Q: How do our brains think?
— Elsie Schram, 4
A: To explain how brains think, we can start by asking: What does a nervous system do for an animal? A very simple demonstration of the nervous system is when you’re at the doctor’s office. If the doctor hits your patellar tendon on your knee, your knee reflex sends your leg forward.
That action doesn’t involve your brain. It’s a simple reflex arc with only two neurons, yet it’s already more advanced than what something without a central nervous system — like a plant or a tree — can do.
Another example is if you’re walking outside and suddenly see a circular object heading toward you. Your eye detects the fact that this object is coming toward you, and the signals go from your eye into the visual part of your brain. Your brain then communicates with other neurons, sending signals to muscles in your body that will make you duck out of the way so the object doesn’t hit you.
In order for your brain to think, you need nerve cells that can detect information about the outside world and then those cells can transmit that information to other nerve cells. It’s the transmission of information, the cells talking to each other, that’s the fundamental physical basis for how thinking works.
Another critical part of the nervous system that supports thinking is that nerve cells can change. They can essentially learn about past experiences so they respond differently when an experience is re-encountered.
If you know that there’s a soccer game going on, when you see a ball looming toward you, you probably won’t be as surprised. Stored in your brain, before you even walked to the field, was a representation of what it means to play a game of soccer and what to expect.
A big part of thinking turns out to be the ongoing updating by the brain of the current environmental situation.
Even when you’re not purposefully, consciously thinking, like trying hard to remember a fact or to solve a puzzle, your brain is just as active. It’s always keeping track of where you are in the environment and what events you might expect to happen in the near future.