PT - JOURNAL ARTICLE AU - R K Fulbright AU - P Skudlarski AU - C M Lacadie AU - S Warrenburg AU - A A Bowers AU - J C Gore AU - B E Wexler TI - Functional MR imaging of regional brain responses to pleasant and unpleasant odors. DP - 1998 Oct 01 TA - American Journal of Neuroradiology PG - 1721--1726 VI - 19 IP - 9 4099 - http://www.ajnr.org/content/19/9/1721.short 4100 - http://www.ajnr.org/content/19/9/1721.full SO - Am. J. Neuroradiol.1998 Oct 01; 19 AB - BACKGROUND AND PURPOSE Odors can elicit a range of behaviors and emotions. Our purpose was to identify regional activation of the human cerebral cortex in response to pleasant (positive hedonic value) and unpleasant (negative hedonic value) odors.METHODS Thirteen neurologically normal adults underwent functional MR imaging of frontal and anterior temporal brain regions with a gradient-echo echo-planar technique. Eleven candidate regions of interest (ROIs) were identified on the first half of the data set based on t-map comparisons of signal intensities during administration of clementine (pleasant odor), isovaleric acid (unpleasant odor), and clear air (control odor). These ROIs were applied to the second half of the data set, and the number of voxels activated with the odorants was compared with the number of voxels activated during clear air trials, using independent t-tests.RESULTS Clementine activated five cortical areas: Brodmann's area (BA) 8, BA 32 (lateralized to left), BA 46/9, BA 6 (lateralized to right), and the insula. Isovaleric acid activated four of the five regions without lateralization; no BA 8 activity was seen. Clementine produced more activity than isovaleric acid in the left insula, and isovaleric acid produced more activity than clementine in the left BA 6. No activation was detected in the orbitofrontal cortex or in the medial temporal lobes. Subjects rated clementine, isovaleric acid, and clear air as being pleasant, unpleasant, and neutral, respectively.CONCLUSION Activation in frontal regions may represent brain processes linked to olfactory networks. There may be regional specialization based on odorant hedonic values.