Gender effects on odor-stimulated functional magnetic resonance imaging

• Published in: Brain research Vol. 818; no. 2; pp. 480 - 487
• Main Authors: Yousem, David M, Maldjian, Joseph A, Siddiqi, Faez, Hummel, Thomas, Alsop, David C, Geckle, Rena J, Bilker, Warren B, Doty, Richard L
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 13.02.1999; Amsterdam Elsevier; New York, NY
• Subjects: Adolescent; Adult; Analysis of Variance; Biological and medical sciences; Brain Mapping; Cerebral Cortex - pathology; Cortex; Female; Functional magnetic resonance imaging; Fundamental and applied biological sciences. Psychology; Gender effect; Humans; Magnetic Resonance Imaging - methods; Male; Odor; Odorants; Olfaction; Olfactory system and olfaction. Gustatory system and gustation; Sex Characteristics; Smell; Statistics, Nonparametric; Stimulation, Chemical; Vertebrates: nervous system and sense organs; Gender effect; Olfaction; Brain mapping; Cortex; Functional magnetic resonance imaging; Odor; Smell; Human; Cerebral cortex; Imaging; Central nervous system; Sex; Nuclear magnetic resonance imaging; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(98)01276-1

On standardized tests of odor identification and odor detection, women tend to score better than men at nearly all age groups. We sought to determine if these findings would translate to differences between the sexes in the volume of activated brain when odors are presented to subjects as the stimulants for functional magnetic resonance imaging (FMRI) experiments. The activation maps of eight right-handed women (mean age 25.3 years old, range 20–44, S.D. 8.3 years) were compared with those of 8 right-handed men (mean age 30.5, range 18–37, S.D. 6.5 years) given the same olfactory nerve stimuli in an FMRI experiment at 1.5 T. Olfactory stimuli were delivered to the patients in a passive fashion using a Burghart OM4-B olfactometer with a nose piece inserted into the patients' nostrils. We used agents (eugenol, phenyl ethyl alcohol, or phenyl ethyl alcohol alternating with hydrogen sulfide) that were selective for olfactory nerve stimulation in the nose. The odorants were delivered to both nostrils for 1 s every 4 s during a 30 s `on-period'. During the 30 s `off-period', the patient received room air at the same flow rate. The women's group-averaged activation maps showed up to eight times more activated voxels than men for specific regions of the brain (frontal and perisylvian regions). The left and right inferior frontal regions showed a statistically significant increase in activation in women at p<0.01. In general, more women showed activation than men. The results suggest that (1) FMRI activation maps in subject groups can demonstrate correlates to psychophysical tests of olfaction, and (2) one must control for gender when performing odor-stimulated FMRI experiments.