The brain contains many different functional and anatomical regions. However, brain tissues are sufficiently uniform that the great variety of types of processing in which they engage poses a significant theoretical challenge. How can functionally different kinds of processing, such as verbal memory and reasoning, visual and auditory memory, and mental imagery, all be supported, and appropriately segregated and integrated as needed by the relatively uniform electrochemical activity of the brain's neurons? In Aging, Representation, and Thought, Matthew J. Sharps provides an empirically based, functional answer to this critical question, from the standpoint of modern cognitive psychology.