Abstracts - Association for Chemoreception Sciences

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egulatory role in Fas-mediated cell death and is expressed in the olfactory epithelium during development. Using a transgenic strategy, which combines an early olfactory-specific promoter with the tetracycline-inducible system, we overexpressed FAF1 in immature OSNs, when their axons are actively seeking targets in the OB. Our data show that while overexpression of Faf1 does not induce cell death in immature OSNs, it does result in severe mis-targeting of axons to the OB. Interestingly, these phenotypes are reversible as OB organization returns to normal when Faf1 overexpression is shut down. Thus, we propose that Faf1 may play a functional role in axon guidance possibly through the modulation of apoptosis signaling. Acknowledgements: This study was supported by the NINDS/NIH intramural program. #43 SYMPOSIUM - WIRING THE OLFACTORY SYSTEMS Reduced Avoidance Response to Predator Odorants Associated with Wiring Defects in the Olfactory System of Robo-2 Mutant Mice Jean-François Cloutier 1,2 , Manon Lépine 1,2 , Tyler Cutforth 3 , Jin H. Cho 1,2 1 Montreal Neurological Institute Montreal, QC, Canada, 2 McGill University Montreal, QC, Canada, 3 UC Santa Cruz Santa Cruz, CA, USA The formation of complex stereotypic connections between olfactory sensory neurons (OSNs) and second order neurons in the olfactory bulb (OB) is believed to be important for accurate odorant information processing. Ablation of OSNs that innervate the dorsal (D) region of the OB leads to a loss of avoidance behavior in mice in response to aversive odorants such as trimethyl-thiazoline (TMT) and 2-methylbutyric (2MB) acid 1 . It remains to be determined whether more refined disruption of the glomerular map in these regions of the OB could have an effect on innate responses in mice. To examine this question, we have generated mice lacking expression of the axon guidance receptor Robo-2 specifically in OSNs and analyzed the targeting accuracy of axons projecting from two subsets of OSNs innervating the dorsal region of the OB. While MOR1-3-expressing axons that project to the DI region of the OB target accurately in robo-2 mutant mice, MOR174-9-expressing axons that innervate the DII region coalesce on glomeruli located more ventrally in robo-2 mutant mice. To examine the functional consequences of these wiring defects, we evaluated the avoidance behavior of wild type and mutant mice in response to TMT and 2MB acid. Robo-2 mutant mice showed a robust decrease in their avoidance behavior towards the predator odorant TMT but could be conditioned to avoid TMT using LiCl injections. Interestingly, robo-2 mutant mice showed similar avoidance behavior as wild-type mice in response to 2-MB acid. Taken together, our results indicate that defects in the wiring of the olfactory system can lead to selective loss of some innate behavioral responses in mice. 1. Kobayakawa et al. (2007) Nature 450:503-508. Acknowledgements: Canadian Institutes of Health Research #44 CLINICAL LUNCHEON - NEW CLINICAL TRIAL FUNDING OPPORTUNITIES AT NIDCD New clinical trial funding opportunities at NIDCD Gordon Hughes Program Officer, Clinical Trials, NIDCD The National Institute on Deafness and Other Communication Disorders is committed to building and expanding its clinical trials program to promote the development of interventions to treat or prevent disorders in hearing, balance, taste, smell, voice, speech and language. Three new clinical trial initiatives and funding opportunities, issued in July, 2008, can be found at http://www.nidcd.nih.gov/research/clinicaltrials. Individual application information can be found at http://www.nidcd.nih.gov/funding/foa/. The Phase I/II Preliminary Clinical Trial specifically targets studies that will provide preliminary data and optimize the design of the eventual phase III trial. The Phase III Clinical Trial Planning Grant is designed to permit early peer review of a proposed phase III clinical trial and is used to develop a detailed Manual of Procedures, train clinical sites and prepare case report forms. The Phase III Definitive Clinical Trial should have the potential to significantly impact on clinical practice or public health policy. NIDCD strongly encourages clinical trial applications in chemoreception sciences. #45 SYMPOSIUM - TRANSIENT DYNAMICS, METASTABLE STATES AND TEMPORAL CODING IN CHEMOSENSORY PROCESSING Frequency Transitions in Odor-Evoked Neural Oscillations Mark Stopfer 1 , Iori Ito 1 , Maxim Bazhenov 2 , Rose C-Y Ong 1,3 , Baranidharan Raman 1,4 1 NIH/NICHD Bethesda, MD, USA, 2 Department of Cell Biology and Neuroscience, University of California Riverside Riverside, CA, USA, 3 Department of Biochemistry, The Chinese University of Hong Kong Hong Kong, Hong Kong, 4 Chemical Senses and Technology Laboratory, NIST Gaithersburg, MD, USA Odor-evoked neural oscillations are ubiquitous in olfactory systems. How do these oscillations originate, and what determines their properties? In insects, odor-elicited oscillations are produced in the antennal lobe by interactions of excitatory projection neurons (PNs) and inhibitory local interneurons. In moths, we found that lengthy odor presentations elicited oscillations that were initially fast (~40 Hz) but then rapidly shifted to a slower rate (~10-20 Hz). Because this shift in frequency closely paralleled the intensity of output from the antenna, we first thought the oscillation rate was driven by the strength of the stimulus. However, we also found that changing the intensity (concentration) of the odor had almost no effect on the initial oscillation frequency. Individual olfactory receptor neurons (ORNs) showed a surprisingly narrow dynamic range owing to sensory adaptation and saturation. But because ORNs became less selective as the odor concentration increased, the size of the population of ORNs that responded to an odor increased with the concentration. Thus, in the periphery, the great majority of the olfactory system’s dynamic range derives from the size of the responsive population of ORNs, not the intensity of its response. Our recordings and a computational model showed that lengthy stimuli caused each ORN to adapt; this reduced the intensity of input to the oscillator circuit, reducing its output frequency. In 20 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)
contrast, changing the concentration of the odor changed the number of responsive ORNs, but not the intensity of the most responsive ORNs providing input to the oscillator circuit; thus the oscillation frequency remained stable. Acknowledgements: This work was supported by the Japan Society for the Promotion of Science (00169, 70510) to I.I., Joint NIH-NIST postdoctoral fellowship award by National Research Council to B.R., grants from NIH-NIDCD and NIH-NINDS to M.B. and an intramural grant from NIH-NICHD to M.S. #46 SYMPOSIUM - TRANSIENT DYNAMICS, METASTABLE STATES AND TEMPORAL CODING IN CHEMOSENSORY PROCESSING Multiple Roles for STDP in Shaping Olfactory Representations Stijn Cassenaer Caltech Pasadena, CA, USA Odor representations in insects undergo progressive transformations from the receptor array in the antenna, via the antennal lobe (AL), to the presumed site of odor learning, the mushroom body (MB). Broad activation of the AL by an olfactory stimulus gives rise to oscillatory population activity and diverging trajectories of projection neuron (PN) activation. Different points along these trajectories can be thought of as representing different aspects of the odor stimulus, and Kenyon cells (KCs), which decode PN activity in the MB, respond sparsely at specific time-points along the PN trajectories. Previous work suggests that individual oscillation cycles are meaningful units for the encoding and decoding of olfactory information by PNs and KCs. This appears to be the case also for extrinsic neurons in the mushroom body beta-lobe (bLNs), which decode the KCs‘ sparse responses. I will describe the results of intracellular recordings made from KCs and bLNs to examine synaptic transmission, plasticity and odor representation in this circuit. We have found that KC-bLN synapses undergo Hebbian spike-timing dependent plasticity (STDP) on a timescale similar to the oscillatory population discharge, which is generated by the AL and propagated throughout the circuit. This plasticity has a homeostatic effect on the phase of bLN firing, facilitates the synchronous flow of olfactory information, and maintains the segregation between oscillation cycles. We also address how the interaction of STDP with phase-locked inhibition and neuromodulation shapes the way odors are represented in the MB. Considered within the context of the circuit in which the KC-bLN network is embedded, these results suggest a mechanism for learning different aspects of an odor stimulus. Acknowledgements: Broad Fellows Program in Brain Circuitry. Multi University Research Initiative (ONR) #47 SYMPOSIUM - TRANSIENT DYNAMICS, METASTABLE STATES AND TEMPORAL CODING IN CHEMOSENSORY PROCESSING Timing in olfaction Dmitry Rinberg, Roman Shusterman, Matt Smear, Thomas Bozza sniff waveform, and the complex geometry of the nasal turbinates. Does the olfactory system preserve this precise timing information? And can an animal use this faster variation to guide behavior? To understand the temporal aspects of olfactory information processing, we combine electrophysiological, optogentic, and behavioral approaches. We have analyzed the temporal structure of mitral cell activity in awake mice. We found very precise spiking patterns relative to the sniffing cycle, with jitter as small as 20 ms during odor presentation. This precise timing may carry information about the stimulus during odor presentation: different odors evoke different patterns in the same cell and different cells respond differently to the same odors. To better control the timing of our stimulus, we have generated transgenic mice that express Channelrhodopsin2 in all olfactory sensory neurons (OSNs), which allows us to decouple sniffing from stimulus delivery by stimulating sensory neurons with light. We trained animals to discriminate different temporal patterns of stimulation. We found that mice can discriminate temporal difference as small as 10 ms relatively to the sniffing-breathing cycle. Precise temporal neuronal responses to odors and the ability of mice to discriminate spatially-identical OSN stimuli on the basis at sub-sniff-cycle timing differences provide strong evidence that precise stimulus timing plays as crucial a role in olfactory neuronal coding and perception as it does in other sensory modalities. Olfaction may not be such a ‘slow’ sense. #48 SYMPOSIUM - TRANSIENT DYNAMICS, METASTABLE STATES AND TEMPORAL CODING IN CHEMOSENSORY PROCESSING Meta-stable states in taste processing Donald B Katz Brandeis University Waltham, MA, USA Both mammalian gustatory cortical (GC) and amygdalar neurons respond to taste administration with time-varying progressions of firing rates, different “epochs” of which containing different types of information. When complex analyses are brought to bear on simultaneously-recorded GC ensembles, these temporal codes are revealed to be sequences of meta-stable population states; the progressions themselves are reliably taste-specific, but the timing of state-to-state transitions vary from trial to trial. In this talk, I show that such coherent sequences of meta-stable states are a common feature of decision-making networks under certain parameter settings, and that networks working in a “statesequence regime” have many advantages over other networks with regard to correct decision-making. I go on to present data demonstrating that the trial-to-trial variability of the observed sequences is an intrinsic part of attentive processing, quite possibly reflecting the recruitment of more distributed interregional neural networks to the task of taste identification. This leads me to preliminary quantification of amygdala-cortical statesequence coupling during attentive and inattentive taste responses. These data and analyses offer the beginning of a wholly new characterization of perceptual neural processing in the mammal. Acknowledgements: DC 006666, DC 007703, Swartz Foundation Olfaction is traditionally considered a ‘slow’ sense. However, recent evidence demonstrates that rodents are capable of making difficult odor discriminations rapidly, in as little as a single sniff. Can olfaction operate at even faster time scales? Odors can vary on a time scale finer than the period of a sniff cycle (roughly 100- 500 ms) - odors are temporally structured by air turbulence, the Abstracts are printed as submitted by the author(s) Abstracts | 21
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decreasing of endogenous volatiles
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pregnancy block. In order to unders
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familiarity and cultural difference
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perception of purine 5’-ribonucle
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(CT), the greater superficial petro
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were significantly different from o
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MSG on NaCl is evidently highlighte
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consisting of motors and IFT comple
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wing. Philip Callahan exposed insec
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seem to indicate that total nasal v
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possibly suggesting non-apoptotic m
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of 7/10, and causing eyes to water
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showed that N1/P2 latencies were lo
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differentiated patients with AD (M=
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pleasantness 3)of mixtures (A,B), A
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Index Aarts, H - P328 Abe, K - P88,
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Haase, L - P3, P4, P29, P355 Haddad
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Murata, Y - P272 Murphy, C - P3, P4
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Veldhuizen, M - P7, P24, P25, P242,
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Registration 7:30 am to 1:00 pm, 6:
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See you next year! AChemS 33rd Annu
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Abstracts - Association for Chemoreception Sciences

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