No reason one thing can't perform several functions, Donuel.

Too often we think of the brain as a set of areas that perform single functions. It is, instead, a giantic network with tremendous redundancy. Watch any stroke victim as they recover -- slowly! -- speech and movement. Or some of the victims of Iraq who have suffered brain trauma by injury and contre-coup injury.

Nor do I think that the brain is a digital computer, especially if you mean that as a computer which only functions in a binary environment. Tertiary, quaternary, perhaps, but much more than a simple on-off setup.