There's lots of research that shows that the structure of the brain IS very important in how it works and how we use it. For a good overview see Steven Pinker's

There's lots of research that shows that the structure of the brain IS very important in how it works and how we use it. For a good overview see Steven Pinker's How the Mind Works. Many of these studies include individuals that had isolated damage to one small part of the brain and how that affects them. They show that specific parts of the brain are involved in highly specialized activities and that the brain is not just a big, nebulous general purpose calculator.