The Man Who Wasn’t There: Investigations into the Strange New Science of the Self
by Anil Ananthaswamy
Dutton, 2015 ($26.95)

For centuries philosophers, theologians and psychologists—including René Descartes, the Buddha and William James—have mused over the nature of the self: Is it an illusion, or is it real? If it does exist, where in the brain does it reside?

Modern neuroscience has not resolved the debate but does offer tantalizing glimpses of the brain regions shaping our sense of self, argues science writer Ananthaswamy in his new book The Man Who Wasn't There. In particular, he focuses on what we can learn from certain neuropsychiatric disorders, such as Alzheimer's disease and schizophrenia, that ultimately serve to dissolve our identity.

Ananthaswamy recounts, for instance, the story of a patient who exhibited the hallmark symptom of Cotard's syndrome: he insisted he was brain-dead despite being alert enough to make that declaration. This rare disorder challenges the classic Cartesian philosophy of the self: “I think, therefore I am.” Studies reveal that sufferers show abnormally low metabolic activity in the frontoparietal network, which is involved in generating conscious awareness. The connection suggests that these neural networks may be at least partially responsible for our sense of self.

Other disorders also provide ideas about how our sense of identity may form in the brain. Ananthaswamy notes that people with schizophrenia face a twisted version of reality. Some lose agency over their thoughts, experiencing hallucinations and paranoia. Functional MRI studies indicate that those with auditory hallucinations exhibit hyperconnectivity among brain regions involved in speech production, speech perception, hearing and threats. These overactive neural networks, he says, change our core perceptions of the world and of ourselves—and may turn innocent thoughts and daydreams into something more malevolent.

Alzheimer's may offer some of the most profound clues about the origins of self. As the disease progresses, it ravages our memories. As a result, we irrevocably lose the knowledge of our history and the narrative we have created about who we are.

The Man Who Wasn't There is a thought-provoking read. Overall, Ananthaswamy's collection of intriguing cases suggests that the self cannot be pinned to any one spot but emerges instead from an intricate network of brain regions. Although a complete understanding of the self may elude us, Ananthaswamy relays many interesting advances and, at the same time, challenges us to contemplate who we really are.