As chronic fatigue and rampant sleeplessness turn us all into walking zombies, it’s becoming increasingly miraculous that anyone manages to do what they need to do over the course of a day. According to the authors behind a new Proceedings of the National Academy of Sciences study, we have our brain’s default mode network to thank: This interconnected system of brain regions is what allows our bodies to run on “autopilot,” directing our bodies while our minds are in a haze, they reported on Monday.
Most of us have surprised ourselves by performing everyday functions — like cooking, driving, or even typing out robotic e-mails — without consciously doing so, but for a long time scientists didn’t understand how the brain directs itself when it’s not actively engaged. But as the team of scientists from the University of Cambridge and the University of York explain in their paper, the part of the brain linked to mind-wandering and daydreaming — the default mode network — is the engine powering our self-driving brains. Anatomically, it comprises the brain’s ventromedial prefrontal cortex and posterior cingulate cortex.
The researchers are the first to show evidence that our brains are actually active in the moments we’re not consciously engaging it. In the study, participants were asked to figure out the rules of a simple card game while having their brains scanned in an fMRI machine, which tracks brain activity via changes in blood flow. The game was designed to test cognitive flexibility — our “ability to apply learned rules.”
The brain scans showed that, while participants were actively learning the game (the “acquisition” phase), the parts of the brain associated with memory were the most active. But as participants became familiar with the rules during the “application” phase and no longer had to consciously think while they played, the memory regions disengaged, and the areas belonging to the default mode network lit up. In addition, the hippocampus, parahippocampus, and parts of the visual cortex — areas the researchers linked to faster and more accurate responses — were also more active during this phase, suggesting that people might actually be better at applying learned rules when they’re running on autopilot.
Of course, some tasks can’t be accomplished by the default mode network alone: The researchers write that this system is probably most useful for “automated information processing, i.e. when rapidly selecting appropriate responses under specific, predictable environmental demands.” Everyday tasks, like driving the same route home each day or cooking a favorite meal, don’t change each time we do them, so the brain — which some neuroscientists think is organized to maximize “the anticipation of external events” — can rely on its memory-integrating default mode network to accomplish them. But in cases where this system doesn’t know enough to predict the environment — say, driving in brand-new locations — a “manual mode” takes over, forcing us to pay more attention.
It’s funny that research into the brain’s automated capabilities is taking place just as humans are investigating how to automate the predictable, everyday tasks we do while our default mode networks are engaged. In the future, it’ll be interesting to see whether the default mode network will be any more or less engaged when self-driving cars and other automated technologies take over the “autopilot” role.