Siri Hustvedt, a native of Northfield, Minn., and now a New Yorker, has written four novels and two essay collections. She has also, partly because of her history of prolonged and severe migraines, made a broad and eclectic study of neurological, psychological, philosophical and cultural ideas about how the mind and body work together -- or don't. And then life gave her one more good reason to take an interest in the subject. In short, she became her own case study.

In 2006, two years after her father's death, Hustvedt was speaking at a memorial for him at St. Olaf College, where he'd taught for decades. A frequent and confident speaker, she began her speech, only to have her body rebel. From the neck down she shuddered and shook. Her arms flapped. Her knees knocked. "Weirdly," she says, "my voice was unaffected. ... I managed to keep my balance and continue."

This was, for me, the strangest aspect of Hustvedt's condition: not that her voice was unaffected, but that, despite having what amounted to a neck-down seizure, she kept on giving her speech. It is also a bit odd that, while the shaking phenomenon launches the author on a journey in search of answers, a previous episode ("In an art gallery in Paris, I suddenly felt my left arm jerk upward and slam me backward into the wall") merits only a mention.

This book, the result of Hustvedt's wide-ranging research, is a sometimes fascinating, often absorbing and occasionally tiresome sampling of what's been said in various disciplines about how the self is configured as a psychic or physical entity and what happens when that self fragments or splits. For instance, there are the accounts of "alien hand syndrome," in which, in patients with severed neural connections between their left and right brain hemispheres, the left hand literally doesn't know what the right hand is doing.

The anecdotes, from the history of psychoanalysis and science and from Hustvedt's own experience coaching psychiatric patients in writing, are generally the best part of the book. That makes a certain sense, because "The Shaking Woman" is ultimately about the self as story, about taking command -- or ownership, as Hustvedt says -- of the narrative. And if Hustvedt makes us too much of a party to her own quest for ownership, at least she gives us intriguing glimpses of whole worlds of wonder and science and speculation in the contemplation of the self along the way.

Ellen Akins is a novelist in Cornucopia, Wis.