Representations of Odor in the Piriform Cortex

Stettler, Dan D.; Axel, Richard

doi:10.1016/j.neuron.2009.09.005

Cited by 538 publications

(530 citation statements)

References 51 publications

(76 reference statements)

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“…Recent anatomical studies in mice showed that axons from identified glomeruli project diffusely throughout the piriform cortex [6][7][8][9] , the largest target area of the OB, and that piriform neurons receive convergent inputs from multiple mitral cells distributed throughout the OB 10 . These findings are consistent with an optical imaging study that found no apparent spatial organization of odour-evoked activity patterns in the piriform cortex 11 . In contrast, the anterior olfactory nucleus and the cortical amygdala receive topographic and biased projections from the OB, respectively 9,10 .…”

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confidence: 91%

Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling

et al. 2014

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Chemotopic odour representations in the olfactory bulb are transferred to multiple forebrain areas and translated into appropriate output responses. However, a comprehensive projection map of bulbar output neurons at single-axon resolution is lacking in vertebrates. Here we unravel a projectome of the zebrafish olfactory bulb through genetic single-neuron tracing and image registration. We show that five major target regions receive distinct modes of projections from olfactory bulb glomeruli. The central portion of posterior telencephalon receives non-selective, interspersed inputs from all glomeruli, whereas the ventral telencephalon is diffusely innervated by axons from particular glomerular clusters. The right habenula and posterior tuberculum (diencephalic nuclei) receive convergent inputs from restricted and all glomerular clusters, respectively. The bulbar recurrent projections are coarsely topographic. Thus, the primary chemotopic organization is transformed into distinct sensory representations in higher olfactory centres. These findings provide a framework to understand general principles as well as species-specific features in decoding of odour information.

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confidence: 91%

Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling

et al. 2014

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“…For example, humans are very poor at identifying components in a mixture, even when they are familiar with the components alone (5-7). Similarly, cortical patterns of neural activity induced by a mixture are unique, not a combination of neural activities induced by the mixtures' components (25)(26)(27)(28)(29). Moreover, the pattern of neural activity in the olfactory bulb induced by the smell of a natural object typically reflects the pattern associated with the dominant monomolecular odorant (alone) associated with that object (30).…”

Section: Discussionmentioning

confidence: 99%

Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white

Weiss

Snitz

Yablonka

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

131

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In vision, two mixtures, each containing an independent set of many different wavelengths, may produce a common color percept termed "white." In audition, two mixtures, each containing an independent set of many different frequencies, may produce a common perceptual hum termed "white noise." Visual and auditory whites emerge upon two conditions: when the mixture components span stimulus space, and when they are of equal intensity. We hypothesized that if we apply these same conditions to odorant mixtures, "whiteness" may emerge in olfaction as well. We selected 86 molecules that span olfactory stimulus space and individually diluted them to a point of about equal intensity. We then prepared various odorant mixtures, each containing various numbers of molecular components, and asked human participants to rate the perceptual similarity of such mixture pairs. We found that as we increased the number of nonoverlapping, equal-intensity components in odorant mixtures, the mixtures became more similar to each other, despite not having a single component in common. With ∼30 components, most mixtures smelled alike. After participants were acquainted with a novel, arbitrarily named mixture of ∼30 equal-intensity components, they later applied this name more readily to other novel mixtures of ∼30 equal-intensity components spanning stimulus space, but not to mixtures containing fewer components or to mixtures that did not span stimulus space. We conclude that a common olfactory percept, "olfactory white," is associated with mixtures of ∼30 or more equal-intensity components that span stimulus space, implying that olfactory representations are of features of molecules rather than of molecular identity.odor | sensory perception | smell

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“…Recent data suggest that a similar organizational logic may be operative in mammals, where information from the olfactory bulb bifurcates to project to limbic structures and the piriform cortex. Stereotyped connections to the amygdala may mediate innate olfactory responses and random inputs to the piriform cortex (38) may mediate more measured or learned olfactory behavior.…”

Section: Discussionmentioning

confidence: 99%

Generating sparse and selective third-order responses in the olfactory system of the fly

Luo¹,

Axel

Abbott

2010

Proc. Natl. Acad. Sci. U.S.A.

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In the antennal lobe of Drosophila, information about odors is transferred from olfactory receptor neurons (ORNs) to projection neurons (PNs), which then send axons to neurons in the lateral horn of the protocerebrum (LHNs) and to Kenyon cells (KCs) in the mushroom body. The transformation from ORN to PN responses can be described by a normalization model similar to what has been used in modeling visually responsive neurons. We study the implications of this transformation for the generation of LHN and KC responses under the hypothesis that LHN responses are highly selective and therefore suitable for driving innate behaviors, whereas KCs provide a more general sparse representation of odors suitable for forming learned behavioral associations. Our results indicate that the transformation from ORN to PN firing rates in the antennal lobe equalizes the magnitudes of and decorrelates responses to different odors through feedforward nonlinearities and lateral suppression within the circuitry of the antennal lobe, and we study how these two components affect LHN and KC responses.antennal lobe | decorrelation | lateral horn | normalization | olfaction I n the olfactory system, as in other sensory systems, signals from primary receptors are processed and transformed before being relayed to higher brain areas. In Drosophila melanogaster, olfactory receptor neurons (ORNs) located in the antennae and maxillary palps synapse onto projection neurons (PNs) within the glomeruli of the antennal lobes (Fig. S1). ORNs expressing a given receptor converge on an anatomically invariant glomerulus. PNs innervate a single glomerulus and thus receive their primary input from ORNs expressing the same olfactory receptor (1), although crossglomerular interactions mediated by interneurons are also present (2-5). The PNs send their axons to two distinct regions of the fly brain, the lateral horn and the mushroom body. By constructing models of neurons in these regions, we study the effects of the transformations arising from circuitry within the antennal lobe on the capacity of neurons in the lateral horn and the mushroom body to represent and discriminate odors.Any functional interpretation of the transformation from ORN to PN responses depends on the nature of the processing being performed by the third-order neurons that receive PN input. The lateral horn and mushroom body appear to be involved in different forms of sensory processing. The lateral horn is believed to be important in generating innate behaviors (6), including those elicited by pheromones (7). PN projections to lateral horn neurons (LHNs) are spatially stereotyped (8, 9) and clustered (10), suggesting that circuits in this region may be "hardwired" for the detection of specific odors that elicit innate behavioral responses. The mushroom body is implicated in decision making (11) and in the formation of associative memories (12, 13). Both calcium imaging (14) and electrophysiology (15) indicate that the responses of Kenyon cell (KCs) in the mushroom body are sparse, with e...

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Representations of Odor in the Piriform Cortex

Cited by 538 publications

References 51 publications

Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling

Olfactory projectome in the zebrafish forebrain revealed by genetic single-neuron labelling

Perceptual convergence of multi-component mixtures in olfaction implies an olfactory white

Generating sparse and selective third-order responses in the olfactory system of the fly

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