Quirky Questions:

No doubt you’ve heard this piece of trivia at least once–perhaps even a few times. But no matter how trivial (and untrue) this tidbit of information may be, it has managed to become one of the most readily believed and widely accepted medical myths in current culture.

No one really knows where or when, exactly, this myth originated. Some theories attribute it to early neuroscientists or misquotes and misinterpretations of research data. Regardless, it’s easy to see why we propagate it. The desire to become more than who we are is very human. And the notion that we may be able to somehow tap into a vast and unused portion of our brain is so fantastic that it almost seems like an attainable superpower. Who wouldn’t want that?

But what do we really know? During development, the brain is a very complex and plastic organ. It’s a medical fact that when sections of the brain are removed in early childhood–as in the case of a temporal lobectomy for intractable epilepsy–the remaining brain structures are able to compensate and take on the role of the excised portion as if nothing happened. However, about the time we enter adolescence, our brain loses this miraculous plasticity to heal and adapt. That’s when brain damage can become devastating.

What we know from experience is that brain damage is a very serious issue, especially as we get older. For example, even when small parts of the adult brain are affected by stroke, trauma, or tumor, the ramifications may not be so small. Often, patients are left with motor, speech, or even personality impairments. Obviously, these medical facts don’t support the notion that 90 percent of the human brain is unused and dispensable.

What’s also odd about the 10 percent statistic is the implication that decades ago—back when the myth likely originated—scientists had some way of accurately measuring how much of our brain we actually use, when, even with modern brain-imaging technology, we have no way to exactly quantify such a figure. What we do know from modern brain-imaging studies is that we readily use the majority of our brains on a regular basis.

So the next time someone tells you that we use only 10 percent of our brains, you can safely say, “Speak for yourself!”