When considering large portions of the brain, we need to think about systems—not dichotomies. A system has inputs and outputs, and a set of constituent components that work together to produce appropriate outputs for particular inputs.

A bicycle is a familiar system: The inputs are forces that push down on the pedals, slight movements of the rider’s body made in the act of balancing, and force that moves the handlebars. The components include the seat, the wheels, the handlebars, the pedals, the gears, the chain, and so forth. The outputs are the bike’s forward motion, keeping upright, and going in a specific direction, all at the same time. Crucially, the components are designed to work together to produce appropriate outputs for the system as a whole—for the entire bike.

The same is true of the brain: It has different areas that do dif­ferent things, and the result of the brain areas’ working together is to produce appropriate outputs (such as your avoiding an object) for particular inputs (such as specific sights and sounds). For instance, if you see a car roaring toward you, you jump out of the way.

Just remembered I had read this related article stashed by Joyce Park:

http://pandawhale.com/post/30091/science-a-new-map-of-the-human-brain

Four Cognitive Modes

Four distinct cognitive modes emerge from how the top-brain and bottom-brain systems can interact. The degree to which each of the brain systems is used spans a continuum, ranging from highly utilized to minimally utilized. Nevertheless, for our purposes it is useful to divide the continuum into “high” and “low” categories.