The Nuance
This Is What’s Happening in Your Brain When You’re Daydreaming
Unlocking the mysteries of the brain’s default mode network
What does the human brain do with its free time? A team of neuroscientists at the Washington University School of Medicine in St. Louis wanted to find out, so they recruited a few dozen people and asked them to sit in PET scanners with their eyes closed, leaving their minds free to wander.
“Many suspect that left unconstrained, [the brain’s] activity will vary unpredictably,” those neuroscientists wrote in the 2001 study paper that detailed their findings. But their PET scan data argued otherwise. The researchers’ findings revealed that specific areas of the brain — including both the posterior cingulate cortex and the precuneus — reliably switched on when people’s minds were allowed to wander freely. Meanwhile, many other regions predictably switched off. This suggested that the brain, rather than engaging in random and uncoordinated activity, tended to slip into a kind of resting operational state.
“People are still debating all its functions, but it seems to help us imagine the future — kind of like mental time travel.”
