AVERSIVE GUSTATORY STIMULATION ACTIVATES LIMBIC CIRCUITS IN HUMANS

Animal studies implicate the amygdala and its connections in the recog nition of aversive stimuli, A recent PET study demonstrated that the h uman amygdala and left orbitofrontal cortex show substantial increases in regional cerebral blood how (rCBF) during exposure to aversive odo urants, To examine if aversive gustatory stimuli similarly activate th ese regions, nine healthy women tasted an aversive saline solution, pu re water and chocolate while rCBF was measured with PET. The aversive saline condition, when contrasted with the water condition, increased activity in the right amygdala, left anterior orbitofrontal cortex, me dial thalamus, pregenual and dorsal anterior cingulate, and the right hippocampus. The right amygdala, left orbitofrontal cortex and pregenu al cingulate remained significantly activated when saline was compared with chocolate, The present results indicate that the amygdala and or bitofrontal cortex respond to aversive stimuli in both the olfactory a nd gustatory modalities, and highlight the role of the pregenual cingu late in negative emotional processing.