2009 Abstracts - Association for Chemoreception Sciences

data here from mouse studies using Cre/LoxP site-specificrecombination in which we genetically remove BDNF fromdiscrete populations of cells. To our knowledge, these studies arethe first to attempt to localize the source of BDNF controllingadult neurogenesis.#P237 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisIn vivo optical imaging of experience-induced olfactory bulbglomerular plasticityMax L. Fletcher 1 , Johannes Richter 2 , Wei R. Chen 11University of Texas Medical School Department of Neurobiologyand Anatomy Houston, TX, USA, 2 Yale University School ofMedicine New Haven, CT, USAWhile the olfactory system has been shown to have a remarkablecapability for undergoing experience-dependent plasticity, howsuch odor memories are imprinted in the adult olfactory neuronalcircuits remains unclear. This process most likely involves changesat multiple stages along the central olfactory processing pathways.One interesting site for plasticity is the olfactory glomerular layer.Within this layer, the organization of receptor neuron inputsallows odorant information to be transformed into an odorantspecificspatial map of glomerular activity. We have visualizedsuch activity patterns in vivo by using a recently-developedtransgenic mouse with a GFP-based calcium indicator(G-CaMP2) expressed in output neurons postsynaptic toolfactory nerve inputs. Unlike previously applied optical imagingmethods, this mouse allowed us to observed purely postsynapticodor maps in the glomerular layer. Using this mouse, we testedthe hypothesis that the olfactory learning process can significantlyalter olfactory bulb postsynaptic glomerular odorantrepresentations for the trained odorant. This was carried out bycomparing the odorant-evoked glomerular activity patterns in thesame animal before and after olfactory associative conditioningwith foot shock. Preliminary data suggests that conditioning witha given odorant significantly alters glomerular responses to thatodorant following training. These results suggest that simpleforms of olfactory experience can have a significant impact onolfactory odor coding even at the earliest stages of centralprocessing.#P238 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisMaternal Modulation of the Functional Emergence of theHippocampus in Context Fear Learning in Infant RatsCharlis Raineki 1,2,3 , Parker Holman 3 , Melissa Bugg 3 , AllysonBeasley 3 , Regina M. Sullivan 1,2,31Emotional Brain Institute, Nathan S. Kline Institute forPsychiatric Research Orangeburg, NY, USA, 2 Child andAdolescent Psychiatry, NYU Langone Medical Center New York,NY, USA, 3 Department of Zoology, University of OklahomaNorman, OK, USAlearning ontogenetically emerges at weaning. First, we assesswhether the hippocampus is responsible for pups’ newly emergingcontext learning. In all experiments, postnatal day (PN) 21 andPN24 rat pups received 10 pairings of odor-0.5mA shock orcontrol unpaired odor-shock or odor only. Some pups were usedfor context, cue or odor avoidance tests, while the remaining pupswere used for c-Fos immunohistochemistry to assess hippocampalactivity during acquisition. Our results show that cue and odoravoidance learning were similar at both ages, while contextual fearlearning and learning associated hippocampal (CA1, CA3 anddentate gyrus) activity only occurred in PN24 paired pups.To assess a causal relationship between the hippocampus andcontext conditioning, we infused muscimol into the hippocampus,which blocked acquisition of context fear learning in PN24 pups,but did not affect cue learning or aversion to the odor at PN21 orPN24. Secondly, we assess whether the emergence of the contextfear learning is modulated by the maternal presence. PN24 ratpups were odor-shock conditioned with or without maternalpresence. Similarly to muscimol infusion into the hippocampusresult, maternal presence prevents context fear learning at PN24but do not affect cue learning and odor aversion. The resultssuggest that maternal presence modulates the newly emergingcontextual fear learning exhibited by PN24 pups that is supportedby the hippocampus.#P239 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisRethinking statistical analysis of associative learning in anolfactometerNicolas Busquet, Diego RestrepoUniversity of Colorado Denver Denver, CO, USAStatistical analyses of performance in olfactory learning taskstypically focus on confirming that the association has beenlearned rather than investigating the process through which it isestablished. In the former approach, the animal needs to beproficient in the task before a particular association can bedemonstrated. Because the animal may make the association andthus treat the stimuli differently before reaching the performancestandard, the statistical analysis of the acquisition process shouldnot be constrained by a set criterion. Here I present a new methodto calculate when the subject’s behavior departs from randomness.This is done by comparing the probability value associated withthe animal’s performance with a spectrum of probability valuesgenerated from multiple simulations of random behavior in thesame task. These probability values are incremented on a singleeventbasis to detect more precise timing of the learning process.This new approach is also more flexible in handling variabilitywithin and across individuals and sessions. The efficacy of thismethod is evident in the reported results from a pilot study usingnatural and artificial odors. Applying our method providesevidence that mice can achieve better than chance performanceconsiderably sooner than previously demonstrated with thestandard statistical analysis.P O S T E R SThe hippocampus is important for the formation of associativememories, such as acquiring information about context (i.e. theplace where an experience occurred) during emotional learning(i.e. fear conditioning). Previous work suggests that contextAbstracts | 101