It may be the deepest mystery of philosophy, psychology, and neuroscience: how does the brain unite to create the self, the subjective "I"? In Altered Egos, Dr. Todd Feinberg presents a new theory of the self, based on his first-hand experience as both a psychiatrist and neurologist. Feinberg first introduces the reader to dozens of intriguing cases of patients whose disorders have resulted in what he calls "altered egos": a change in the brain that transforms the boundaries of the self. He describes patients who suffer from "alien hand syndrome" where one hand might attack the patient's own throat, patients with frontal lobe damage who invent fantastic stories about their lives, paralyzed patients who reject and disown one of their limbs. Feinberg argues that the brain damage suffered by these people has done more than simply impair certain functions--it has fragmented their sense of self. After illustrating how these patients provide a window into the self and the mind, the author presents a new model of the self that links the workings of the brain with unique and personal features of the mind, such as meaning, purpose, and being. Drawing on his own and other evidence, Feinberg explains how the unified self, while not located in one or another brain region, arises out of the staggering complexity and number of the brain's component parts. Lucid, insightful, filled with fascinating case studies and provocative new ideas, Altered Egos promises to change the way we think about human consciousness and the creation and maintenance of human identity.