At best they will be able to help handicapped by reconnecting broken links 



 First because it is impossible to program pain in a computer by logical equivalence it proves our spiritual nature . 


Even without that very large can of worms it would be extremely difficult to supplant large parts of the brain with superior functionality and indeed  you would need to replace essentially everything for it to workbetter so what is left of the person 

 Why bother with the biological when it's just an Al you have made .