Re-examination of the human taste region: a positron emission tomography study

There is considerable uncertainty regarding the cortical areas in the human brain that are involved in gustatory processing. Evidence from nonhuman pr imates indicates that parts of the peri-central opercular region (secondary somatosensory cortex) and insular cortex may be important for gustatory pr ocessing. The aim of the study was to examine changes in cerebral blood flo w during gustatory stimulation (with sucrose or water) in the insulo-opercu lar region of the human brain with positron emission tomography using only movement of the tongue and mouth as control conditions. This is important b ecause subtractions of responses to one gustatory stimulus from those to an other may mask gustatory activity that is common to both stimuli, even when the control stimulus is an apparently tasteless one (e.g. water). Bilatera l increases in activity were observed in the insulo-opercular region and, c onsistent with animal work, they indicate that there are a number of separa te foci within this general area where primary gustatory inputs may be proc essed.