XVI International Symposium on Olfaction and Taste - ecro

<strong>XVI</strong> <strong>International</strong> <strong>Symposium</strong> on Olfaction and Taste
limonene and terpinenol). Responses were assessed by fMRI (1.5T -Siemens Sonata). Stimuli were delivered to the
subjects using an air-dilution olfactometer; after the functional scans, participants were to estimate intensity, pleasantness,
familiarity of the stimuli and the number of olfactory notes. Results showed that whereas the same intensity, pleasantness
and familiarity (p>.05 in all cases) were judged for low and high complexity odorants, the latter induced more olfactory
notes than the former (p=.015). A preliminary analysis performed on the imaging data using SPM8 revealed differential
piriform activation as a function of odorant molecular complexity. These findings suggest that complexity of odorant
molecules provides a framework to explain both the subjective experience of smells and its neural processing in the
olfactory cortex.
<strong>Symposium</strong> 23 “Evolution of chemosensory systems ” Wednesday 27 June
Olfactory evolution in Drosophila (EMBO Young Investigator Lecture)
Richard Benton
University of Lausanne, Center for Integrative Genomics, Lausanne, Switzerland
richard.benton@unil.ch
The detection of odours in the environment is universally important for primal behaviours such as feeding, mating, kin
interactions and escape responses. Moreover, animal olfactory systems display enormous evolutionary capacity, as
species acquire and discard olfactory receptor genes, neurons and behaviours in an ever-changing landscape of external
chemical stimuli. I will present our recent insights into olfactory system evolution yielded by analysis of a recently-
discovered family of olfactory receptors, the Ionotropic Receptors (IRs), and their neuronal circuits, in Drosophila.
Poster session I Poster #297
Neuroimaging of olfaction in obsessive-compulsive disorder
Heather A Berlin 1 , Cheuk Tang 2 , Johnny Ng 3 and Wayne Goodman 4
1 Mount Sinai School of Medicine, Psychiatry, New York, USA
2 Mount Sinai School of Medicine, Radiology; Psychiatry, New York, USA
3 Mount Sinai School of Medicine, Biomedical Engineering, New York, USA
4 Mount Sinai School of Medicine, Psychiatry; Neuroscience, New York, USA
heather.berlin@mssm.edu
Background: Obsessive-compulsive disorder (OCD) is a common psychiatric illness. Neuroimaging studies show that
compared to healthy controls (HCs), OCD patients have greater activation in their right insula to disgusting images.
OCD patients may in fact be more sensitive to unpleasant stimuli regardless of the sensory modality, which may trigger
their subsequent obsessions and compulsions. Therefore, we investigated the function of the olfactory system in response to
pleasant and unpleasant odors in OCD patients compared to HCs using functional magnetic resonance imaging (fMRI).
Methods: 7 OCD subjects and 8 matched HCs were exposed to pleasant (banana, vanilla, chocolate) and unpleasant
(garbage, feces, urine) odors using our specially developed olfactometer during fMRI. Unscented air was the control
stimulus. Subjects rated stimuli on intensity and valence and completed the UPSIT and a set of questionnaires measuring
OCD symptoms, disgust sensitivity, and emotion. Results: Compared to HCs, in response to unpleasant (vs. pleasant)
odors OCD patients had increased activation in their right anterior insular, left posterior insular, and anterior cingulate
cortex/superior cingulate; and decreased activation of their left lateral orbitofrontal cortex, left dorsolateral prefrontal
cortex, and putamen (bilateral). Conclusion: Similar to the results in the visual domain, people with OCD appear to be
more “neurally sensitive” to unpleasant odors. Their decreased activation in prefrontal regions in response to unpleasant
odors implies that they have less cognitive/top-down control over their increased unpleasant feelings (indicated by
increased insula and cingulate activation). This is the first study to examine olfaction in OCD using fMRI and further
elucidates the neural underpinnings of OCD, which may contribute to the development of better methods of treatment.
These results warrant further studies with larger sample sizes and other anxiety disorder comparison groups.
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