Half of the human brain can be removed without affecting memory or personality . It's called HEMISPHERECTOMY . Unbelievably, the surgery has no apparent effect on personality or memory. The first known hemispherectomy was performed on a dog in 1888 by German physiologist Friedrich Goltz. In humans, neurosurgeon Walter Dandy pioneered the operation at Johns Hopkins University in 1923 on a brain tumor patient. A hemispherectomy is a rare surgery where half of the brain is either removed or disconnected from the other half.