Scientists Say: Cortical homunculus

Your body parts are mapped on to your brain

This homunculus shows the parts of the body next to the areas of the brain that process their sense of touch. The parts that are large use a lot of brain area.

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Cortical homunculus (noun, “CORE-tick-uhl ho-MUN-cuh-luhs”)

The cortical homunculus is an illustration that represents how the brain senses and controls different parts of body. There is one of these maps for our movements. There’s another for our sense of touch. In the cortical homunculus, the size of a body part in the picture corresponds to the amount of the brain devoted to it. So the lips — which are very sensitive to touch and have a lot of space set aside for them in the brain — are drawn very large. The torso is not very sensitive, so it is drawn very small.

In a sentence

With toothpicks and ruler, you and your friends can draw your own homunculus and watch as representations of your body parts grow and shrink.

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Power Words

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cortical   (in neuroscience) Of or relating to the brain’s cortex.

cortical homunculus  The visual picture of how much space each part of the body takes up in the a part of the brain known as the somatosensory cortex. It’s the area of the brain that first processes touch. It can be drawn as a series of body parts mapped onto a brain, or as a human figure with the size of each body part corresponding to its relative sensitivity.

homunculus   (in science) A scale model of the human body that represents certain functions or characteristics.

Bethany Brookshire was a longtime staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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