If personhood is the quality or condition of being an individual person, "brainhood" could name the quality or condition of being a brain. This ontological quality would define the "cerebral subject" that has, at least in industrialized and highly medicalized societies, gained numerous social inscriptions since the mid-20th century. This article explores the historical development of brainhood. It suggests that the brain is necessarily the location of the "modern self," and that, consequently, the cerebral subject is the anthropological figure inherent to modernity (at least insofar as modernity gives supreme value to the individual as autonomous agent of choice and initiative). It further argues that the ideology of brainhood impelled neuroscientific investigation much more than it resulted from it, and sketches how an expanding constellation of neurocultural discourses and practices embodies and sustains that ideology.