What does the brain really do?

Have you ever heard that our brains are wired for fight-or-flight when we face danger? It’s a popular idea, but what if that’s not the whole story?

Lisa Feldman Barrett from Northeastern University explains that our brains don’t just react to danger with a fight-or-flight response. Instead, the brain’s main job is to predict what might happen next and prepare for it. This process of constantly guessing the future uses up a lot of energy, which can make us feel tired or stressed, especially when things are uncertain, like during tough times or big events.

The myth of the "triune brain"

Many people believe that our brains have special circuits just for fighting or fleeing when we feel threatened. This idea comes from an old theory called the “triune brain,” which says that the brain has three layers: one for survival instincts, one for emotions, and one for logical thinking. According to this theory, the lowest part of the brain, often called the “lizard brain,” controls our survival instincts like fear or hunger, while the top part, the “neocortex,” helps us think logically and keep our emotions in check.

However, this theory isn’t really true. Humans didn’t evolve directly from reptiles, and scientists have found that mammals, including humans and mice, have similar types of brain cells, even in the areas that control thinking. Studies also show that there’s no one part of the brain that only controls emotions, and the thinking part of the brain isn’t just for rational thoughts.

So, what does the brain really do?

Research using brain scans shows that a part of the brain called the periaqueductal gray (PAG), which was once thought to only handle fear, is active all the time, even when we’re doing everyday things like comparing letters on a screen. This means the PAG isn’t just about fight-or-flight responses; it’s involved in managing our body’s functions every day.

Scientists studying mice have also found that when a mouse smells a predator, it doesn’t simply freeze or run away. Instead, it moves back and forth, checking out its surroundings to gather more information. This shows that the brain doesn’t just react to danger; it’s trying to figure things out and reduce uncertainty, just like humans do when we face confusing situations.

Our brains are always making predictions about what will happen next

For example, when someone is about to sneeze, your brain picks up on little clues, like a slight head movement, and prepares you to turn away even before the sneeze happens. This process happens so quickly that it often feels like we’re reacting automatically, but it’s really our brain predicting the future.

Dealing with uncertainty is tough for the brain because it takes a lot of energy. When there’s a lot of uncertainty—like when we’re stressed or bombarded by news of bad events—it can leave us feeling drained and exhausted. Stress is really just your brain getting ready to spend energy, whether for avoiding danger or just handling everyday tasks like getting up in the morning.

Uncertainty isn’t always bad, though. People often seek it out by trying new things, like tasting new foods or learning new skills. The important thing is managing uncertainty so it doesn’t become overwhelming.

In short, the brain’s job isn’t just about reacting to threats with fight-or-flight. It’s always predicting what might happen next and preparing for it. When we face a lot of uncertainty, it can be tiring, but it’s all part of how the brain helps us survive and thrive in an unpredictable world.

Reference:

Barrett, L. F. (2024, August 8). The ‘Fight or Flight’ Idea Misses the Beauty of What the Brain Really Does. Scientific American. https://www.scientificamerican.com/article/simplistic-fight-or-flight-idea-undervalues-the-brains-predictive-powers/

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