Analysis of Training-Induced Changes in Ethyl Acetate Odor Maps Using a New Computational Tool to Map the Glomerular Layer of the Olfactory Bulb

Salcedo, Ernesto E.; Zhang, Chunbo; Kronberg, Eugene; Restrepo, Diego

doi:10.1093/chemse/bji055

Cited by 56 publications

(64 citation statements)

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“…Odor-induced MOB glomerular activation was mapped using Matlab software in conjunction with the GLOM-MAP program [11]. The location of each activated glomerulus was mapped according to radial angle from a central point of origin and rostral-caudal distance through the bulb.…”

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Comparison of urinary odor-induced glomerular activation in the main olfactory bulb of aromatase knock-out and wild type female mice

Martel

Keller

Douhard

et al. 2007

Neuroscience Letters

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Previously [D.W. Wesson, M. Keller, Q. Douhard, M.J. Baum, J. Bakker, Enhanced urinary odor discrimination in female aromatase knockout mice, Horm. Behav. 49 (2006) [580][581][582][583][584][585][586] female aromatase knock out mice successfully learned to discriminate in a food-motivated go/no-go task between urinary volatiles from ovariectomized female mice treated with estradiol as opposed to estradiol plus progesterone whereas wild type females failed to learn this odor discrimination. We asked whether this behavioral difference is reflected in the ability of these two types of urinary volatiles to differentially stimulate Fos expression in juxtaglomerular cells (an index of glomerular activation) of the main olfactory bulb (MOB) in wild type versus ArKO female mice. Statistically significant differences in the profiles of MOB glomerular activation were seen in ovariectomized, estrogen-treated ArKO as well as WT female subjects following exposure to urinary volatiles from ovariectomized females given estradiol alone as opposed to estradiol plus progesterone. Therefore, previously observed differences between females of the two genotypes in their behavioral responses to these odors must reflect differential processing in more central segments of the olfactory pathway instead of in the MOB. © 2007 Elsevier Ireland Ltd. All rights reserved.Keywords: Estradiol; Progesterone; Pheromone; Sexual differentiation; Fos expression Olfactory receptor neurons in the main olfactory epithelium (MOE) that express the same olfactory receptor gene extend axons that target the same 1-2 glomeruli in the ipsilateral main olfactory bulb (MOB) [10]. Recently [6] a class of 'trace amineassociated receptors' was identified in the MOE which respond to volatile amines emitted from mouse urine. A series of studies by Restrepo and co-workers [13,12,7] showed that volatile urinary odors from male mice augmented Fos expression in juxtaglomerular cells of the MOB (an index of glomerular activation) of female conspecifics. More recently, Martel and Baum [9] used this same method to show that urinary volatiles from male versus estrous female mice activated overlapping, but distinguishable clusters of glomeruli located in the ventral portion of the MOB in both sexes. In another study [8] volatile constituents of mouse urine were shown to stimulate activity in MOB mitral cells. Wesson et al. [14] recently assessed the possible contribution of perinatal exposure to estradiol on the later ability of female mice to discriminate volatile urinary odors from * Corresponding author. conspecifics of different sexes and endocrine status. Detection of these social odorants plays a significant role in sexual, aggressive, and maternal behaviors in mice, therefore the possible role of perinatal estradiol exposure on the later ability of female mice to discriminate between urinary odors of conspecifics is of particular interest. Female mice with a null mutation of the Cyp-19 gene (ArKO mice), which encodes the estradiol synthesizing enzyme, aroma...

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confidence: 99%

Comparison of urinary odor-induced glomerular activation in the main olfactory bulb of aromatase knock-out and wild type female mice

Martel

Keller

Douhard

et al. 2007

Neuroscience Letters

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“…Thus, the activity of surrounding juxtaglomerular cells reflects activation of a particular glomerulus. To study whether disruption of gap junctions in the olfactory epithelium affects odor presentation in the olfactory bulb, I constructed odor activity maps of octaldehyde in OlfDNCX and WT using a mapping tool developed in Restrepo laboratory [48,49]. The odor activation maps were generated by scoring odor-activated glomeruli throughout the entire glomerular layer of the olfactory bulb and then performing a series of computational analyses.…”

Section: Resultsmentioning

confidence: 99%

“…Determination of an activated glomerulus was made by measurement of odor-evoked c-fos mRNA transcription in juxtaglomerular cells surrounding the glomerulus. More details of the odor activity mapping is described in the "Methods" section and in previous publications [48,49]…”

Section: Resultsmentioning

confidence: 99%

“…In OlfDNCX, a total number of 458 ± 25.5 glomeruli were activated, while the number of glomeruli activated by octaldehyde in WT was 620 ± 59.5 (mean ± SE, n = 8 for each group, p < 0.05). In order to explore regional differences in glomerular activation, I used a point by point Mann-Whitney test with confidence interval p values corrected for multiple comparisons using the false discovery rate procedure [45,48,49]. The areas within the black contour lines of Figure 5C were statistically different.…”

Section: Resultsmentioning

confidence: 99%

“…A point to point Mann-Whitney test was performed as in Schaefer et al [49] to compare the difference of odor maps. A detail description of an upgraded odor mapping program is described elsewhere [48]. …”

Section: Methodsmentioning

confidence: 99%

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Gap junctions in olfactory neurons modulate olfactory sensitivity

Zhang

2010

BMC Neurosci

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BackgroundOne of the fundamental questions in olfaction is whether olfactory receptor neurons (ORNs) behave as independent entities within the olfactory epithelium. On the basis that mature ORNs express multiple connexins, I postulated that gap junctional communication modulates olfactory responses in the periphery and that disruption of gap junctions in ORNs reduces olfactory sensitivity. The data collected from characterizing connexin 43 (Cx43) dominant negative transgenic mice OlfDNCX, and from calcium imaging of wild type mice (WT) support my hypothesis.ResultsI generated OlfDNCX mice that express a dominant negative Cx43 protein, Cx43/β-gal, in mature ORNs to inactivate gap junctions and hemichannels composed of Cx43 or other structurally related connexins. Characterization of OlfDNCX revealed that Cx43/β-gal was exclusively expressed in areas where mature ORNs resided. Real time quantitative PCR indicated that cellular machineries of OlfDNCX were normal in comparison to WT. Electroolfactogram recordings showed decreased olfactory responses to octaldehyde, heptaldehyde and acetyl acetate in OlfDNCX compared to WT. Octaldehyde-elicited glomerular activity in the olfactory bulb, measured according to odor-elicited c-fos mRNA upregulation in juxtaglomerular cells, was confined to smaller areas of the glomerular layer in OlfDNCX compared to WT. In WT mice, octaldehyde sensitive neurons exhibited reduced response magnitudes after application of gap junction uncoupling reagents and the effects were specific to subsets of neurons.ConclusionsMy study has demonstrated that altered assembly of Cx43 or structurally related connexins in ORNs modulates olfactory responses and changes olfactory activation maps in the olfactory bulb. Furthermore, pharmacologically uncoupling of gap junctions reduces olfactory activity in subsets of ORNs. These data suggest that gap junctional communication or hemichannel activity plays a critical role in maintaining olfactory sensitivity and odor perception.

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Olfaction: Central Processing

McGann¹

2013

Encyclopedia of Life Sciences

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Olfactory receptor neurons in the nasal epithelium detect a huge variety of airborne chemicals (termed ‘odourants’) and encode information about these stimuli in the form of action potentials. This code is then transmitted to the brain, where spatiotemporal patterns of neural activity represent the identity, concentration and temporal dynamics of the odourants. Neural processing of olfactory information at multiple levels in the brain mediates odour recognition, synthetic olfactory perceptions and provides feedback control to the initial stages of the olfactory pathway. This article presents some of the challenges in olfactory information processing and then reviews our current knowledge of the mechanisms by which the olfactory bulb and olfactory cortex represent odours and analyse olfactory information. Key Concepts: The chemical identity of an odourant is represented by the set of ORNs it stimulates and determines the odour's perceived quality. The concentration of an odourant is represented jointly by the amplitude of the ORN response and the recruitment of ORNs expressing lower affinity receptors; this determines the odour's perceived intensity. Each olfactory bulb glomerulus receives axonal projections from a set of ORNs expressing the same odour receptor. An odour stimulates a subset of ORNs (based on their odour receptor expression) and thus drives activity in a corresponding subset of olfactory bulb glomeruli – this odour‐to‐glomerulus mapping is one of the most accessible codes in the nervous system. Activity in olfactory bulb glomeruli is determined by a complex set of interactions among ORN sensory inputs, interneurons within and between glomeruli and modulatory inputs from other brain regions. The set of mitral cells responding during odour presentation represents the chemical identity of the odour, whereas their firing frequency and timing provides additional information about the odour concentration. Activity in mitral cells is shaped by complex interactions with inhibitory granule cells that interconnect mitral cells receiving disparate sensory input. Neurons in piriform cortex respond to specific combinations of input from mitral cells in the olfactory bulb, thus selectively responding to certain odours or combinations of odours.

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Analysis of Training-Induced Changes in Ethyl Acetate Odor Maps Using a New Computational Tool to Map the Glomerular Layer of the Olfactory Bulb

Cited by 56 publications

References 42 publications

Comparison of urinary odor-induced glomerular activation in the main olfactory bulb of aromatase knock-out and wild type female mice

Comparison of urinary odor-induced glomerular activation in the main olfactory bulb of aromatase knock-out and wild type female mice

Gap junctions in olfactory neurons modulate olfactory sensitivity

Olfaction: Central Processing

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