1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

217 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalFMRI OF SUBTHRESHOLD INTEGRATION OF ODORS ANDTASTES: A STUDY OF LEARNED CONGRUENCYBreslin P.A. 1 , Galindo-Cuspinera V. 1 , Alarcon S.M. 1 , Lee W. 1 , ValdezJ. 2 , McGue C. 2 , Barrett F. 2 , Pratiwadi R. 2 , Tharp A.A. 1 , Tharp C. 1 ,Dalton P. 1 , Turetsky B. 2 , Loughead J. 2 1 Monell Chemical SensesCenter, Philadelphia, PA; 2 Psychiatry, University of Pennsylvania,Philadelphia, PASub-threshold integration of a congruous smell and taste pair, but notan incongruous smell and taste pair (Dalton et al., 2000), showed thatflavor perception might arise from the central neural integration of thismulti-modal input. One question that remained, however, was why anincongruous pairing of stimuli would fail to integrate. To determinewhether prior exposure played a role in summation of tastes and odors,we tested the sub-threshold integration of otherwise incongruous pairsof stimuli prior to, during, and following their three-weekadministration in gum form. Following exposure, the integrationthreshold for the exposure pair fell, demonstrating newly acquiredsummation, while the integration thresholds of combinations notexperienced during exposure remained constant. The failure of theincongruous taste and smell stimuli to integrate may be attributed to alack of prior experience with their pairings. fMRI of brain BOLD signalin subjects throughout the study reveal that subthreshold stimuli activatetraditional brain regions for taste and smell and show enhancedactivation when integrated. Supported in part by NIH DC02995 & P50DC0670 to PASB219 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and Trigeminal`ACTIVE´ TASTING SELECTIVELY ENHANCESPERCEPTION OF MSG ON THE FRONT OF THE TONGUEGreen B. 1 , Urban L. 1 1 The John B. Pierce Laboratory, New Haven, CTTasting is an active process that occurs in the context of mechanicalstimulation. The present study followed up our recent finding that activetasting enhanced perception of MSG more than other tastes, particularlyin the front of the mouth. In the prior study sucrose, NaCl and MSGwere swabbed onto the tongue tip or both the tongue tip and hard palate(which contains no taste buds), and taste intensity was rated afterpassively receiving the stimulus or touching the tongue to the roof ofthe mouth and swallowing once. Active tasting increased perception ofsucrose and MSG when stimulus was applied to both surfaces, butenhanced only perception of MSG when it was applied just to thetongue. Because MSG is perceived more strongly in the back of themouth, it was possible that swallowing caused MSG to spread toposterior taste areas. We tested this hypothesis by swabbing sucrose,NaCl, citric acid, QSO 4 and MSG onto the tongue tip and asking Ss (n =22) to rate taste intensity on the gLMS under two conditions: with thetongue immobile and after Ss said the word “taste” three times.Articulating “taste-taste-taste” produced mechanical stimulation at thetongue tip while limiting stimulus spread to the anterior hard palate. Thearticulation condition led to higher intensity ratings relative to thepassive condition only for the savory taste of MSG [F(4,168) = 2.78; p< 0.05]. This result rules out stimulus spread as the primary cause ofsavory taste enhancement during active tasting and implies thatenhancement is caused by a mechanical or tactile effect that is specificto perception of MSG. (Supported in part by NIH grant DC005002)218 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalHUMAN CORTICAL ACTIVITY OF TOUCH SENSATION ANDLATERALITYKobayakawa T. 1 , Gotow N. 1 , Toda H. 2 , Saito S. 1 1 Institute for HumanScience and Biomedical Engineering, National Institute of AdvancedIndustrial Science and Technology, Tsukuba, Ibaraki, Japan; 2 NationalInstitute of Advanced Industrial Science and Technology, Tsukuba,Ibaraki, JapanIn daily life, touch or texture sensation of food will always presentsimultaneously with taste or flavor. The interaction between touchsensation and gustation, however, is still little known. In order toinvestigate interaction, we tried to establish basic method forpresentation touch sensation that is suitable for evoked potential ormagnetic fields. Air puff or electric stimulation is generally used formeasuring evoked potential of touch sensation in hands or legs. In caseof measurement for tactile sensation of tongue, however, electrode willgive artifact to MEG sensors, because tongue is near to sensors.Additionally, air puff method will generate explosion noise atstimulation and will evoke auditory sensation simultaneously. In orderto solve these problems, we have developed new method, not puffingair but pulling tongue mucosa by utilizing vacuum chamber. Wesucceeded to obtain evoked magnetic fields without any artifact. Wepresented touch stimulation to right and left edge of participants´tongue, which was located about 2 cm from the center. We presentedtactile stimulus during 2 ms and average inter stimulus interval was twoseconds, which was randomized in range 1000 ms. 200 trials werepresented to each side, and sampling rate was 625 Hz. Clear magneticdistribution pattern was observed about 90 ms after stimulus, andestimated equivalent current dipoles (activated area) were located inbottom of central sulcus. More precise analyses are in progress.220 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalOVEREXPRESSION OF K+ CHANNEL SUBTYPES ALTERSRESPONSIVENESS TO FATTY ACIDS IN A CHEMOSENSORYCELL LINEShah B.P. 1 , Hansen D.R. 1 , Gilbertson T.A. 1 1 Biology & The Center forIntegrated BioSystems, Utah State University, Logan, UTOur studies in obesity-prone and –resistant rats suggest that the ratioof fatty acid-sensitive (fa-s) to fatty acid-insensitive (fa-i) delayedrectifying K + (DRK) channels contributes to differences in dietary fatpreference (Gilbertson et al. Physiol. Behav. 86:681, 2005). Usingheterologous expression, we have determined that the KCNA & KCNBDRK families are fa-s channels, while the KCNC family is fa-i. To testthe hypothesis that the ratio of fa-s:fa-i DRK channels alters fatty acidresponsiveness, we have attempted to overexpress a fa-i channel(KCNC1) or a fa-s channel (KCNA5) in an enteroendocrine cell line(STC-1) using lipofectamine-mediated transfection. STC cells respondto polyunsaturated fatty acids (PUFAs) in a similar fashion to tastereceptor cells (TRCs). However, unlike TRCs, PUFAs (10 µM) inhibitonly ~40-50% of the total DRK current in STC cells. Using patchclamp, we have examined the effect of linoleic acid (10 µM) on DRKcurrents in STC cells cotransfected with GFP and either KCNA5 orKCNC1. Overexpression of the fa-i KCNC1 channel leads to anincrease in total DRK current and a marked reduction in fatty acidresponsiveness consistent with our model. Currently, we are exploringwhether overexpression of the fa-s KCNA5 channel enhances the fattyacid induced inhibition of DRK currents. Our data support the idea thatfatty acid responsiveness in chemosensory cells is determined by therelative expression of fa-s and fa-i DRK channels and that this ratio mayhelp determine the magnitude of sensory signals conveyed by dietaryfat. Supported by DK59611 (TAG).55