“The actress playing me was trying to pick up my mannerisms. At the same time,” she said, recalling professional lessons learned, “I was trying to pick up hers, because she was much more convincing than I am  she had a little smile that was triumphant, but also just so happy for the patient. I was imitating her imitating me.”

The office in which Dr. Flaherty writes is one floor down from her movement disorders clinic at Massachusetts General  filled with fossils and masks, neurological instruments pinned to a corkboard, books by Darwin, Mann and Virginia Woolf, posters of seminars and art exhibits based on “The Midnight Disease.”

Letters run up the back of her wrist. They are one consequence of hypergraphia, the overwhelming urge to write; she writes during manias and edits during depressions. (She keeps the illness under control with medication.) Dr. Jerrold F. Rosenbaum, chief of psychiatry at Mass General, says he used to get notes from Dr. Flaherty on napkins.

“I save everything she sends me, which I don’t do with anyone else,” he said. “She has enhanced theories of the mind  enhanced in quantity, quality, volume and intensity.”

The wrist notes could be on any of a dozen topics. They may be more thoughts on empathic pain, or about research she is conducting on the side about light boxes and creativity in Harvard undergraduates.

Maybe they are about the informal consultation she made several years ago to an Off Broadway adaptation of “A Doll’s House,” directed by Lee Breuer, a former colleague of hers at the Radcliffe Institute at Harvard, where they were both fellows in 2005.

When weeping during a scene, the actress who played Nora was alarmed upon noticing that the mascara ran from her left eye more quickly than from her right. Dr. Flaherty reassured her that the neurology was normal: the right brain, which controls the opposite side of the body, also controls negative emotions. Therefore, one side seems, and is, sadder than the other. This will go in Dr. Flaherty’s next book, which will be about the neurobiology of illness behaviors ranging from hysteria to stoicism, and, of course, empathy.