Functional units in the olfactory system

Leon, Michael; Johnson, Brett A.

doi:10.1073/pnas.0607416103

Cited by 7 publications

(4 citation statements)

References 18 publications

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“…Examples include the remarkable ability of rodents to identify individuals and hymenopterans to identify nestmates through “signature mixtures” of common VOCs released in characteristic proportions (see Wyatt 2010 for review). The well-established combinatorial coding hypothesis (Xu et al 2000; Leon and Johnson 2006; Koulakov et al 2007; Galizia and Szyszka 2008) may explain how qualitatively different olfactory stimuli are represented in the olfactory bulb or AL, but perhaps not the quantitative relationships critical to the salience or behavioral significance of a particular mixture, as the same set of glomeruli can be activated by similar mixtures that have very different behavioral significance (c.f. Brandstaetter et al 2011).…”

Section: Discussionmentioning

confidence: 99%

Synchronous firing of antennal-lobe projection neurons encodes the behaviorally effective ratio of sex-pheromone components in male Manduca sexta

et al. 2013

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Olfactory stimuli that are essential to an animal's survival and reproduction are often complex mixtures of volatile organic compounds in characteristic proportions. Here, we investigated how these proportions are encoded in the primary olfactory processing center, the antennal lobe (AL), of male Manduca sexta moths. Two key components of the female's sex pheromone, present in an approximately 2:1 ratio, are processed in each of two neighboring glomeruli in the macroglomerular complex (MGC) of males of this species. In wind-tunnel flight experiments, males exhibited behavioral selectivity for ratios approximating the ratio released by conspecific females. The ratio between components was poorly represented, however, in the firing-rate output of uniglomerular MGC projection neurons (PNs). PN firing rate was mostly insensitive to the ratio between components, and individual PNs did not exhibit a preference for a particular ratio. Recording simultaneously from pairs of PNs in the same glomerulus, we found that the natural ratio between components elicited the most synchronous spikes, and altering the proportion of either component decreased the proportion of synchronous spikes. The degree of synchronous firing between PNs in the same glomerulus thus selectively encodes the natural ratio that most effectively evokes the natural behavioral response to pheromone.

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Section: Discussionmentioning

confidence: 99%

Synchronous firing of antennal-lobe projection neurons encodes the behaviorally effective ratio of sex-pheromone components in male Manduca sexta

et al. 2013

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“…Volatile odors generally activate multiple receptors in the olfactory epithelium [14][15][16][17] . Odor identity is encoded by the combinatorial activation of glomeruli, mitral/tufted cells in the olfactory bulb and by distributed sets of neurons in the cortices [17][18][19][20][21][22][23][24] . Lateral excitation and inhibition mediated by interconnected neuronal networks may transform receptor activation into more complex population activities.…”

Section: Linear Decoding Of Odors From Glomeruli Responsesmentioning

confidence: 99%

Encoding Innately Recognized Odors via a Generalized Population Code

Qiu

et al. 2020

Preprint

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Odors carrying intrinsic values often trigger instinctive aversive or attractive responses.Innate valence is thought to be conveyed through hardwired circuits along the olfactory pathway, insulated from influences of other odors. Here we show that in mice, mixing of innately aversive or attractive odors with a neutral odor abolishes the behavioral responses. Surprisingly, mixing of two odors with the same valence also abolishes the expected responses. Recordings from the olfactory bulb indicate that odors are not masked at the level of peripheral activation and glomeruli independently encode components in the mixture. However, crosstalk among the mitral/tufted cells changes their patterns of activity such that those elicited by the congruent mixtures can no longer be decoded as separate components. The changes in behavioral and mitral/tufted cell responses are associated with reduced activation of brain areas linked to odor preferences. Thus, interactions of odor channels at the earliest processing stage in the olfactory pathway lead to re-coding of odor identity. These results are inconsistent with insulated labeled lines and support a model of a common mechanism of odor recognition for both innate and learned valence associations.

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“…OSNs project their axons via the olfactory nerve to the olfactory bulb, where they segregate by receptor type such that the axons of all the OSNs expressing a given receptor type converge into one or two specific glomeruli (Figure 1B; Mombaerts 2006). The positions of these glomeruli are relatively stereotyped (Soucy et al 2009) and organized according to a broad chemotopy (Leon and Johnson 2006). The pattern of OSN input to olfactory bulb glomeruli thus represents the chemical identity of the odorant (Sharp et al 1975) and maps onto the perception of odorant quality (Youngentob et al 2006;Linster et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Presynaptic Inhibition of Olfactory Sensory Neurons: New Mechanisms and Potential Functions

McGann

2013

Chemical Senses

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Presynaptic inhibition is the suppression of neurotransmitter release from a neuron by inhibitory input onto its presynaptic terminal. In the olfactory system, the primary sensory afferents from the olfactory neuroepithelium to the brain's olfactory bulb are strongly modulated by a presynaptic inhibition that has been studied extensively in brain slices and in vivo. In rodents, this inhibition is mediated by γ-amino butyric acid (GABA) and dopamine released from bulbar interneurons. The specialized GABAergic circuit is now well understood to include a specific subset of GAD65-expressing periglomerular interneurons that stimulate presynaptic GABAB receptors to reduce presynaptic calcium conductance. This inhibition is organized to permit the selective modulation of neurotransmitter release from specific populations of olfactory sensory neurons based on their odorant receptor expression, includes specialized microcircuits to create a tonically active inhibition and a separate feedback inhibition evoked by sensory input, and can be modulated by centrifugal projections from other brain regions. Olfactory nerve output can also be modulated by dopaminergic circuitry, but this literature is more difficult to interpret. Presynaptic inhibition of olfactory afferents may extend their dynamic range but could also create state-dependent or odorant-specific sensory filters on primary sensory representations. New directions exploring this circuit's role in olfactory processing are discussed.

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Functional units in the olfactory system

Cited by 7 publications

References 18 publications

Synchronous firing of antennal-lobe projection neurons encodes the behaviorally effective ratio of sex-pheromone components in male Manduca sexta

Synchronous firing of antennal-lobe projection neurons encodes the behaviorally effective ratio of sex-pheromone components in male Manduca sexta

Encoding Innately Recognized Odors via a Generalized Population Code

Presynaptic Inhibition of Olfactory Sensory Neurons: New Mechanisms and Potential Functions

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