Science: A New Map of the Human Brain – WSJ.com.
New brain research eschews the left/right brain standard to a new top/bottom. Further the theory is that the top and bottom of the brain are working in concert to perform tasks, not in conflict with each other. We do not use the top and bottom equally though. Click the link above for the WSJ article.
"This research reveals that the top-brain system uses information about the surrounding environment (in combination with other sorts of information, such as emotional reactions and the need for food or drink) to figure out which goals to try to achieve. It actively formulates plans, generates expectations about what should happen when a plan is executed and then, as the plan is being carried out, compares what is happening with what was expected, adjusting the plan accordingly.
The bottom-brain system organizes signals from the senses, simultaneously comparing what is being perceived with all the information previously stored in memory. It then uses the results of such comparisons to classify and interpret the object or event, allowing us to confer meaning on the world."