title: Olfactory-visual integration facilitates perception of subthreshold negative emotion.
abstract: A fast growing literature of multisensory emotion integration notwithstanding, the chemical senses, intimately associated with emotion, have been largely overlooked. Moreover, an ecologically highly relevant principle of "inverse effectiveness", rendering maximal integration efficacy with impoverished sensory input, remains to be assessed in emotion integration. Presenting minute, subthreshold negative (vs. neutral) cues in faces and odors, we demonstrated olfactory-visual emotion integration in improved emotion detection (especially among individuals with weaker perception of unimodal negative cues) and response enhancement in the amygdala. Moreover, while perceptual gain for visual negative emotion involved the posterior superior temporal sulcus/pSTS, perceptual gain for olfactory negative emotion engaged both the associative olfactory (orbitofrontal) cortex and amygdala. Dynamic causal modeling (DCM) analysis of fMRI timeseries further revealed connectivity strengthening among these areas during crossmodal emotion integration. That multisensory (but not low-level unisensory) areas exhibited both enhanced response and region-to-region coupling favors a top-down (vs. bottom-up) account for olfactory-visual emotion integration. Current findings thus confirm the involvement of multisensory convergence areas, while highlighting unique characteristics of olfaction-related integration. Furthermore, successful crossmodal binding of subthreshold aversive cues not only supports the principle of "inverse effectiveness" in emotion integration but also accentuates the automatic, unconscious quality of crossmodal emotion synthesis.
authors.affiliation: Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32304, USA. Electronic address: lnovak@fsu.edu.
authors.forename: Lucas R
authors.initials: LR
authors.lastname: Novak
authors.affiliation: Department of Neurology, Northwestern University Feinberg School of Medicine, USA.
authors.forename: Darren R
authors.initials: DR
authors.lastname: Gitelman
authors.affiliation: Waisman Center for Brain Imaging and Behavior, University of Wisconsin-Madison, USA.
authors.forename: Brianna
authors.initials: B
authors.lastname: Schuyler
authors.affiliation: Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32304, USA. Electronic address: wenli@psy.fsu.edu.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D003463:Cues; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D055696:Olfactory Perception / Q000502:physiology*; D046709:Pattern Recognition, Physiological / Q000502:physiology*; D010812:Physical Stimulation; D012119:Respiration; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: Emotion; FMRI; Multisensory integration; Olfaction; Vision