Nick Payne’s intriguing play at Manhattan Theatre Club is cerebral both figuratively and literally: it’s brainy and it’s about the brain. Just as quantum physics played an important role in “Constellations,” his last play at MTC, neuroscience is at the center of this one. In an author’s note, Payne says that the play is loosely based on real events and cites ten sources that inspired him. The three main narratives are about Thomas Harvey, the pathologist who took Einstein’s brain and wasted the rest of his career trying to find something special about it; Henry Maison, a young man who, after experimental surgery for epilepsy, was unable to form new memories for the rest of his long life; and Martha Murphy, a fictional middle-aged neuropsychologist with a dim view of human autonomy, trying to reboot her life after a divorce. There are also several subsidiary stories woven into the narrative. The gimmick is that all 20 roles are played by four actors — Geneva Carr, Charlie Cox, Heather Lind and Morgan Spector —who transition between characters with lightning speed. Text on the rear wall identifies the play’s three sections — Encoding, Storing and Retrieving. This segmentation seemed arbitrary and the moment of stylized movement and gestures that introduced each one was an unnecessary distraction. As in any pastiche, some stories are better than others. I wished that some had been prolonged and others had been attenuated or even eliminated. I found Martha’s story not very compelling, but was extremely moved by Henry’s tale. The actors are wonderful, particularly Carr and Cox. Scott Pask’s strikingly simple set consists of a large circular platform with four chairs backed by a semicircular wall, all in charcoal, with a ring of lights above the wall. Catherine Zuber’s costumes are all in various shades of gray. Director Doug Hughes skillfully juggles the many strands so that the audience can usually find its bearings without undue difficulty. I admired Payne’s ambition and intelligence even when an occasional scene misfired. Running time: 90 minutes; no intermission.