XVI International Symposium on Olfaction and Taste - ecro

<strong>XVI</strong> <strong>International</strong> <strong>Symposium</strong> on Olfaction and Taste
Delwart Contributed <strong>Symposium</strong> - Higher olfactory processing Tuesday 26 June
Mouse olfactory peduncle: core structure
Peter C Brunjes 1
1 University of Virginia, Psychology, Charlottesville, VA, USA
brunjes@virginia.edu
The olfactory bulb processes odor information detected in the nasal cavity. The area just behind the olfactory bulb is
known as the olfactory peduncle. It contains the rostral-most portion of the olfactory cortex (a region often referred to as
the anterior olfactory nucleus) as well as two smaller areas. The peduncle is traversed by two large tracts. The first is the
lateral olfactory tract (LOT), composed primarily of axons extending posteriorly from the bulb to the cortex. The second,
found in the core of the peduncle, is the “anterior limb of the anterior commissure”. This complex tract contains axons
coursing anteriorly from a variety of sources, including processes from the contralateral olfactory cortex (that cross in the
anterior commissure), fibers from more posterior portions of the ipsilateral olfactory cortex, and diverse fibers entering
the tract from the medial forebrain bundle and other areas (e.g., noradrenergic, cholinergic, histaminergic, orexinergic and
serotonergic axons). The purpose of the present study was to characterize this deep white matter region and to compare it
with an earlier examination of the LOT (Brunjes et al., J. Comp. Neurol. 519, 2011). Reconstructions of the tract from an
anterior and a posterior region of the peduncle were produced at 800X via electron microscopy. Every myelinated axon
in the two areas was outlined, yielding a total data set of almost 87,000 profiles. This population was then sampled to
visualize the distribution of the largest and smallest caliber axons and profiles with an elongated shape (and thus
travelling obliquely to the plane of section). While local areas exhibited differences in each of these categories, no large
scale patterns of organization were observed. Mean axon caliber was significantly higher in the anterior region of the
peduncular core, and profiles seen in both regions were smaller than those observed in the LOT. Supported by Grant
DC000338 from NIH (NIDCD).
Poster session II Poster #298
Olfactory performance of patients suffering from autism spectrum disorders (ASD)
Yvonne Brünner 1 , Tanja Michel 2 , Dagmar Honnef 1 , Martin Wiesmann 1 and Jessica Freiherr 1
1RWTH Aachen, Clinic for Diagnostic and Interventional Neuroradiology, Aachen, Germany
2RWTH Aachen, Clinic for Psychiatry, Psychotherapy and Psychosomatic, Aachen, Germany
ybruenner@ukaachen.de
Autism spectrum disorders (ASD) are clinically characterized by a triad of symptom clusters, namely challenges in social
interaction and communication as well as repetitive behaviors. Furthermore, ASD represents an innate and
neurodevelopmental psychiatric disorder with dysfunctional sensory perception and neural processing. Changes in
chemosensory function have been identified in several neurodegenerative or psychiatric disorders, like Parkinson’s and
Alzheimer’s disease or depression. Knowledge about chemosensory function in adult ASD patients is sparse due to a
small number of patients included in studies and a limited number of different olfactory subtests that have been carried
out. Taken together, it is difficult to draw comprehensive conclusions from the existing studies. Therefore, our aim was to
compare olfactory performance of 30 adult ASD patients with 30 age- and gender-matched healthy control subjects. Two
independent clinicians made the diagnosis. Furthermore, patients underwent a concise battery of psychological tests
including the Autism Diagnostic Observation Schedule (ADOS). We obtained olfactory performance scores by using the
Sniffin’ Sticks threshold test (n-butanol), odor discrimination test, and identification test (MONEX-40) as well as
pleasantness and intensity ratings. Our results suggest that olfactory sensitivity and olfactory pleasantness evaluation is
diminished in patients suffering from ASD compared to healthy control subjects. Even after exclusion of patients that
were smoking, taking medication, or suffering from comorbidities and their corresponding control subjects these results
are stable. It is suggested that the decline in olfactory sensitivity and pleasantness ratings are distinguishing
characteristics of ASD patients in comparison to healthy controls. The potential of using olfactory performance scores as
future biomarkers will be discussed.
Funding for this study was provided by the Medical Faculty of the RWTH Aachen.
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