Many people will be familiar with this rather strange image:
It’s a depiction of the motor homunculus, which is essentially a “map” of the body located in the brain. The image shows how different spots of the primary motor cortex control different parts of the body.
So, for instance, the spot I’ve highlighted in red corresponds to the muscles in the thumb. If you were to stimulate this spot, say using an electrode, it would cause the thumb to twitch. By stimulating different points and
Source: Discover Magazine