A Sense Of Self: What Happens When Your Brain Says You Don’t Exist

Science journalist Anil Ananthaswamy thinks a lot about “self” — not necessarily himself, but the role the brain plays in our notions of self and existence.

In his new book, The Man Who Wasn’t There, Ananthaswamy examines the ways people think of themselves and how those perceptions can be distorted by brain conditions, such as Alzheimer’s disease, Cotard’s syndrome and body integrity identity disorder, or BIID, a psychological condition in which a patient perceives that a body part is not his own.

Ananthaswamy tells Fresh Air’s Terry Gross about a patient with BIID who became so convinced that a healthy leg wasn’t his own that he eventually underwent an amputation of the limb.

“Within 12 hours, this patient that I saw, he was sitting up and there was no regret. He really seemed fine with having given up his leg,” Ananthaswamy says.

Ultimately, Ananthaswamy says, our sense of self is a layered one, which pulls information from varying parts of the brain to create a sense of narrative self, bodily self and spiritual self: “What it comes down to is this sense we have of being someone or something to which things are happening. It’s there when we wake up in the morning, it kind of disappears when we go to sleep, it reappears in our dreams, and it’s also this sense we have of being an entity that spans time.”