Odor Concentration Change Coding in the Olfactory Bulb

Parabucki, Ana; Bizer, Alexander; Morris, Genela; Munoz, Antonio E.; Bala, Avinash D. S.; Smear, Matthew C.; Shusterman, Roman

doi:10.1523/eneuro.0396-18.2019

Cited by 37 publications

(38 citation statements)

References 59 publications

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“…Another dimension of smell encoding, besides keeping track of odorant concentrations, is for neurons to also represent concentration differences of a given odor (Parabucki et al, 2019). Despite facing a dynamic environment where they encounter hundreds to thousands of volatile odors at various concentration gradients, humans and animals are capable of maintaining stable odor quality perception across concentrations (Krone et al, 2001;Wachowiak and Cohen, 2001;Uchida and Mainen, 2007;Mainland et al, 2014;Sirotin et al, 2015;Wilson et al, 2017).…”

Section: Specific Ors Encoding Odor Identitymentioning

confidence: 99%

Concentration-Dependent Recruitment of Mammalian Odorant Receptors

Ikegami

Vihani

et al. 2020

eNeuro

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A fundamental challenge in studying principles of organization used by the olfactory system to encode odor concentration information has been identifying comprehensive sets of activated odorant receptors (ORs) across a broad concentration range inside freely behaving animals. In mammals, this has recently become feasible with high-throughput sequencing-based methods that identify populations of activated ORs in vivo. In this study, we characterized the mouse OR repertoires activated by the two odorants, acetophenone and 2,5-dihydro-2,4,5trimethylthiazoline, from 0.01% to 100% (v/v) as starting concentrations using phosphorylated ribosomal protein S6 capture followed by RNA-Seq. We found Olfr923 to be one of the most sensitive ORs that is enriched by acetophenone. Using a mouse line that genetically labels Olfr923-positive axons, we provided evidence that acetophenone activates the Olfr923 glomeruli in the olfactory bulb. Through molecular dynamics stimulations, we identified amino acid residues in the Olfr923 binding cavity that facilitate acetophenone binding. This study sheds light on the active process by which unique OR repertoires may collectively facilitate the discrimination of odorant concentrations. 4 Significance Statement The ability of animals to discriminate odors over a range of odor concentrations while recognizing concentration-invariant odor identity presents an encoding challenge for the olfactory system. To further our understanding on how animals sense odors at different concentrations, it is important to describe how odor concentration information is represented at the receptor level. Here, we establish a sensitive in vivo approach to screen populations of odorant receptors enriched in the odor-activated sensory neurons in mice. We identified comprehensive lists of enriched odorant receptors against a 10,000-fold concentration range for two odorants. Describing the concentration-dependent activation for unique populations of odorant receptors is fundamental for future studies in determining how individual odorant receptors contribute to olfactory sensitivity and odor intensity coding.

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Section: Specific Ors Encoding Odor Identitymentioning

confidence: 99%

Concentration-Dependent Recruitment of Mammalian Odorant Receptors

Ikegami

Vihani

et al. 2020

eNeuro

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“…stereo comparison is not necessary in this task ( Fig. 2F; = 13), and that temporal comparisons across sniffs (Catania 2013; Parabucki et al 2019) play a larger role under our task conditions.…”

Section: Mice Can Use Gradient Cues In Turbulent Flowmentioning

confidence: 84%

Sniff-synchronized, gradient-guided olfactory search by freely moving mice

Findley

Wyrick

Cramer

et al. 2020

Preprint

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For many organisms, searching for relevant targets such as food or mates entails active, strategic sampling of the environment. Finding odorous targets may be the most ancient search problem that motile organisms evolved to solve. While chemosensory navigation has been well characterized in micro-organisms and invertebrates, spatial olfaction in vertebrates is poorly understood. We have established an olfactory search assay in which freely-moving mice navigate noisy concentration gradients of airborne odor. Mice solve this task using concentration gradient cues and do not require stereo olfaction for performance. During task performance, respiration and nose movement are synchronized with tens of milliseconds precision. This synchrony is present during trials and largely absent during inter-trial intervals, suggesting that sniff-synchronized nose movement is a strategic behavioral state rather than simply a constant accompaniment to fast breathing. To investigate the spatiotemporal structure of these active sensing movements, we used machine learning methods to parse motion trajectories into elementary movement motifs. Motifs fall into two clusters, which correspond to investigation and approach states. Investigation motifs lock precisely to sniffing, such that the individual motifs preferentially occur at specific phases of the sniff cycle. This work clarifies sensorimotor strategies for mouse olfactory search and guides ongoing work into the underlying neural mechanisms. Bhattacharyya U, Singh Bhalla U. Robust and rapid air borne odor tracking without casting. eNeuro. 2015 11; 2(6):Eneuro.0102-15. doi: 10.1523/ENEURO.0102-15.2015. Bi S, Sourjik V. Stimulus sensing and signal processing in bacterial chemotaxis.

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“…Indeed, the transformation by the brain of the signal originating from the nose is not completely understood. The glomeruli are described as a temporally well-organized unit playing an important role in signal transformation that can be compared to the thalamus’ role in other sensory pathways; for example, helping to discriminate odor concentration changes for odor source localization [53,54,55,56]. Another problem emerges once the signal has been treated by the brain; that is, expressing the perceived odor in a way that everyone can understand.…”

Section: Olfaction Mechanismsmentioning

confidence: 99%

Is It Possible to Predict the Odor of a Molecule on the Basis of its Structure?

Genva

Kemene

Deleu

et al. 2019

IJMS

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The olfactory sense is the dominant sensory perception for many animals. When Richard Axel and Linda B. Buck received the Nobel Prize in 2004 for discovering the G protein-coupled receptors’ role in olfactory cells, they highlighted the importance of olfaction to the scientific community. Several theories have tried to explain how cells are able to distinguish such a wide variety of odorant molecules in a complex context in which enantiomers can result in completely different perceptions and structurally different molecules. Moreover, sex, age, cultural origin, and individual differences contribute to odor perception variations that complicate the picture. In this article, recent advances in olfaction theory are presented, and future trends in human olfaction such as structure-based odor prediction and artificial sniffing are discussed at the frontiers of chemistry, physiology, neurobiology, and machine learning.

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Odor Concentration Change Coding in the Olfactory Bulb

Cited by 37 publications

References 59 publications

Concentration-Dependent Recruitment of Mammalian Odorant Receptors

Concentration-Dependent Recruitment of Mammalian Odorant Receptors

Sniff-synchronized, gradient-guided olfactory search by freely moving mice

Is It Possible to Predict the Odor of a Molecule on the Basis of its Structure?

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