Davis et al. 2 challenge the notion that brain imaging may ultimately replace self-report as a more reliable and objective measure of pain. 11, 12 We agree that pain is fundamentally subjective with self-report providing the most complete and reliable access to another's pain. 9 We share the authors' concern that the more ambitious expectations for brain imaging will have negative clinical, legal, and social consequences. Because we agree with these points, we will focus on our differences.

Davis et al. argue that brain imaging approaches to pain have failed to account for the fundamental core of pain, which they call “ouch.” Ouch is produced by a biological on/off switch that allows or blocks “the core of the pain experience.” Thus, ouch is most easily understood as the experience and expression that accompanies reflex withdrawal in response to a noxious stimulus. This is raw, immediate, and not yet elaborated as the more complex experience of pain. This idea of ouch recalls the debate about the minimal necessary neurological apparatus for pain experience and whether aversive behaviors in those without a fully developed cortex can be interpreted as “pain.” 1, 5 Ouch might bridge the distance between an experience of nothing and an experience of pain, with ouch being dependent on activity in subcortical rather than cortical circuits.