Browsing by Author "Chen, Denise"

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    Binaral Rivalry in the Presence of Visual Perceptual and Semantic Influences
    (Public Library of Science, 2012) Chen, Jennifer; Zhou, Wen; Chen, Denise
    When two different odorants are presented simultaneously to the two nostrils, we experience alternations in olfactory percepts, a phenomenon called binaral rivalry. Little is known about the nature of such alternations. Here we investigate this issue by subjecting unstable and stable olfactory percepts to the influences of visual perceptual or semantic cues as participants engage in simultaneous samplings of either two different odorants (binaral) or a single odorant and water (mononaral), one to each nostril. We show that alternations of olfactory percepts in the binaral setting persist in the presence of visual perceptual and semantic modulations. We also show that perceptual cues have a stronger effect than semantic cues in the binaral case, whereas their effects are comparable in the mononaral setting. Our findings provide evidence that an inherent, stimulus-driven process underlies binaral rivalry despite its general susceptibility to top-down influences.
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    Human olfactory perception and olfactory communications of social information
    (2009) Zhou, Wen; Chen, Denise
    As one of the five basic senses, olfaction provides a unique channel to understand our sensory world and socioemotional experiences. It is phylogenetically old, highly conserved in evolution, and ubiquitously employed in the animal kingdom to communicate identity and motivation. Nevertheless, compared to vision and audition, human olfaction is poorly researched. Here six studies were conducted to probe the sensory properties of human olfactory system and its role in socioemotional communication. Study I examined whether sensory rivalry, as in binocular rivalry, also exists in the olfaction system. Study II looked at the influence of smells on visual perception. Study III tested the effect of chemosensory fearful cues on visual emotional perception. Study IV tested people's ability to detect chemosensory emotional cues and the role of familiarity in their sensitivity to such cues. Study V correlated one's chemosensory ability with his/her emotional capacity to probe the behavioral linkages between human olfaction and emotion. Lastly, Study VI examined the neural correlates of the social nature of natural human body odors by using a group of subjects with various degrees of social anxiety. The results demonstrate that there can be rivalry in olfactory processings between the two nostrils and in the cortex, and olfactory processings interact with visual processings. In addition, olfaction and emotion are closely related to each other. The olfactory system processes the socioemotional information conveyed by natural human body odors, which influences people's behavior and emotional processings, but often without their subjective awareness.
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    Human Olfactory Perception: Characteristics, Mechanisms and Functions
    (2013-09-16) Chen, Jennifer; Pomerantz, James R.; Chen, Denise; Logan, Jessica M.
    Olfactory sensing is ubiquitous across animals and important for survival. Yet, its characteristics, mechanisms, and functions in humans remain not well understood. In this dissertation, I present four studies on human olfactory perception. Study I investigates the impact of short-term exposures to an odorant on long-term olfactory learning and habituation, while Study II examines human ability to localize smells; Study III probes visual-olfactory integration of object representations, and Study IV explores the role of olfaction in sensing nutrients. Several conclusions are drawn from these studies. First, brief intermittent exposures to even a barely detectable odorant lead to long-term incremental odorant-specific habituation. Second, humans localize smells based on gradient cues between the nostrils. Third, there is a within-hemispheric advantage in the integration of visual-olfactory object representations. Fourth, olfaction partakes in nutrient-sensing and facilitates the detection of food. Some broader implications of our findings are discussed.
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    Nostril-Specific Olfactory Modulation of Visual Perception in Binocular Rivalry
    (The Society for Neuroscience, 2012) Zhou, Wen; Zhang, Xiaomeng; Chen, Jennifer; Wang, Li; Chen, Denise
    It is known that olfaction and vision can work in tandem to represent object identities. What is yet unclear is the stage of the sensory processing hierarchy at which the two types of inputs converge. Here we study this issue through a well established visual phenomenon termed binocular rivalry. We show that smelling an odor from one nostril significantly enhances the dominance time of the congruent visual image in the contralateral visual field, relative to that in the ipsilateral visual field. Moreover, such lateralization-based enhancement extends to category selective regions so that when two images of words and human body, respectively, are engaged in rivalry in the central visual field, smelling natural human body odor from the right nostril increases the dominance time of the body image compared with smelling it from the left nostril. Semantic congruency alone failed to produce this effect in a similar setting. These results, taking advantage of the anatomical and functional lateralizations in the olfactory and visual systems, highlight the functional dissociation of the two nostrils and provide strong evidence for an object-based early convergence of olfactory and visual inputs in sensory representations.
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    Right fusiform differentiates natural human sweat of sexual arousal from its non-social control
    (2007) Zhou, Wen; Chen, Denise
    Intraspecific chemical communications are documented in animals from single-celled organisms to nonhuman mammals. Increasing behavioral studies and recent brain imaging studies using positron emission tomography point to the existence of chemical communications in humans. Using functional magnetic resonance imaging, we examined whether the brain differentiates between human-related smells (sweat of sexual arousal, sweat of neutral emotion, and putative human sex pheromone androstadienone) and their non-social control (phenyl ethyl alcohol or PEA) after controlling for differences in the perceived intensity and pleasantness of the smells. With PEA as the reference point, we identified a region in the right fusiform gyrus which showed strong activation to the sweat of sexual arousal and little response to the putative sex pheromone. Our result suggests the right fusiform recognizes the human quality associated with the sweat of sexual arousal. Keywords. Chemical communication, fMRI, fusiform, human body odor