’re only able to use 10% of our brain, then what’s the point in saying that?” Runyan said. “It would just be like a fact. But if it’s to encourage you like, ‘Hey, there’s more here you could be using,’ then I could see how that phrase could gain traction.”

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