title: Methods for olfactory fMRI studies: Implication of respiration.
abstract: Human olfactory system is under-studied using fMRI compared with other sensory systems. Because the perception (intensity, threshold, and valence) and detection of odors are tightly involved with respiration, the subject's respiration pattern modulates and interacts with the experimental paradigm, which presents difficulties for olfactory fMRI data acquisition, post-processing, and interpretation. Based on our investigation on the interactions of odor presentation and subject's respiration, we propose a respiration-triggered event-related olfactory fMRI technique and a data post-processing method that effectively captures precise onsets of olfactory blood-oxygen-level-dependent (BOLD) signal in the primary olfactory cortex. We compared the olfactory BOLD signals from seventeen normal healthy adults with diverse respiratory patterns and showed that the subjects' respiratory patterns modulated the olfactory stimulation paradigm, which significantly confounded the BOLD signal. The presented experimental technique provides a simple and effective means for generating reliable olfactory fMRI results.
authors.affiliation: Departments of Radiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Jianli
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Sun
authors.forename: Qing X
authors.initials: QX
authors.lastname: Yang
mesh_terms: D000328:Adult; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009812:Odorants; D066194:Olfactory Cortex / Q000502:physiology*; D009833:Olfactory Pathways / Q000502:physiology; D055696:Olfactory Perception / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010812:Physical Stimulation; D012119:Respiration; D012815:Signal Processing, Computer-Assisted
chemical_list: D010100:Oxygen
keywords: BOLD signal; fMRI; odor stimulation; olfaction; olfactory activation; respiration