Do we only use 10 percent of our brain?

There is no definitive source for the idea began that we only use a fraction of our brain. People have linked it back to the work of 19th Century American psychologist William James, who claimed that we are merely using a “small part of our possible mental and physical resources”. This was picked up by Dale Carnegie in his hugely influential 1937 best-seller, How to Win Friends and Influence People, where he declared that humans only use 10 percent of our brain. In both cases the statement was ambiguous since it could indicate either the brain or mind, which are very different things.

The fact is we use every part of our brain, and a lot of it is active most of the time, whether you are driving a car, sleeping or reading this article. We know this thanks to neuro-imaging techniques such as PET scans and MRIs, which allow us to study the brain in ways that were unheard of in the early 20th century.

Back then, researchers were not able to see the totality of the brain in action, and focussed instead on investigating what the different sections did. In the early 1900s, Psychologist Karl Lashley removed portions of rats’ brains and tested their ability to find a path through a familiar maze. While results varied, Lashley noted that certain sections of the brain store memories, while others perform different tasks. These experiments led to the controversial use of surgical lobotomies in the 1940s and early ’50s in America. By cutting or scraping sections of the brain, neuro-surgeons could alleviate the symptoms of patients with mental issues, but usually with grave side effects to the patient’s personality or intellect.

This crude approach showed that the brain is not as simple as early tests seemed to indicate, and can react in very different ways to trauma. We are all familiar with the stories of people who have recovered lost skills, thanks to the brain effectively rewiring itself. Perhaps the most dramatic example is the case of Phineas Gage. The 19th century American railroad worker suffered a horrific accident where a metal rod smashed through his skull, destroying much of his left frontal lobe. Miraculously, he survived and was able to work again. His personality did change, though even this partially rectified itself over time.

“Rory Curtis woke from a six-day coma, speaking French and convinced that he was Matthew McConaughey”

The brain can also recover with unexpected side effects. In 1985 a British pianist, Clive Wearing, contracted a viral infection that destroyed his hippocampus, the part of the brain that stores memories. He was unable to recognise anyone but his wife or hold a memory for more than 30 seconds.

More recently, Rory Curtis, a semi-professional footballer, sustained brain injuries in a car crash last year. He woke from a six-day coma and spoke in perfect French to the nurse, a native speaker herself. Curtis was also unable to recognise himself upon looking at his mirrored reflection and was initially convinced that he was Hollywood actor Matthew McConaughey. Once again, researchers have no idea how this happened.

Finally, what of the mind itself? If William James was talking about increasing our mental capacity, what have we learned since then?

Last year the findings of a major study by the US government were released. A group of 70-year-old subjects, who underwent cognitive training for ten years, performed daily activities significantly better than counterparts of the same age.

A recent NYU study tracked blood flow to the brains of Tibetan monks while they meditated. The practise was shown to dramatically increase neuroplasticity and awareness. Further research showed that monks had a higher physical capacity for attention, happiness, empathy and altruism.

There is much research still to be done into why and how this happens. But it does show that, while the brain is not capable of superhuman feats, with sustained training our minds can be a powerful tool that help make us better – and happier – human beings.