265 Massachusetts Avenue, Cambridge, MA 02139 csf@cambridgesciencefestival.org

Curiosity Challenge: How do Brains Think?

How do brains think? (Maise, 8)

Hi Maise,

That’s a good question! You probably know that your brain is important for a lot of what you do: learning new lessons in school, remembering those lessons when you take a test, controlling your hands as you write the answers to your test, and even telling your lungs to breathe while you’re working! Your brain works in a similar way to do all those tasks.

In the early 1900s, a scientist named Ivan Pavlov did a famous experiment with his dogs that helped… Click To Tweet

The main way your brain works is by making connections between its different parts. In the early 1900s, a scientist named Ivan Pavlov did a famous experiment with his dogs that helped us learn how the brain makes these connections. Pavlov wanted to know if he could train his dogs to think about food every time he rang a bell. He started by ringing a bell every time he fed his dogs. One day Pavlov rang the bell without giving the dogs food, and he noticed that this made the dogs start drooling. Since dogs drool when they are thinking about food, Pavlov knew he had successfully trained his dogs to think about food when he rang the bell.

Legend: 1. Before training the dogs, they only drooled when Pavlov gave them food. 2. They did not drool when Pavlov rang the bell. 3. Pavlov trained the dogs by giving them food at the same time he rang the bell. 4. After the training, the dogs drooled when Pavlov rang the bell.

Pavlov’s training made a new connection within the dogs’ brains. This new connection was between the sound of the bell and the idea of food. When Pavolv rang the bell, the brain used this connection to make the dogs think about food. If you learn a new word in school, your brain will do the same thing to make a connection between the new word and words that you already know. Then, when you hear the new word, you’ll remember what it means because of its connection to words you know. To understand how the brain makes these connections, we need to learn a little bit more about the brain.

When you imagine a brain, what does it look like? Click To Tweet

When you imagine a brain, what does it look like? Maybe a squishy, slimy, bumpy lump? That’s about all a brain looks like when you look at it normally. But you might be surprised that if you look at the brain under a microscope, it looks completely different. Think about how when you see pictures of Earth taken in outer space, all you see is oceans and continents, but if you take pictures closer to Earth’s surface, you can see cities, houses, and roads. The same thing is true for the brain: when we zoom in on the brain, we can see that it’s made up of billions of individual units called cells.

There are many different kinds of cells in your brain, but the ones that are most important for thinking are called neurons. Neurons have a special shape that makes them good at making connections with each other. On one end, they have branches called dendrites, and on the other end, they have a long extension called an axon. The dendrites of one neuron connect with the axons of other neurons. These connections allow neurons to communicate with one another.

Legend: Picture of a neuron.

Each neuron in the brain communicates only about certain things. In Pavlov’s dogs, there were neurons that “talked”* about the sound of the bell and neurons that talked about food. Every time the bell rang, the neurons that talked about the bell would send a message down their axons and across the brain to let other neurons know the bell was ringing. Every time Pavlov gave the dogs food, the neurons that talked about food would do the same thing.

Legend: 1. Before the training, the food neurons would only talk about food when the dog saw food. 2. They would not talk about food when Pavlov rang the bell. 3. During the training, the connection between the bell neuron and one of the food neurons got stronger. 4. After the training, some food neurons talked about food when Pavlov rang the bell. This made the dog drool in response to the bell.

Scientists think that during the dogs’ training, some of the neurons talked about the bell made stronger connections with neurons talked about food. This meant that every time Pavlov rang the bell, the food neurons would get lots of messages from the bell neurons. In response to these messages, the food neurons started talking a lot, and this made the dogs think about food.So when you think, your neurons are really just communicating with each other. They are making new connections based on the lessons you are learning, and they are using those connections to help you remember the right answers on your tests.

I hope that answers your question. Thinking and learning are really complicated processes that scientists are still working hard to understand. Maybe you can one day do your own experiments to help us understand the brain!

*I’m using the word “talk”, but neurons don’t really talk like you and I do. They have their own way of communicating that you can read about here if you’re interested.


Kelsey Tyssowski is a graduate student who studies neuroscience and genetics at Harvard Medical School.

Figure 1 By Maxxl² (Own work – vectorized Pavlov dogs conditioning) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons

Leave a Reply

Your email address will not be published. Required fields are marked *