Editorial

Sensory–motor incongruence and reports of ‘pain’ McCabe and colleagues [1] investigate the hypothesis that pain without obvious accompanying tissue damage might be caused by discordance between motor intent and movement [2]. According to that hypothesis, in the same way that motion sickness might result from discordant sensory input (from vestibular apparatus and proprioceptors), pain may result from changes in the cortical representation of somatic input, which falsely signals incongruence between motor intention and movement. That the central nervous system (CNS) detects such incongruence has long been established. The reafference principle [3], whereby an exact copy of the command for movement (the ‘efferent copy’) is subtracted from sensory input about the actual movement (‘reafference’) to yield an error signal (‘exafference’), and the corollary discharge model [4] are early examples. Since then, an impressive amount of researc