Dr. Reneh Karamians

Five Facts About the Brain Everyone Should know

Dr. Reneh Karamians, Psy.D.

As a student of Neuropsychology, I get asked a lot questions about the human brain. One of the most popular is “Do humans really only use 10 percent of their brain?”. Well, I thought I would take this opportunity to address some of these questions. So, here we are in no particular order.

1) Do people really only use 10 Percent of their brain?

I’ll be honest. I’m not even sure what this questions means. But I have tried to make some sense of it and I have been able to come up with two answers. The first addresses the brain’s mass and the second the brain’s capacity to store information. So, do people only use 10% of their brains? If any one individual was forced to live with 90% of their brain mass removed, they would most certainly not survive since most of the lower brain regions that control heat rate, breathing and other homeostatic functions would be gone. So, the answer in this case is, no. A person cannot live by using only 10% of their brain mass.

On the other hand, “10%” could suggest that humans only use 10% of their brain’s capacity to store information. This makes things a bit more complicated. The answer to this second question is, we really can’t know. Currently, there is no known imaging procedure which measures the brains capacity to store information. The closest medical tool we have for this is, you guessed it, IQ tests. Still, even with IQ tests we can only measure how much information is stored in short-term and long-term memory at the time of testing. We cannot measure what “percentage” of the brain is being used to store the given information. So if you’re one of those people who constantly says things like “you know, we only use 10% of our brain right?” Stop it! Please!

2) Are some people really left-brained while others are right-brained?

Yes! For most right-handed people, the brain is “typically lateralized”. This means that the left portions of their brain (the left temporal and parietal lobes) are involved in verbal tasks, while the right portions (the right temporal and parietal lobes) are involved in visual tasks and representation of numbers, faces and places. In certain individuals the left side of the brain tends to develop more so than the right, while in others the right side tends to dominate. Left-brained people tend to do well with verbal tasks. These individuals are often writers and scientists. Right-brained people, on the other hand, tend to be more artistic and become musicians or, I don’t know… graphic designers, lets say.

Now, you may have noticed that I started by saying that the above is all true for “most right-handed people”. This is because about 25% of left-handed people are “atypically lateralized” which means the right side is more verbal while the left side is more creative. This percentage increases when one of the parents of the left-handed individual is also left-handed (is your mom or dad left-handed, lefty? Hmm?). So think about your job, your hobbies and the classes you enjoyed while in school, and maybe you can figure out if you are left-brained or right-brained!

3) Where in the brain are memories stored?

This is a popular question. All your memories start by entering your “working memory”, a function of the “frontal lobe” or the outer front portion of your brain. When any kind of information, be it visual or verbal, is acquired within working memory we call this “registration” in clinical terms. After “rehearsal”, (practice or studying repeatedly) the information moves from working memory to the hippocampus (see figure 1, see the green parts? Yup that’s what it looks like). When you try to remember something, what we refer to as “recall” in medical terms, the frontal lobe accesses the information in the hippocampus and brings it into conscious thought. So that is how you remember.

Another fact worth mentioning is that, in advanced Alzheimer’s disease, imaging studies tend to show shrinking of the hippocampus (both sides). In other forms of dementia, such as “frontotemporal” dementia, we see the frontal lobe shrinking first. Which means the information is still usually alive and well within the hippocampus (for a while anyway), but the frontal lobe can’t pull it out anymore! Smart neuropsychologists have ways of determining, with some small level of confidence, if the dementia is Alzheimer’s type, or some other form. But, typically, and very sadly, it’s usually Alzheimer’s since 75% of dementia cases are Alzheimer’s type.

Figure 1

4) Can the brain feel pain?

No. Other parts of the body have what we call “pain receptors” which are specialized neurons that send pain signals to the brain and spinal cord and thus pain is perceived. However, the brain has no pain receptors so lesions in the brain do not cause pain. Interestingly, this has allowed brain surgeons to permit patients to remain conscious during brain surgery and have electrically stimulated certain parts of the brain to see how the patient will react. One popular anecdote claims that during such a procedure, a patient reported smelling oranges when a specific portion of the brain was stimulated. So, then why do we get headaches? Well, headaches are typically a vascular issue and this is a whole other topic worthy of a separate discussion. But I won’t get into that now.

5) How many calories does the human brain burn in a day?

This one is easy. The brain consumes about 20% of the caloric energy you consume. So, if you’re trying to burn calories, you may benefit from taking a book with you to the gym and try reading or studying while on the ol’ elliptical or bike!