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by Melody Clearwater

Created on: October 22, 2010   Last Updated: October 29, 2010

The idea that humans use only ten percent of their brains is just a myth.  This myth has several possible origins and no scientific backing to support it.  In fact, the idea that humans use only ten percent of their brains is almost laughable because the brain is responsible for so much more than “thinking”.  Scientific research has shown the brain to be responsible for many different functions throughout the human body.  These involve functions that we can control, such as walking or running, as well as functions we cannot control, such as heartbeat.

In order to refute this myth, one must first have an understanding of the human brain.  Our brain is the center of the human nervous system.  The brain rests suspended in cerebral fluid within the cranium of the human skull.  The brain is attached to the spinal cord, which in turn is attached to the thousands of nerves that spread throughout the body.  These nerves continuously send sensory information to the brain, such as weather an object the person is touching is hot or cold, rough or smooth, etc.  In turn, the brain can command the nerves to send information to the muscles for movement.

The human brain can anatomically be divided into different regions.  The brain can be divided into the left and right hemispheres, which are then connected by a bundle of nervous tissue called the corpus callosum.  The left hemisphere controls sensory information and movement on the right side of the brain, and the right hemisphere controls sensory information and movement on the left side of the brain.  The cerebral cortex is the wrinkled layer of tissue that covers the forebrain.  The brainstem, which is located at the base of the brain, controls automatic processes such as breathing and heart rate.  The cerebellum is located above the brain stem and is responsible for balance and coordination of the human body.

The human cerebral cortex can also be divided into specific functional areas.  For instance the frontal lobe, which is located at the front of the brain, is responsible for recognizing consequences from current actions and for understanding social norms.  The parietal lobe, located on the top of the brain, plays important roles in integrating sensory information from various parts of the body, knowledge of numbers and their relations, and in the manipulation of objects.  The occipital lobe is responsible for visual sensory information, auditory information is sent to the temporal lobe, and various association areas spread throughout the cortex of the brain are responsible for thought and decision making.

Now that we have a basic understanding of the anatomy of the human brain and its functions, we can begin to understand why the 10% brain myth is really just a myth.  The “10% brain myth” is a highly perpetuated myth that has been continuously misattributed to geniuses, such as Albert Einstein, as well as psychics.  There are many possible origins of this myth.  One such origin possibly occurred when people misunderstood a statement from American writer, Lowell Thomas, when he stated that “the average person develops only ten percent of his latent mental ability.  Another possible origin is from the public misrepresentation of research results during the late 19th century or the early 20th century.  During that time period, it was announced that only ten percent of neurons were firing at one time.

In fact, neuroscientist Barry Beyerstein points out seven rebuttals for this myth:

1)      If 90% of the brain is unused, then chances are that a brain injury would cause no loss of function.  However, there is almost no area in the brain that can be damaged without loss of function.  A popular story for this case is the sad tale of Phineas Gage, who was remembered for his survival of a terrible accident during the 19th century.  Pineas Gage was a railroad construction foreman who had a large iron rod driven through his head, destroying much of his brain’s left frontal lobe.  Although he survived the accident, his personality and behavior changed dramatically and he could no longer work as a foreman.

2)      As humans evolve, natural selection occurs.  As the brain is costly to the body in terms of oxygen consumption and energy, humans with smaller brains would survive over humans with larger brains.  The humans that do not use 90% of their brains would be “weeded out.”  In fact, the human brain has grown in size during the course of evolution.  Throughout the course of evolution, the human brain has been marked by a steady increase of encephalization, which is an increase in brain size to body size ratio.

3)      Brain imaging technologies (such as PET/CT scanning) have allowed us to visualize activity occurring within the brain.  Even in sleep, all areas of the brain show activity.  In PET/CT scanning, a small amount of radioactive material is injected into the body, which eventually accumulates in the brain and causes areas to “light up” on a screen.  If most of the brain was inactive, then there will be large dark areas on the image of the brain during a PET/CT scan.

4)      As we have discussed before, the brain does not act as a single mass.  Instead, it contains distinct regions for information processing.  For decades, humans have researched brain mapping and no functionless areas have been found.

5)      In single-unit recording, a tiny electrode is inserted into the brain and the activity of a single brain cell is monitored.  If 90% of the cells are unused, then this technique would be so difficult that it would not be used.

6)      Another scientific technique studies the uptake of 2-deoxyglucose molecules by the brain.  If 90% of the cells are inactive, then blank areas would show up on the results.  No such result has ever occurred.

7)      Unused brain cells have a tendency to degenerate.  This is because when cells loose their function (or “die”), the body will recycle the cell and use its proteins and amino acids for the growth of other cells.  Autopsies of healthy adult brains do not show large-scale degeneration.

There is much scientific evidence that supports the fact that humans use 100% of their brains.  The human brain is not only the source of cognitive function, but it is also the source of many different functions ranging from the unconscious control of breathing to the conscious control of body movement.  According to Barry Gordon at Johns Hopkins School of Medicine in Baltimore, the myth’s durability stems from people’s conceptions about their own brains.  They see their own shortcomings as evidence of the existence of untapped gray matter.  As a matter of fact, there is no scientific evidence that supports the idea that humans only use 10% of their brains.  What is true is that when a person is simply at rest and thinking, that person may only be using ten percent of his/her brain at that given time.  However, during the course of an entire day, that person will probably use close to 100% of his/her brain.  The misrepresentation of scientific research has been far too long perpetuated and needs to be brought to common knowledge that humans, in fact, use 100% of their brains.

Resources

Wikipedia, “10% brain myth”.
Wikipedia, “Human Brain”.
Wikipedia, “Phineas Gage”.
Scientific American “Do People Only Use 10 Percent of Their Brains?”
radiologyinfo.org
Snopes.com, “The Ten-Percent Brain Myth”.

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