9 Brainy Facts About the Neocortex

The human body is an amazing thing. For each one of us, it’s the most intimate object we know. And yet most of us don’t know enough about it: its features, functions, quirks, and mysteries. Our series The Body explores human anatomy part by part. Think of it as a mini digital encyclopedia with a dose of wow.

The brain is arguably the one organ that makes you who you are—and the largest part of the brain is the neocortex. Taking up a vast amount of space in your skull, the neocortex is what allows you to do many things you take for granted, such as write and speak, have social interactions, and muse philosophically about the meaning of life. But you might not have known these nine crucial facts about this critical part of your brain.

1. IT'S THE "NEWEST" ADDITION TO YOUR BRAIN.

You might have guessed that, considering the name. The origin of the neocortex is surprisingly recent, evolutionarily speaking. It dates back to reptiles of the Carboniferous Period, about 359 million years ago. It emerged then as “a uniform, six-layered sheet consisting of radially deployed neurons” in the first small mammals who appeared during the transition of the Triassic and Jurassic periods.

2. IT TAKES UP MOST OF THE SPACE IN YOUR BRAIN.

The human neocortex accounts for a whopping 76 percent of your gray matter.

3. YOU WON'T FIND IT IN BIRDS OR REPTILES.

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The reason birds, lizards, and frogs can’t do much more than attend to the basic functions of survival, and certainly will never write a poem or perform a piece of theater, may be due to the fact that they lack a neocortex. And yet some birds are incredibly clever. The term bird brain is turning out to be quite the misnomer.

4. THE NEOCORTICES OF EARLY MAMMALS WERE MUCH SMALLER.

The fossil record tells us that early mammals were typically small—generally somewhere between mouse- and cat-sized. They likely had small brains with much smaller neocortices [PDF].

5. YOUR NEOCORTEX CAN DEVELOP NEW NEURONS IN ADULTHOOD.

In 1999, contrary to previous theories, scientists were surprised to discover that the adult neocortex can in fact experience neurogenesis—the growth of new neurons. This helped develop a theory about plasticity in the brain—the idea that even adult brains can be retrained and strengthened after adulthood.

6. IT MAY BE THE SEAT OF CONSCIOUSNESS.

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The neocortex controls language and consciousness, among other things. It is also involved in higher functions such as sensory perception, motor commands, spatial reasoning, and conscious thought.

7. CORTICAL NEURONS ARE NOT BORN IN THE NEOCORTEX.

As the cortex develops in mammalian species, its neurons are not generated within the area, but migrate from neighboring “transient proliferative embryonic zones” near the surface of the cerebral lateral ventricles.

8. THE NEOCORTEX BUILDS CONNECTIONS BETWEEN PARTS OF THE BRAIN.

A team at Yale’s Kavli Institute for Neuroscience found that the human brain is “like a neighborhood”—better defined by the community living within its borders than its buildings. The team writes, “The neighborhoods get built quickly and then everything slows down and the neocortex focuses solely on developing connections, almost like an electrical grid.”

9. INJURY TO THE NEOCORTEX MAY COST YOU THE ABILITY TO COMMUNICATE.

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If the neocortex is injured through accident, surgery or head trauma, patients may lose any number of cognitive abilities including speech, space recognition, eyesight, motor control, the ability to recognize social cues and more. Wear your helmets!