The Insula: Behind the Scenes of Your Brain's Attention Switchboard
Have you ever been in a meeting where no matter what, you can’t stay focused? You know it will be disastrous if you actually succumb to sleep, especially when there’s the possibility of drool involved, but you’re still fighting not to nod off.
If there’s a window in the room, it’s pure torture. You dare not look out for fear of ‘going all Walter Mitty,’ and finding yourself in full-blown daydream mode, helping the industrious wasp on the other side of the glass build its nest. (Okay, yes, I looked out—but just for a second. Wasps are fascinating little creatures, aren’t they?)
You can thank your brain’s insula for all of this, according to Daniel Levitin in his new book The Organized Mind. To conserve energy, your brain automatically slips into what neuroscientists call the ‘default mode,’ named by researcher Marcus Raichle. This is a natural state somewhere between sleep and conscious attentiveness.
Whenever you pay attention, your brain is burning glucose reserves. You literally do pay for that attention, and the cost is that you can’t give that attention to something else. It’s a zero sum proposition. The average human’s bandwidth for attention is about 120 bits per second. To put that in perspective, when you’re engaged in a conversation, you’re burning up about 60 bits.
Therefore, two people talking to you at the same time uses your full 120 bits, and you can’t process anything else. Which is why, when a third person tries to butt in and start their own conversation, “fuhgettaboutit.”
In a 2010 paper, Levitin, along with Vinod Menon, describes the insula as acting like a mini attention routing switchboard. (Think old-timey phone operators.) Essentially, it’s a binary switch, absorbing information and instructions from all over the brain and then regulating that input by either connecting up your central executive system (the home of reason, speculation, planning, assessment and focus), or instead plugging into your mind-wandering system of energy conservation, free association and daydreaming.
Interestingly, unless your insula is detecting life-threatening danger signs, it tends to bias towards mind wandering as the default.
This explains why when you sit down in an early morning meeting and inhale a jelly donut, your brain comes online like a storm trooper. The sugar in the donut spikes the glucose in your brain, then burns out. That resulting energy crash, combined with drone of the speaker’s voice, sends a message to your insula: time to change the channel.
You take one final glance out the window and your insula, sensing no real present danger, switches your mind into the default zone, home of Walter Mitty and the land of ‘future self.’ So in a way, when you dose off in a boring meeting, it’s not entirely your fault.
If only the brain came equipped with a drool sensor.