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NIDCD-Supported Research: Two Regions of Brain at Work in Tying Emotion, Intensity of Emotion to Experience
While one region of the brain is telling you whether you're experiencing something pleasant or unpleasant, a different region is letting you know just how pleasant or unpleasant, says a study published in the January 21, 2003, advance online version of Nature Neuroscience. Using functional magnetic resonance imaging (fMRI), a technique that graphically shows which parts of the brain are most active due to an increase in blood flow, NIDCD-supported researchers from Stanford University and the University of California, Berkeley, examined how two types of scents--an appealing, citrus-smelling scent and a repulsive, rancid-smelling scent--in mild and heavy doses would affect brain activity. The researchers found that the sheer pleasantness or unpleasantness of a scent is determined by the orbitofrontal cortex, in the front of the brain, while the amygdala, an almond-shaped structure in the brain's temporal lobe, determines the degree of pleasantness or unpleasantness. A person's emotional response to visual, auditory, and other sensory cues most likely takes place in the same brain regions, said the researchers, who chose the sense of smell for their study because it enabled them to independently alter the normally interwoven qualities of emotion and intensity of emotion most easily.