The protagonist and narrator of E. L. Doctorow’s twelfth novel, Andrew’s Brain (Random House, $26), is a clumsy cognitive scientist who relates the story of his life from an undisclosed location to an unnamed psychiatrist. His anxious monologue — interrupted occasionally by the analyst’s dopey questions — is at once marriage plot, 9/11 novel, and neuroscience brief. Andrew isn’t a very convincing proponent of his subject. His despair over the (misleading) finding that brains “make our decisions before we make them,” for example, tells us a good deal about his own fears and almost nothing…