Why is it Hard to study the Brain Function?

-People with Brain Damage won't live as long [Usually] -People that have Brain Damage from Injury are Rare, and may not give Consent. -People with Horrible Brain Damage may not even be able to Agree to it, meaning the Family has to choose. This is an Ethical Issue. -The Brain functions in a Machine, could be Different Outside a Machine, and we would not know