Functional Imaging of the Human Brain: A Window into the Architecture of the Mind

The last 20 years of brain imaging research has revealed the functional organization of the human brain in glorious detail. This work has identified a set of regions of the cortex, each of which is specifically engaged in a particular mental task, like the recognition of faces and places, perceiving speech sounds, understanding the meaning of a sentence, and thinking about another person’s thoughts. Other brain regions play a more general role in intelligence, getting engaged when we perform nearly any difficult mental task at all. Each of these regions is present, in approximately the same location, in virtually every normal person. I like to think of this initial rough sketch of the functional organization of the brain as a diagram of the major components of the human mind, a kind of picture of who we are as perceivers and thinkers. But at the same time this new map is just the barest beginning, revealing a vast landscape of unanswered questions. What other specialized regions exist in the cortex, and what are they specialized for? How do these regions arise in development, and how much of the organization of the brain is specified at birth? Perhaps most fundamentally, why, from a computational point of view, is the brain organized the way it is, with this combination of highly specialized brain regions, along with very general-purpose systems? These open questions are much harder to answer, but I will mention a few tantalizing glimmers that are beginning to emerge from labs around the world.