Nathalia Gjersoe writes: Luc Besson’s latest sci-fi romp, Lucy, is based on the premise that the average person only uses 10% of their brain. This brain-myth has been fodder for books and movies for decades and is a tantalizing plot-device. Alarmingly, however, it seems to be widely accepted as fact. Of those asked, 48% of teachers in the UK, 65% of Americans and 30% of American Psychology students endorsed the myth.

In the movie, Lucy absorbs vast quantities of a nootropic that triggers rampant production of new connections between her neurons. As her brain becomes more and more densely connected, Lucy experiences omniscience, omnipotence and omnipresence. Telepathy, telekinesis and time-travel all become possible.

It’s true that increased connectivity between neurons is associated with greater expertise. Musicians who train for years have greater connectivity and activation of those regions of the brain that control their finger movements and those that bind sensory and motor information. This is the first principle of neural connectivity: cells that fire together wire together.

But resources are limited and the brain is incredibly hungry. It takes a huge amount of energy just to keep it electrically ticking over. There is an excellent TEDEd animation here that explains this nicely. The human adult brain makes up only 2% of the body’s mass yet uses 20% of energy intake. Babies’ brains use 60%! Evolution would necessarily cull any redundant parts of such an expensive organ. [Continue reading…]