fMRI evidence for an inverted face representation in human somatosensory cortex.

We provide evidence that the face component of the somatosensory homunculus is actually upside down rather than right-side up along the central sulcus of the human brain. We pneumatically stimulated the forehead or chin of neurologically intact humans while acquiring fMRI images of somatosensory cortex. During forehead stimulation cortical regions along relatively inferior portions of the postcentral gyrus were most active whereas during chin stimulation relatively superior regions were most active. These data are consistent with an inverted face representation along the central sulcus of the human brain.