title: Body position-dependent shift in odor percept present only for perithreshold odors.
abstract: We recently demonstrated that a supine position causes a decrease in olfactory sensitivity compared with an upright position. We pursued that initial finding in 3 separate experiments in which we explored the extent of, and mechanism underlying, this phenomenon. In Experiment 1, we replicated the decrease in olfactory sensitivity when in a supine compared with an upright position. In Experiment 2, we measured body position-dependent shifts in physiological variables and sniff measures while smelling suprathreshold odorants and performing a perithreshold odor intensity discrimination task. Olfactory performances were reduced while supine. However, no relationships between the shift in olfactory performances and either the physiological variables or sniff measures were found. In Experiment 3, we determined that there were no position-dependent shifts in ability to discriminate or identify suprathreshold odors or rate them for pleasantness, intensity, or familiarity. However, a drop in scores was observed, and performance was slowed, on a cognitive skill while supine. These results demonstrate a body position-dependent shift in olfactory sensitivity only for perithreshold odors that appears to be mediated by cognitive rather than physiological factors. Implications for olfactory imaging studies are discussed.
authors.affiliation: Department of Psychology, McGill University, Montreal, Quebec, Canada. jlundstrom@monell.org
authors.forename: Johan N
authors.initials: JN
authors.lastname: Lundström
authors.forename: Julie A
authors.initials: JA
authors.lastname: Boyle
authors.forename: Marilyn
authors.initials: M
authors.lastname: Jones-Gotman
mesh_terms: D020001:1-Butanol / Q000737:chemistry; D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000503:physiopathology / Q000523:psychology; D001794:Blood Pressure / Q000502:physiology; D003071:Cognition / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009812:Odorants; D010626:Phenylethyl Alcohol / Q000737:chemistry; D011187:Posture / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012684:Sensory Thresholds / Q000502:physiology*; D012727:Sex Characteristics; D012903:Smell / Q000502:physiology*; D016683:Supine Position / Q000502:physiology
chemical_list: D020001:1-Butanol; D010626:Phenylethyl Alcohol