It's often said that humans only use 10 percent of their brains, a popular myth that has provided endless fodder for science-fiction writers. According to the myth, if humans could only find a way to tap into the other 90 percent, then they could become savants, "Good Will Hunting"-esque geniuses, perhaps even psychics.

Unfortunately, it's simply not true that humans only use a small fraction of their brains. They use all of it, of course. But like most myths, there's a subtle string of truth at the heart of it, connecting all the beads of untruth together. For instance, one possible source for the 10 percent myth is that only about 10 percent of our brains are made up of neurons. The other 90 percent is composed of non-neuronal cells, such as glial cells, that provide other functions required for the healthy operation of the brain.

There may be hope yet for the pro-myth crowd, however. Scientists have recently produced a cocktail of small molecules that can be swallowed in the form of a pill that has the power to transform non-neuronal glial cells into functioning neurons for brain repair, reports In other words, it may soon be possible to take a pill that can transform some of the 90 percent of the brain that is not directly used for the processing of information into cells that do have such a purpose.

This news might remind some of the movie "Limitless," in which a man played by Bradley Cooper ingests a brain-enhancing pill that transforms him into the smartest man alive. Though the recently developed real-life version of this pill doesn't quite work in this way — you won't become an instant genius by taking the pill — it does raise the possibility of expanding the neuronal capacity of the brain. And who knows what might be possible with future developments?

For now, the pill is being developed specifically as a brain repair drug. Its most immediate application will be for improving the cognitive functions of those with diseases like Alzheimer's, or for aiding the recovery of those with brain trauma.

"Our dream is that, one day, patients with brain disorders can take drug pills at home to regenerate neurons inside their brains without any brain surgery and without any cell transplantation," explained Gong Chen, professor of biology at Penn State University and lead researcher in the development of the drug. "Our invention of the small-molecule cocktail helps us to make a huge step closer to that dream."

The pill has a long way to go before it can be made available to patients, however. Human trials have not been performed and it's unclear what kinds of side effects might occur. After all, glial cells serve an important brain function. Transforming some of them into neurons may lead to poor brain function in other ways. (In the "Limitless" film, overuse of the pill can lead to death, for instance.)

Even so, the idea of a "Limitless"-like, brain-enhancing pill is certainly something that will garner further research. It's just another example of how the line between science fiction and science fact can be very thin indeed.