Tuesday, June 28, 2011
Limitless: How can we unlock the full potential of the brain?
The trailer for the movie "Limitless" depicts a young writer who starts taking a drug that his drug dealer tells him will unlock the other 80% of his brain. The character, portrayed by Bradley Cooper, becomes fantastically intelligent and quickly wealthy and famous. Could this happen? Not so sure. A number of smart drugs, memory enhancers and “nootropic” supplements have been shown to slightly improve memory, motivation, attention and concentration. Vitamins B and C, folate, Omega-3, Ginkgo biloba, other herbals and proprietary blends of these like “Focus Factor” seem to help cognitive function. Central nervous system stimulants like caffeine, Adderall and Ritalin are more powerful, and have proven effects on mental ability, but it is not completely clear how any of these increase mental through-put. Some increase the effects of certain neurochemicals, some dilate blood vessels, some stimulate nerve growth, and most cause neurons to work harder. Simply put, most neurotropic drugs give the brain more energy to power its searches for appropriate memories. Does this mean that the brain is being used more, or that more of the brain is being used?
Is it true that humans only use 20% of their brain? No one can be sure because there is actually no way of knowing quite what this statement is trying to say. It is clearly not true that large portions of our cortex remain unused. If you watch the video results of an fMRI scan you will see that as a person does various tasks and is exposed to various stimuli, virtually the entire cortical surface will light up at one time or another. It is true that at any one time, only a small fraction of the neurons in the brain are being used maximally. But this is a good thing because the unused neurons would insert inappropriate and superfluous content that would be distracting and would take away from the specificity of thought.
It is helpful that we only use a limited percentage of our brains at a time. The brain has dozens of dedicated processing areas, each fine-tuned to solve particular problems, most of which would be irrelevant to a specific task at hand. In fact, much of the brain is designed around quieting or inhibiting extraneous stimuli so that only the most pertinent things can make it into consciousness. Your mind is able to do its work without distractions because your brain is constantly suppressing activation in areas that may seem to hold pertinent memories, but have proven in the past to be misleading. Arguing that we would be better off using 100% of our brain is like arguing that it is better to use each of the tools in a Swiss Army knife, at the same time, for the same project, all at once.
Brain researchers like Karl Lashley, in the 1950s were confused by certain experimental results and were falsely led to assume that the entire cortex of the brain was undifferentiated and that individual areas do not specialized in specific tasks or activities. Outdated principles, such as “mass action” and “equipotentiality” conceptualized the cortex as a homogenous pool of neurons where function could not be localized. Lashley and other neuroscientists of his day saw the individual tools of the brain's Swiss Army knife as interchangeable and able to be summed together. These conceptualizations were wrong but probably contributed greatly to the 10% myth. In fact, it would follow logically from his principles that if specific brain areas do not have particular jobs and if we only use a small minority of brain cells at any time, that we could increase mental ability simply by increasing the number of active areas. Too bad it isn't that easy.
Activating inappropriate memories will not increase intelligence, but how about increasing the span of activity of the most relevant memories? As we think, we hold and let go of certain memories. If we could increase the time that certain helpful memories are activated and available to working memory then this, I believe, would increase intelligence. The brain area to target in order to do this would be the prefrontal cortex. I think that the movie Limitless, does an amazing job of portraying the effects of prolonged prefrontal activation or “hyperfrontality.”
The best kind of neurotropic drug that I can imagine would increase activity in the lateral prefrontal cortex. This would make it so that one was able to drag even more of their visual and verbal imagery with them through time. The PFC is like a switchboard with contacts in all kinds of other brain areas. The harder the PFC works, the longer various representations and subroutines can be maintained. In some senses, this WOULD allow someone to use more of their brain. Using time and mental resources to recall deactivated memories is like trying to use your fingernails to pry out the implements of a Swiss Army knife. Increasing PFC activity though, would be akin to having the most recently used tools in the knife unsheathed and ready for implementation.