Abstracts - Association for Chemoreception Sciences

#P65 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
#P66 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Perception and encoding of odor elements and mixtures
in the human brain
Keng Nei Wu 1 , Sydni M. Cole 1 , Jay A. Gottfried 1,2
1
Northwestern University/Neurology Department, Feinberg School of
Medicine Chicago, IL, USA, 2 Northwestern University/Department of
Psychology Evanston, IL, USA
In the natural environment, most odorous objects are composed
of dozens, if not hundreds, of volatile molecules. Despite
this apparent complexity, the olfactory system seamlessly
integrates these components into perceptual wholes. Utilizing
a between subject design, this experiment aimed to investigate
how experience in the form of aversive learning modulates
perception and encoding of odor mixtures by pairing either a
target binary odor mixture (Mx) or one of its components (Ele)
with an electric shock. We used psychophysical measurements,
functional magnetic resonance imaging (fMRI), and multivariate
analytical techniques to investigate these learning induced
changes. We presented human subjects with six stimuli: three
monomolecular odorants (A, B, C), and three binary mixtures
(AB, BC, AC). To date, results have been collected for 13 subjects
(8 Ele, 5 Mx) who were successfully conditioned. When asked to
identify the odor component(s) of these stimuli, subjects in the
Mx group showed decreased accuracy in identifying the correct
component(s). Moreover, these subjects also rated mixtures to be
less similar to their components, while subjects in the Ele group
rated mixtures to be more similar to their components after
conditioning. These preliminary findings suggest that olfactory
learning of a binary mixture may induce perceptual and neural
fusion of odor elements into a synthetic whole. Conversely,
pairing a shock with a component of a binary mixture may
induce neural “fission” of the mixture, such that its components
are processed in a more elemental fashion. Ongoing fMRI
analysis will test the hypothesis that learning induced changes
in odor quality perception may be reflected in the correlation
between odor evoked patterns of activation in the posterior
piriform cortex. Acknowledgements: This work was supported
by Northwestern Institutional Predoctoral Training Awards
to K.N.W. (T32NS047987) and grants R01DC010014 and
K08DC007653 from the US National Institute on Deafness and
Other Communication Disorders to J.A.G.
The Fate of the Inner Nose: Odor Imagery in Patients With
Olfactory Loss
Elena L. R. Flohr 1,2 , Artin Arshamian 3,1 , Matthias J. Wieser 2 , Cornelia
Hummel 1 , Maria Larsson 3 , Andreas Muehlberger 2 , Thomas Hummel 1
1
Smell and Taste Clinic, University of Dresden Medical School Dresden,
Germany, 2 Department of Psychology I, University of Würzburg
Wuerzburg, Germany, 3 Department of Psychology, Stockholm
University Stockholm, Sweden
Although the concept of olfactory mental imagery remains
controversial, recent studies support the principle. Cerebral
activations during olfactory mental imagery are fairly well
investigated in healthy participants but very few studies
address the subjects of olfactory imagery in patients with
olfactory loss. To investigate if olfactory imagery is impaired
in patients who are no longer able to smell, 16 participants
with acquired anosmia and 19 normosmic control participants
have been investigated. We used functional magnet resonance
tomography and subjective ratings to explore the mechanisms
during mental imagery of odors. After an imagery training,
participants imagined odors triggered by words naming pleasant
and unpleasant olfactory objects. We found that the patients
compared to healthy control participants showed greater
difficulties in imagining odors and lower intensity scores while
doing so. Looking at neural activation, the pattern observed
by Bensafi et al. (2007) that imagining unpleasant odors leads
to more activation in olfaction-related areas than imagining
pleasant odors was found in the control group but not in the
anosmic group. This hedonic specific approach was meant to
control for activation that was due to attention allocation or
activation of semantic circuits that are alone sufficient to evoke
activation in olfactory areas. Direct comparisons between the
groups revealed greater activation in the anosmic group in
olfactory areas than in the control group. We conclude that,
in contrast to the control group, anosmic participants have
difficulties to perform olfactory imagery in the conventional
meaning.
#P67 POSTER SESSION II:
OLFACTION DEVELOPMENT; TASTE CNS;
NEUROIMAGING; OLFACTION CNS
Multi-modal functional imaging of rat olfactory bulb with
orthonasal and retronasal odorant stimulation: functional
insights through complementary techniques
Michelle R Rebello 1,2 , Basavaraju G Sanganahalli 3 , Gordon M
Shepherd 1,2 , Fahmeed Hyder 3 , Justus V Verhagen 1,2
1
The John B. Pierce Laboratory New Haven, CT, USA, 2 Yale School of
Medicine, Dept. Neurobiology New Haven, CT, USA, 3 Yale University,
MRRC New Haven, CT, USA
POSTER PRESENTATIONS
Various techniques can be used to evaluate odor response maps
of the olfactory bulb, each with its own advantages. Here we
combined fMRI with intrinsic and calcium optical imaging to
Abstracts are printed as submitted by the author(s).
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