This article presents an ethnographical and historical analysis of the mode of being that is constituted when people use neurofeedback (brainwave training) for self-improvement. I analyse how human brainwaves have been associated with the psyche since their first demonstration by the psychiatrist Hans Berger, how they were connected to personality types by the cybernetician Grey Walter, and made trainable by the psychologists Joe Kamiya and Barry Sterman. I compare these cases with the reports of contemporary neurofeedback practitioners and users, and (...) demonstrate that working on the self by working on the brain constitutes a complicated relationship between the brain and the self. Moreover, I demonstrate that combinations of brains and selves, material and spiritual ideas, and biological and social explanations are not confusions due to the ignorance of neurofeedback users, but amalgamations that emerged in the work and ideas of early scientists. (shrink)