NEUROSCIENCE: Showing Up Emotions
Journal of Neuroscience 20, 7752 (2000).
Narrated by Peter R. Stern

Our senses are continuously bombarded with stimuli from the outside world. Some immediately arouse emotions such as pleasure, disgust, or fear and initiate behavioral responses aimed at seeking or avoiding continued exposure. To investigate the brain regions involved in processing emotional responses, Royet et al. presented the same individuals a range of pleasant, unpleasant, or neutral visual, olfactory, and auditory stimuli. Regional cerebral blood flow was measured by positron emission tomography. Emotionally charged stimuli caused increased activation of a core network of regions in the left hemisphere. The activated regions always included the orbitofrontal cortex, temporal pole, and superior frontal gyrus. The hypothalamus and the subcallosal gyrus were specifically activated by visual and olfactory stimuli, but not by auditory stimuli. Only emotionally charged smells, like lavender or mint, managed to activate the amygdala in both the left and right hemisphere. Thus there appears to be a core left hemispheric network of emotion processing regions that always gets activated in addition to other areas that appear to be specific for individual senses. -- PRS