1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

405 Poster Central Taste and Chemosensory BehaviorDIFFERENTIAL INTERACTIONS BETWEEN AMYGDALA,INSULA, CAUDOMEDIAL AND CAUDOLATERALORBITOFRONTAL CORTEX DEPEND UPON THE NATUREOF STIMULUS PERCEIVED OR TASK PERFORMEDBender G. 1 , Gitelman D.R. 2 , Small D.M. 3 1 InterdepartmentalNeuroscience, Yale University and J.B. Pierce Laboratory, New Haven,CT; 2 Neurology, Northwestern University, Chicago, IL; 3 Psychology,Yale University, New Haven, CTPreviously we used fMRI and identified a region of anteriorinsula/frontal operculum (AIFO) that responded during perception of ataste but not a tasteless solution, irrespective of the nature of the task(detecting its presence, judging its pleasantness or its quality, orpassively tasting). In contrast, a region of caudolateral orbitofrontalcortex (OFC) responded preferentially when Ss judged pleasantness,irrespective of whether they received a taste or a tasteless solution. Herewe used effective connectivity analyses (ECA) to assess potentialdifferential connectivity between regions depending on the nature of thestimulus or the task. ECA showed greater connectivity between theAIFO and bilateral amygdala when the Ss tasted passively compared towhen they evaluated a taste, suggesting that even though BOLDresponse in the AIFO is not affected by task, information transferbetween it and the amygdala differs depending on whether anevaluation is made or not. We also found greater connectivity betweencaudolateral and caudomedial OFC when Ss received a taste versus atasteless solution, indicating that connectivity between these OFC tasteregions is dependent on sensory stimulation. This finding is inaccordance with work by Pritchard et al. (2005) highlighting theimportance of the caudomedial OFC in gustatory processing. (supportedby NIH/IDCD R03 DC006169)407 Poster Central Taste and Chemosensory BehaviorTASTE GUIDED BEHAVIOR IN DROSOPHILAMELANOGASTER TO TRADITIONAL PSYCHOPHYSICALTEST SOLUTIONSGordesky-Gold B. 1 , Rivers N. 1 , Ahmed O. 1 , Breslin P. 1 1 MonellChemical Senses Center, Philadelphia, PAThe ability to perceive the taste quality of a food source is critical forthe survival of an organism. Flies are omnivores and have very similartaste sensitivities as humans with regard to attractants and repellents.Like humans, they are attracted to and ingest many sugars and dilutesalts and avoid ingesting toxins and acids. We have tested flies from thewildtype laboratory strain Canton-S (CS) for their taste responses to avariety of compounds considered sweet or bitter by humans. Many ofthese compounds have never before been tested in Drosophila. Fliesresponded to and rejected many stimuli that humans find bitter. Fliesreject quinine, caffeine, denatonium, and MgSO 4 . On the other hand,flies appear insensitive to PROP, PTC, SOA, limonin, cyclo-LeuTrp,epicatichin, and naringin at the concentrations tested. When testingartificial sweeteners flies have, so far, found all tested compounds to beappetitive. The intensive sweeteners tested thus far included sodiumcyclamate, sodium saccharin, sucralose, aspartame, neohesperidindihydrochalcone (NHDC), glycyrrhizic acid, and thaumatin. Some ofthese sweeteners do not elicit a positive sweet response from rodents;sodium cyclamate, aspartame, NHDC and thaumatin taste sweet only tohumans and old world monkeys. New world monkeys and rodents donot respond to these sweeteners. We conclude that Drosophila tasteresponses are often more similar to human responses than are rodentsand those of many primates. The strength of Drosophila as a behavioralgenetic model make these data especially useful for taste gene discoverypurposes.406 Poster Central Taste and Chemosensory BehaviorCHANGE OF SERUM AND LEPTIN RECEPTORIMMUNOREACTIVITY IN THE AMYGDALA OF RATSFOLLOWING INTRAORAL INFUSION OF SWEET TASTANTYan J. 1 , Han Z. 1 , Jiang E. 1 1 Physiology and Pathaphysiology, Xi'anJiaotong University Medical Center, Xi'an, Shaanxi, ChinaTo determine whether the level of the leptin and the leptin receptor(OB-R) expression in amygdala changes following sweet taste stimuli,the serum leptin concentration was measured by using rat leptin RIAkit, long form of leptin receptor (OB-Rb) mRNA in the brain sectionswas examined by in situ hybridisation (ISH) and the expression of OB-R was assessed by immunohistochemistry ABC method with a highlyspecific goat anti-OB-R antibody. Comparing with the control group(intraoral infusion of distilled water), the level of serum leptin increasedin the sweet group (sucrose and saccharin) (p < 0.05). Many neuronalbodies and dendritic processes in amygdala, which have intensiverelationship with taste and feeding, showed leptin receptorimmunoreativity (LR-IR). But the count of positive-stained cells inamygdala showed no significant difference between the tastestimulation group and the control group. The level of OB-Rb mRNAexpression increased in the basolateral part of the amygdala (BLA),while no different expression was found in the central nucleus ofamygdala (CeA) after sweet tastant intraoral infusion. These findingslead us to study possible effects of leptin on taste responses. Probably,leptin influences food intake by means of the sense of taste. supportedby China NSF grants iNo.30270454 and 30300111 j.408 Poster Central Taste and Chemosensory BehaviorDOES LEARNING SHAPE OLFACTORY ACUITY IN THEMOTH MANDUCA SEXTA?Sprouse R.A. 1 , Cassis J.J. 1 , Daly K.C. 1 1 Biology, West VirginiaUniversity, Morgantown, WVLearning changes the neural processing of odor in primary olfactorycenters. These changes are manifest as evolving spatial and temporalrepresentations. The functional role of these changes, however, remainsa mystery. One model predicts that olfactory acuity is learningdependentand sharpens with experience. To test this prediction, we firstconditioned M. sexta moths to respond to 1-octanol using a Pavlovianolfactory-learning paradigm. Moths were placed into one of 4 groupsreceiving 1, 2, 4 or 8 conditioning trials. Twenty four hours aftertraining, moths were tested with a homologous series of alcohols in apseudo-randomized sequence. Results indicated that there was asharpening of the generalization slope only between groups receivingone verses two conditioning trials. However, as the number ofconditioning trials increased, only a general increase in responsivenesswas observed, suggesting higher acquisition and not acuity per se. Tofurther explore this result we performed two more experiments. First,we replicated the above methods but tested with molecularly distinctodorants to assess whether changing gradients are related to taskdifficulty. In a final experiment, moths received 2 blocks of 8conditioning trials, each block separated by 24 h. Following each blockand again 24 h after the last block, moths were tested with thehomologous series of alcohols. This procedure assessed whether acuitymight be short-term and whether additional conditioning trials enhancesacuity. Results of these experiments will be discussed. This work wassupported by NIH-NIDCD DC05535 to KCD & NIH-NCRR RR015574to GS & KCD.102