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Do Humans Use 100% of Their Brains?

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Biology 202
2000 First Web Report
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Do Humans Use 100% of Their Brains?

PaShawnda Briley

Where did the persistent statement that humans use 10% of their brains originate and is it valid? It was first coined by William James, a philosopher and psychologist. Some professionals have even stated even lower percentages, like Margaret Mead saying that we use 6% of our brains (3). If this statement is true, it implies that humans could behave very differently and perhaps with greater thought and purpose. If the statement is a fallacy, it supports the brain equals behavior theory, such that the brain is not harboring unused capacities and behaviors.

The 1012 neurons in the brain have not all been researched for activity or not, but researchers have found no evidence for unused abilities or large, unused regions of the brain. Researchers know that humans do not use every region of their brain for every behavior, unless we are doing something so complex that it requires all of the brains capacities. At any given point in time, about 5% of the neurons are active, but over time and change of ones behavior, PET scans and fRMIs show that the vast majority of the brain is active (2). Perhaps this is an evolutionary adaptation: to conserve energy and prevent an electrical and chemical overload from all the neurons firing and inhibiting. The brain is about 3 pounds, using an inproportionate 20% of the bodys oxygen- rich blood, but is only 2% of the bodys total weight (3). The significance of the brain receiving so much of the bodys energy supply, reveals its ability to perform important functions. The heart and the lungs main function is to provide the brain with oxygenated blood, presumably because the brains will be performing essential neuronal activity relevant to the days behavior.

The highly specialized regions of the brain give some insight into the many functions that the brain is capable of doing. So the development of the brain into specific sections that have been researched to facilitate specific functions, provides evidence that these regions are active in a normal humans lifetime. The fact that the brain has a highly ordered procedure for developing, leads researchers to believe that each region of the brain is essential. In fact, researchers have found several regions to account for one function, to imply that the collaboration of several brain regions is sometimes necessary for normal functioning.

Other evidence against the statement that humans only use 10% of their brains. Of the 1012 neurons, humans possess extra neurons, but these neurons serve the purpose of repair when severe head traumas occur, like a stroke (3). These neurons function like the lost neurons, giving an appearance of regeneration, by expanding the neurons dendritic field to compensate fo r the loss neurons (4). Research has been done on the plasticity of the brain and its implications. The plasticity factor is the brains ability to constantly change its structure and function in response to experiences coming in from the outside. The brain has supportive elements, neurotrophic factors, astrocytes, blood vessels, glial cells that aid in the morphing of its function and structure (4). Neurotrophic cells are critical for the development and maintenance of neuronal communication. In their absence, the neurons they nourish shrivel and die (4).

An increase in neuron size, thicker cerebral size, and more neuron- neuron connection are all examples of the plasticity of the brain. In one study designed to show the effects of rats in a rich and stimulating environment, found that the rats brain weight increased by about 7-10% after 60 days, with synaptic connections increasing by about 20% (4). It has also been experimentally shown that new and novel experiences increase the number of excitatory synapses per neuron and decreases the number of inhibitory ones in the visual cortex (4). The modification of the excitatory and inhibitory balance is a direct result of the plasticity factor in action. Also, the plasticity factor can increase or decrease the number of neurons depending on the richness or depravity of the experience. The neuronal increase was approximately 35-40% more neurons in the olfactory region (4). During human development, connections are being built at the speed of about 3 billion a second, reaching 1,000 trillion connections in the whole brain. All of these many neurons, connections, and maintenance thereof do not exist to remain dormant.

The implications of the plasticity factor include the fact that the brain has been empirically seen to physically reconnect itself, so that it improves its present functional state (3). So perhaps the brain does not use its full potential, after all. Perhaps, instead of less usage, we can improve our usage through education. Biologically, education increases the number of neuronal connections, improving memory, spatial and problem solving skills, and a number of other functions. The plasticity of the dendrites morph or extend and retract its processes when stimulated, in response to neuronal activity, chemicals, and neuronal damage (4). Therefore, dendrites, composing about 95% of the receptor surface that neurons form connections, are the best tools to determine the plasticity of the central nervous system (4). It was experimentally discovered that dendritic fields also change, changing the structural organization of the central nervous system, according to stimulation. Behaviorally, education improves the number of positive values and attitudes about health and an increased self esteem (4). There is evidence that humans can build more brain capacity through specific exercises that increase neuronal connections and efficiency. Education makes us more immune to disease and premature aging (1). And the earlier the educational exercises occur, the increased the mental capacities become (4). If one performs these mental exercises throughout their life, it is like getting a booster shot of mental capabilities. In recent studies, it has revealed a relationship between dendrite atrophy and decreased function and increased dendritic space leads to an increasing function. This suggests that there is a relationship between brain plasticity and behavioral change (4). So if neurons have more connections and are structurally larger, the brain is hypothesized into having a greater influence over behavior. There is evidence that activity caused by experiences could increase the activity of genetic mechanisms responsible for dendritic and synaptic growth, ultimately influencing behavior.

Since there is evidence for the plasticity factor, it does not seem so outrageous for people who are left or right brain dominant to become ambidextrous. Being left or right brain dominant does not imply that the non- dominant hemisphere of the brain is not active at all. Many of the activities that humans perform everyday use both right and left brain specialties, such as sensory input. Hemisphericity is a dependence on one side of the brain to solve intellectual issues and physical issues, like unilateral thinking and headaches and insomnia (5). The body strives for homeostasis, which can not be achieved by being left or right brained dominant. Perhaps the plasticity of the brain can lead to a more holistic brain, functioning in right and left brain dominant activities, like analyzing math problems and addressing issues of emotion. Practice using the neglected hemisphere through mental drills proves useful in becoming a more balanced individual (1). For instance, using the body in new ways helps, like doing routine activities with the non- dominant hand. Another exercise is doing something different everyday, like breaking from your daily routine to allow you brain to experience different situations to produce those chemical and structural changes in the nervous system (1).

It has been displayed that neurophysiological changes affect our behavior. Can it be said that we are getting smarter or optimizing our capabilities? Is there a limit to our capabilities, such that we can only increase our neuronal connections so much and increase our dendritic fields so wide? I believe there is a limit to the increasing of the function of the human brain. A limiting factor is physical material, because we dont see humans with such large or heavy heads due to neurophysiological morphing from experiencing so much in life, that it is difficult to function. Humans lose approximately 100,000 neurons each day after age 30 and the cortex loses about 30% of its neurons between adulthood and age 90 (3). More brain capacity is being associated with a more harmonious and fulfilling life, perhaps by aiding people in becoming ambidextrous and increasing their experiences (1). Does that make Hitler a fulfilled person, because of his many experiences and ability to use strategy (left brain function) and appeal and convert the thinking of the masses (right brain function)? Since I am still not convinced that brain is behavior, I dont think that one can achieve a harmonious life by altering the physical orientation and size of the brain. Where is the influence of the I function in the plasticity factor?


WWW Sources

1)Creative Alternatives website

2)Committee for the Scientific Investigation of Claims of the Paranormal website

3)The Brain Lab website

4) website and Annual Review of Psychology article

5) website and NaturalHealth Journal



Comments made prior to 2007

"Experiments in rats have shown that rats with parts of their brains removed could relearn tasks, and people born with microencephaly can be of normal intelligence, suggesting to some that the much of the brain is unnecessary."

...the rats is just as intelligent as the test thats given ,if passed, doesnt mean other parts of the brain are unneccassary, it might just mean that the other parts of the brain are most easily and commonly used. maybe we were born using different parts of our brains, becouse we are tought nothing, and know nothing, except natrual instincts, to maybe see things or remember things that we dont, becouse we've learned, how to talk, eat, and walk...but they dont test phycic ability or clairvoyance, do they? no. while other parts of the brian get stronger, other parts become more weak, which is naturally said to happen once a scense waekens....another strengthens.

just pretend were living in an age hundreds of years prior to 2006. and some "scientist", "doctor", or " psycotherapist", comes up with a new notion, and they test it, and at that point they think its a great idea and will benefit society. give it a couple more years and they relize well thats not such a good thing to do at all, or that notion doesnt even makes sense. with just a little more insight, a little more research, and a couple years later they find out that the whole idea back fires...when they totally thought they new what they were doin at the time...well it goes on today, obviosly were not as advanced or as smart as we think we are, becouse were comparing ourselves to..."mistakes", the "past" ... Danni, 19 November 2006