1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

101 Poster Chemosensory Coding and ClinicalOLFACTORY EVENT-RELATED BRAIN POTENTIALS TONEAR-THRESHOLD STIMULI IN HEALTHY ADULTSRamage E. 1 , Essoe J.K. 1 , Parks A.M. 1 , Hunt K. 1 , Lloyd K. 1 , GeislerM.W. 1 1 Psychology, San Francisco State University, San Francisco,CAIncreased amplitudes and shortened latencies of olfactory eventrelatedpotentials (OERP's) in response to supra-threshold stimuli havebeen correlated to behavioral odor threshold scores, however, thephysiological processing of near-threshold olfactory stimuli and therelationship to behavioral measures have not been examined. This studyused a modified single-stimulus paradigm measuring OERP's at midlineand ten global sites in response to odor stimuli presented in blockrandomization at slightly below-threshold (SBT), near-threshold (NT),and supra-threshold (ST) concentrations. Reaction time, odor intensityratings, behavioral odor thresholds and magnitude matchings of theodor stimuli to a series of weights, were collected in 16 male and 23female college students. Results indicate that: (1) the amplitudes forearly sensory olfactory information processing of the N1 and P2 ERPcomponents are similar for SBT and NT stimuli and greater for ST,while the timing, or latency, of the P2 and N2 ERP components aremore similar for SBT and NT stimuli with longer P2 and shorter N2latencies for ST, (2) the amplitudes for later cognitive olfactoryinformation processing of the P3 ERP component significantlyincreased as odor stimuli concentration increased and 3) amplitudeswere greatest in the frontal electrode sites for both N1 and N2components and greatest in the parietal electrode sites for both the P2and P3 components. Results suggest that the greatest difference betweenthe OERP's of NT and SBT stimuli are found during cognitiveinformation processing.102 Poster Chemosensory Coding and ClinicalCENTRAL OLFACTORY ACTIVITY TO DIFFERENT ODORINTENSITY IN OLDER PEOPLEWang J. 1 , Zimmerman E. 1 , Grunfeld R. 1 , Vesck J. 1 , Eslinger P.J. 2 , SmithM.B. 1 , Connor J.R. 3 , Yang Q.X. 1 1 Radiology, Pennsylvania StateUniversity, Hershey, PA; 2 Neurology, Pennsylvania State University,Hershey, PA; 3 Neurosurgery, Pennsylvania State University, Hershey,PADuring aging, human ability to evaluate odor intensity declines. Thepurpose of this study was using fMRI to examine the aging effect oncentral olfactory activity in response to different odor intensity. Theodor lavender (intensities 0.10%, 0.32%, and 1%) was presented to thenose with an olfactometer. The odor intensities used were determinedpsychophysically by another group of normal volunteers. The subjectswere asked to rate odor intensities using a scale of 0 to 10. Twelvesubjects (66.0 ± 10.9 years, 8 m, UPSIT score 33.3 ± 2.8) receivedfMRI at 3T. Ten of them provided complete pre-scan and after-scanevaluations of the odor intensities. While the subjective rating did notprovide significant difference between odor intensities (p > 0.11), fMRIshowed significant activation difference induced by different odorintensities (except between intensities 0.10% and 0.32%). Compared totwo weaker intensities, 1% lavender introduced significantly strongeractivation in the bilateral primary olfactory cortex, hippocampus, andentorhinal cortex (p < 0.001). These findings suggest that the decline ofthe ability to evaluate different odor intensities during aging is notcaused by the functional decay of the brain structures mentioned above.This study is supported in part by Leader Family Foundation and NIHR01 EB00454.103 Poster Chemosensory Coding and ClinicalREDUCTION OF MAGNETIC SUSCEPTIBILITY ARTIFACTSIN OLFACTORY FMRI WITH GESEPI-SENSE-EPI METHODZimmerman E. 1 , Wang J. 1 , Grunfeld R. 1 , Sun X. 1 , Vesck J. 1 , EslingerP.J. 2 , Smith M.B. 1 , Connor J.R. 3 , Yang Q.X. 1 1 Radiology, PennsylvaniaState University, Hershey, PA; 2 Neurology, Pennsylvania StateUniversity, Hershey, PA; 3 Neurosurgery, Pennsylvania State University,Hershey, PAThe severe magnetic susceptibility artifacts (signal loss andgeometric distortion) in the images of inferior brain areas pose adifficult challenge in conducting olfactory fMRI in these brain regions.To remove the artifacts for consistent olfactory fMRI mapping, wedeveloped the Gradient-Echo Slice Excitation Profile Imaging(GESEPI) technique. Combining the GESEPI with the state of artSENSE technology yields an effective method (GESEPI-SENSE-EPI)for olfactory fMRI with magnetic susceptibility artifact reduction. Theeffectiveness of GESEPI-SENSE-EPI in detection of olfactory fMRI inthe brain areas with severe artifacts was tested on nine human subjectswith GESEPI-SENSE-EPI and conventional EPI. The activationsdetected by the GESEPI-SENSE-EPI method in the base of the brainare in the areas of anterior olfactory nucleus and olfactory tubercles,which are impossible to see with conventional EPI. The success indetection of olfactory activation in these brain areas demonstrates thatthe GESEPI-SENSE-EPI is highly effective in artifact reduction andfMRI data acquisition. Supported by NIH RO1 EB00454.104 Poster Chemosensory Coding and ClinicalOLFACTORY TESTS IN THE DIAGNOSIS OF ESSENTIALTREMOR.Shah M. 1 , Findley L. 1 , Muhammed N. 1 , Hawkes C.H. 1 1 Smell & TasteResearch Unit, Essex Neuroscience Centre, London, United KingdomMost patients with tremor-dominant Parkinson´s disease (PD) haveimpaired smell function but it is unclear whether this is true for subjectswith essential tremor (ET). If ET patients do not exhibit meaningfulsmell loss, then olfactory testing may help to distinguish PD from ET.We assessed olfactory function of 59 ET and 64 PD patients using theUniversity of Pennsylvania Smell Identification Test (UPSIT) and theolfactory event-related potential (OERP). UPSIT scores were comparedto those from 245 healthy controls, and OERPs were compared to thosefrom 74 controls. Unlike the PD test scores, those of ET patients wereindistinguishable from controls when the effects of age, age of onset,gender, and smoking were taken into account. ET patients with a familyhistory of tremor scored significantly better than controls on the UPSIT,and their rate of decline with age was slower. The effect was notobserved on the OERP. This suggests that smell testing may help todistinguish between ET and tremor-predominant PD, and that patientswith a positive family history of tremor may represent a subgroupwhose olfactory function is enhanced by some unknown mechanism.26