Abstracts - Association for Chemoreception Sciences

women; mean age 23.4 years; range 20-29 years) were examined.
Normal olfactory function was ascertained using the “Sniffin
Sticks”. All subjects rated peach odor as pleasant, and the smell
of butanol as unpleasant. According to their hedonic judgement
of liquorice odor, subjects were divided into two groups: group
1 subjects described the odor of liquorice as pleasant, and group
2 subjects experienced liquorice as unpleasant. Functional
magnetic resonance imaging (fMRI) was used to compare the
cerebral activations while smelling the three different odors:
pleasant peach, unpleasant butanol, and ambiguous liquorice.
Analysis indicated common neural activations in response to
all odors in a number of regions, e.g. in cingulate gyrus, medial
frontal gyrus and caudate nucleus. In subjects disliking liquorice,
activations were found in four areas including medial frontal
gyrus, postcentral gyrus and medial temporal gyrus. In liquoriceliking
subjects, activations were found in the medial frontal
lobe. These results suggest that there are different patterns of
central nervous activation dependent on the hedonic value of an
odor, mainly including the frontal lobe, with unpleasant odors
activating the more lateral frontal lobe and pleasant odors more
medial areas. In addition, unpleasant odors produced more
activation as compared to pleasant odors. Acknowledgements:
Supported by Takasago, Paris.
#P57 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Valence Modulation of Crossmodal Olfactory-Visual
Neural Integration
Jessica Freiherr 1 , Anna-Nora zur Nieden 1 2, 3, 4
, Johan N. Lundström
1
RWTH Aachen University, Diagnostic and Interventional
Neuroradiology Aachen, Germany, 2 Monell Chemical Senses Center
Philadelphia, PA, USA, 3 University of Pennsylvania, Department of
Psychology Philadelphia, PA, USA, 4 Karolinska Institute, Department
of Clinical Neuroscience Stockholm, Sweden
We recently demonstrated that a concurring congruent visual
stimulus does not affect olfactory sensitivity but does modulate
the perceived valence or pleasantness and intensity of an odor.
However, the congruency-dependent effect occurred only for
odors perceived as pleasant. With the current study we explored
the neural mechanisms of this behavioral phenomenon with
the aim of determining the influence of valence on the neural
correlates of crossmodal olfactory-visual integration. To this
end, the pleasant odor phenyl ethyl alcohol and unpleasant odor
isovaleric acid was applied using constant-flow olfactometry
in combination with a congruent, incongruent, or blank visual
stimulus during an event-related fMRI paradigm. As control
stimuli we also applied pleasant and unpleasant visual stimuli
and a baseline stimulus. We investigated brain activation due to
crossmodal integration in 14 healthy, normosmic participants.
Subjects had to rate pleasantness of the odors after each
event. Statistical analyses of the behavioral data demonstrate
a replication of the aforementioned findings. As predicted,
valence-independent olfactory-visual integration was mediated
by low-level multisensory integration areas in the superior
parietal lobule. Preliminary analyses of the fMRI data indicate
that valence-dependent integration occurs in higher-order
multisensory integration areas in conjunction with areas known
to code for odor valence. Moreover, a differential processing
of unpleasant compared to pleasant olfactory-visual stimulus
combinations has been established. Further insights into the
neural processes mediating the influence of valence on the
neural correlates of olfactory-visual integration will be discussed.
Acknowledgements: Funded by a startup grant from the Medical
Faculty of RWTH Aachen University.
#P58 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Visuo-olfactory integration facilitates peri-threshold
olfactory categorization
Jaryd Hiser 1 , Lucas R. Novak 1 , Wen Li 1,2
1
Department of Psychology, University of Wisconsin - Madison
Madison, WI, USA, 2 Waisman Center, University of Wisconsin -
Madison Madison, WI, USA
Olfactory quality discrimination and categorization proves
a highly challenging process in humans. Additional information
from other senses, such as visual cues, may facilitate this
operation via crossmodal integration. To date, crossmodal
sensory integration has focused on non-chemical senses. Using
functional magnetic resonance imaging (fMRI) techniques,
this study characterized visuo-olfactory integration in olfactory
categorization. Participants (N=29) smelled an odor at a merely
detectable level from one of three categories (food, floral, or
wood) while viewing a picture that was congruent or incongruent
to the odor, and then made a category decision on the odor.
Reaction time (RT) was faster for congruent versus incongruent
stimuli (P