How do we know so much about the brain?

The main techniques used in early brain studies involved stimulating areas of the brain with small amounts of electricity. This was done during surgical operations for certain types of very severe epilepsy. The brain operates on the basis of electrical signals transmitted from neurons (brain cells) in one area to neurons in another. During the operations, surgeons were able to stimulate parts of the brain with tiny amounts of electricity. They were then able to study the effects that occurred.

Knowledge of brain function was also gained when surgeons had to remove certain parts of the brain affected by cancer. It then became apparent which functions of the brain were lost.