In 1870, german physicians gustav fritsch and eduard hitzig used mild electrical stimulation in an animal's brain to make parts of the body move. when they stimulated the the right side moved.

These German physicians discovered that mild electrical stimulation to parts of an animal's brain, particularly the cortex, allowed for different parts of the animal's body to move. They discovered the brain's motor cortex. 

Stimulating parts of the left or right hemispheres or halves of the brain resulted to movements of certain body parts on the opposite side. Thus, stimulating parts of the left side of the brain caused specific parts on the right side of the body to move. Meanwhile, stimulating parts of the right side of the brain caused specific parts of the left side of the body to move.