What methods have scientists used to map functions onto particular brain regions?

What will be an ideal response?

A good answer will include the following key points:
+ Studies of children with brain damage — Children who suffer brain injuries provide valuable insights into brain structures and function in that if a region of the brain regulates a particular function, damage to that region should impair the function.
+ Studies of electrical activity — If a region of the brain regulates a function, then the region should show distinctive EEG (electroencephalogram) patterns while a child is using that function.
+ Studies using imaging techniques — Functional magnetic resonance imaging (f-MRI) uses magnetic fields to track the flow of blood in the brain as participants perform different cognitive tasks.