Updated: Apr 27, 2018
Okay... not everything. But we are much smarter about learning how to learn than we used to be.
We once believed that the intelligence and creativity were fixed. We did the best with what we were given. Now we know that the brain is more like Play-Doh than plaster. It’s malleable and it’s constantly growing new neurons. In order to make room for the all of these new cells, it has to get rid of the ones that aren’t pulling their weight. This is neuroplasticity at work, and it’s what lets you get smarter today than you were yesterday.
It’s no secret that the more you do something, the better you’ll be at it. To get better at foul shots, shoot more foul shots. To get better at speaking French, speak more French. This is because neurons that fire together wire together. The more they fire together the stronger they wire together. The brain is like any other muscle in the body, and the more you tap into neural connections, the stronger they get. Every time you repeat a cognitive activity, you reinforce that neural circuit. The more you reinforce it, the stronger it gets.
Think back to how you studied for a high school history test. If you graduated, you learned about how the Reconstruction was impacted by the election of 1876, and the 14th Amendment. (If none of that sounds at all familiar, you’re just going to have to trust me… it’s a real thing.) No doubt you read the material in the textbook several times and listened to your teacher explain it. Maybe you outlined the information highlighting key ideas, and then pored over it until it was seared into your memory. If you did all of that, you probably aced the test.
Okay, now... how much do you remember about the Reconstruction today?
What happened to that neural circuit that you spent so much time building?
Learning is not just about building neural connections. It’s also about getting rid of old ones. It’s called “synaptic pruning” and the “use it or lose it” principle applies here. Unless you're a historian or you enjoy impressing your friends with 1876 trivia, you likely lost all of that knowledge because you didn’t use it.
Think of your brain like a garden. You plant seeds, and then you give them water and sunlight as they grow roots, stems, leaves and flowers. You protect them from critters, pests, and weeds. The more you nurture the plants, the bigger and stronger they grow.
Like a seedling, everything you learn starts out as dendrites that grow out of neurons and connect with other neurons. The more you use that information, add to it, reflect on it and apply it, the bigger and stronger that neural circuit grows. Good neurotransmitters, like serotonin and oxytocin travel along these connections and fertilize them like Miracle-Gro. Other chemicals, like the cortisol we produce with stress, break them down and kill them like Round Up.
Astrocytes, or glial cells, are another type of brain cell, and we didn't know much about them until the 1980s when Dr. Marian Diamond discovered that Albert Einstein had more of them than average. Glia comes from the Greek word for glue and we used to think that they were just that - brain glue that supported the neurons. We've since learned that these cells are essential for brain development, proper metabolic brain function, neuronal health, and now, perhaps, for intelligence itself.
Glial cells have a full-time job. During the day, they enable the neural connections to communicate with each other. They are also on the lookout for circuits that aren’t pulling their weight. When they see an unused connection – like the 1876 election – they mark it with a protein.
The glial cells on the night shift look for the circuits marked with proteins as well as neurotoxins and cells we’ve killed with too much stress (cortisol). Their job is to sweep all of that debris away. But they can only do that when we sleep. During sleep, our neural cells shrink to make the interstitial spaces larger giving the glial cells room to work.
When we don’t sleep well, the glial cells can’t do their job. The neurotoxins and dead cells clutter the brain and the unused connections prevent new and stronger connections from growing. It’s like trying to plant a flower garden in an overgrown lot. The flowers won’t grow until you clear out all of the weeds. Even a quick cat nap or a few minutes of mental downtime can bring the cleaning crew to life to clear out the clutter.
All of this pruning and growing happens without even thinking about it. But we do have control over which neural connections stay and which go. Remember the “use it or lose it” principle? Those connections that you use will stay and get nurtured. Those that you don’t get tossed out with the trash. So, pay attention to what you pay attention to because that’s what your gardeners will tend to.
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