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1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

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377 Slide Clinical <strong>Chemosensory</strong>COMPUTATIONAL MODELING OF NASAL AIRFLOW ANDODORANT TRANSPORT IN PATIENTS WITH CHRONICRHINOSINUSITISZhao K. 1 , Cowart B.J. 1 , Pribitkin E.A. 2 , Rawson N.E. 1 , Rosen D. 2 ,Scherer P.W. 3 , Klock C.T. 1 , Vainius A.A. 1 , Dalton P. 1 1 MonellChemical Senses Center, Philadelphia, PA; 2 Otolaryngology-Head &Neck Surgery, Thomas Jefferson University, Philadelphia, PA;3 Bioengineering, University of Pennsylvania, Philadephia, PAMechanical obstruction of odorant flow to olfactory receptor sites islikely one of the primary causes of olfactory loss in chronicrhinosinusitis (CRS) patients, in addition to other possible pathologicalmechanisms. However, quantifying the functional impact of variousnasal obstructions and the subsequent treatment outcomes usingacoustic rhinometry (AR), rhinomanometry (RM) or CT scans isuninformative: numerous studies have shown a poor correlationbetween conventional measurements and patients´ subjective symptomsor measures of psychophysical performance. In this preliminary study,8 CRS patients were assessed using AR, RM and CT scans, and theirodor identification and olfactory thresholds (to carvone, d-limonene andphenethyl alcohol) were also obtained. Using computational fluiddynamics techniques, we converted each patient´s CT scans into ananatomically accurate 3-D numerical nasal model that was used tosimulate nasal airflow and predict odorant delivery rates to the olfactoryepithelium. The accuracy of the models were verified by comparingmodel predictions with measured nasal resistance, airflow rates,pressure drops, area-distance function, etc. Variations in measuredolfactory sensitivity were then correlated with differences of nasalairflow and odorant delivery rates to olfactory neuroepithelium. Ourultimate goal is to quantitatively reveal the underlying conductivemechanisms contributing to olfactory loss in CRS that cannot bedetermined using the existing tools. In the future, such modelingtechniques may provide quantitative evaluation of treatment for CRSand an important pre-treatment guide to optimize airflow and odorantdelivery in human nose. NIH P50 DC006760378 <strong>Symposium</strong> Presidential: Why Have Neurogenesis inAdult Olfactory Systems?ADULT NEUROGENESIS IN THE MAMMALIAN BRAINGould E. 1 1 Psychology, Princeton University, Princeton, NJThe hippocampus undergoes substantial neurogenesis in adulthood—in the young adult rat many thousands of new neurons are producedeveryday. Adult neurogenesis in the hippocampus has been observed inmany mammalian species, including humans. The formation of newneurons in this brain region is affected by hormones and experience.Numerous forms of stress, including exposure to predator odor, havebeen shown to exert a negative influence on cell proliferation in thehippocampus. On the other hand, enriched environments, learning andphysical activity have a positive effect on the number of new neurons.These findings suggest potential roles for adult neurogenesis. Since thehippocampus is important for certain types of learning and memory, aswell as for anxiety and stress regulation, new neurons may participate inthese functions.379 <strong>Symposium</strong> Presidential: Why Have Neurogenesis inAdult Olfactory Systems?THE OLFACTORY PATHWAY OF DECAPOD CRUSTACEANS—A MODEL FOR LIFE-LONG NEUROGENESISSchmidt M. 1 1 Biology, Georgia State University, Atlanta, GADecapod crustaceans are similar to vertebrates in having life-longneurogenesis in both the peripheral and central olfactory pathways.Work from various labs over the last decade has revealed that incrustaceans adult neurogenesis in the olfactory organ occurs as a slow“longitudinal” turnover and net addition of receptor units whereas in thecentral olfactory pathway it mainly consists of a slow, continuousaddition of neurons. Compared to the situation in the vertebrateolfactory bulb, adult neurogenesis in the central olfactory pathway ofcrustaceans shows similarities but also distinct differences. Mostnotable among the similar features is the susceptibility of crustaceanadult neurogenesis to a host of external and internal parameters, such asafferent input, serotonin level, season of the year, environmentalrichness, and social status. In contrast to the vertebrate situation, thepredominant neuron type produced in adult crustacean brains areprojection neurons, while new local interneurons are generated in lowernumber and only in some species. Furthermore, recent studies indicatethat in crustaceans very few neuroblasts serve as neuronal stem cellswhereas in the vertebrate olfactory bulb new neurons originate frommore numerous astroglia-like precursors. Further analysis of adultneurogenesis in decapod crustaceans will reveal more about itsunderlying cellular mechanisms and its functions in olfactoryinformation processing. Comparing these data with the situation invertebrates might ease identification of fundamental principles in thelayout of the olfactory pathway that are served by and thus require adultneurogenesis.380 <strong>Symposium</strong> Presidential: Why Have Neurogenesis inAdult Olfactory Systems?SENSORY ENRICHMENT, NEUROGENESIS ANDOLFACTORY LEARNING IN AN ADULT INSECTCayre M. 1 1 Centre National de la Recherche Scientifique, MarseilleCedex9, FranceIn the adult cricket brain, new neurons are being produced throughoutthe insect´s life. This neurogenesis occurs in the main integrativecenters of the insect brain, the mushroom bodies (MB), where theneuroblasts responsible for their formation persist after the imaginalmoult. The rate of production of new neurons is controlled not only byinternal cues such as morphogenetic hormones (juvenile hormone andecdysone) but also by environmental cues. Crickets reared in a sensoryenriched environment presented an increase in neuroblast proliferationas compared to crickets reared in an impoverished environment.Conversely, unilateral sensory deprivation led to reduced neurogenesisin the mushroom body ipsilateral to the lesion. In search of a functionalrole for the new cells, we specifically destroyed mushroom bodyneuroblasts in young adults by gamma-ray irradiation of the head. Wedeveloped a learning paradigm adapted to the cricket, that we called"escape paradigm." Using this operant associative learning test, weshowed that crickets lacking neurogenesis exhibited delayed learningand reduced memory retention of the task, especially when olfactorycues were used. Our results suggest that environmental cues are able toinfluence adult neurogenesis and that in turn, newly generated neuronsparticipate to olfactory integration, optimizing learning abilities of theanimal, and thus its adaptation to its environment. However, we have toconsider and discuss that learning in insects cannot always be attributedto new-born brain neurons because in many insect species neurogenesisis completed during preimaginal stages. This work has been financiallysupported by the FYSSEN Foundation.95

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