Decoding olfaction in Drosophila

Keller, Andreas; Vosshall, Leslie B.

doi:10.1016/s0959-4388(03)00011-4

Cited by 47 publications

(21 citation statements)

References 54 publications

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“…5). Consistent with molecular evidence that olfactory neurons expressing homologous odorant receptors project to neighboring glomeruli (Tsuboi et al, 1999), support for spatially organized odor representations comes from numerous studies in widely differing species (for review, see Christensen and Hildebrand, 2002;Korsching, 2002;Keller and Vosshall, 2003). Our population data now provide direct evidence that the representations of nonpheromonal olfactory stimuli involve a combinatorial pattern of both excitatory and inhibitory responses distributed across each coding ensemble.…”

Section: Discussionsupporting

confidence: 83%

Spatial and Temporal Organization of Ensemble Representations for Different Odor Classes in the Moth Antennal Lobe

2004

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In the insect antennal lobe, odor discrimination depends on the ability of the brain to read neural activity patterns across arrays of uniquely identifiable olfactory glomeruli. Less is understood about the complex temporal dynamics and interglomerular interactions that underlie these spatial patterns. Using neural-ensemble recording, we show that the evoked firing patterns within and between groups of glomeruli are odor dependent and organized in both space and time. Simultaneous recordings from up to 15 units per ensemble were obtained from four zones of glomerular neuropil in response to four classes of odorants: pheromones, monoterpenoids, aromatics, and aliphatics. Each odor class evoked a different pattern of excitation and inhibition across recording zones. The excitatory response field for each class was spatially defined, but inhibitory activity was spread across the antennal lobe, reflecting a center-surround organization. Some chemically related odorants were not easily distinguished by their spatial patterns, but each odorant evoked transient synchronous firing across a uniquely different subset of ensemble units. Examination of 535 cell pairs revealed a strong relationship between their recording positions, temporal correlations, and similarity of odor response profiles. These findings provide the first definitive support for a nested architecture in the insect olfactory system that uses both spatial and temporal coordination of firing to encode chemosensory signals. The spatial extent of the representation is defined by a stereotyped focus of glomerular activity for each odorant class, whereas the transient temporal correlations embedded within the ensemble provide a second coding dimension that can facilitate discrimination between chemically similar volatiles.

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Section: Discussionsupporting

confidence: 83%

Spatial and Temporal Organization of Ensemble Representations for Different Odor Classes in the Moth Antennal Lobe

2004

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“…Recent studies have illuminated the development, morphology, and physiology of Drosophila ORNs and PNs (Keller and Vosshall, 2003;. Drosophila LNs, in contrast, have not received much attention.…”

Section: Resultsmentioning

confidence: 99%

Role of GABAergic Inhibition in Shaping Odor-Evoked Spatiotemporal Patterns in theDrosophilaAntennal Lobe

Wilson¹,

Laurent²

2005

J. Neurosci.

438

534

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Drosophila olfactory receptor neurons project to the antennal lobe, the insect analog of the mammalian olfactory bulb. GABAergic synaptic inhibition is thought to play a critical role in olfactory processing in the antennal lobe and olfactory bulb. However, the properties of GABAergic neurons and the cellular effects of GABA have not been described in Drosophila, an important model organism for olfaction research. We have used whole-cell patch-clamp recording, pharmacology, immunohistochemistry, and genetic markers to investigate how GABAergic inhibition affects olfactory processing in the Drosophila antennal lobe. We show that many axonless local neurons (LNs) in the adult antennal lobe are GABAergic. GABA hyperpolarizes antennal lobe projection neurons (PNs) via two distinct conductances, blocked by a GABA A -and GABA B -type antagonist, respectively. Whereas GABA A receptors shape PN odor responses during the early phase of odor responses, GABA B receptors mediate odor-evoked inhibition on longer time scales. The patterns of odor-evoked GABA B -mediated inhibition differ across glomeruli and across odors. Finally, we show that LNs display broad but diverse morphologies and odor preferences, suggesting a cellular basis for odor-and glomerulus-dependent patterns of inhibition. Together, these results are consistent with a model in which odors elicit stimulus-specific spatial patterns of GABA release, and as a result, GABAergic inhibition increases the degree of difference between the neural representations of different odors.

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“…Much progress has been attained to identify olfactory receptor genes in Drosophila (Vosshall et al ., 2000) and to characterize odor coding in the primary olfactory center (the antennal lobe) in Drosophila (Keller and Vosshall, 2003;Wang et al, 2003), honeybees (Sachse and Galizia, 2003), moths (Daly et al ., 2004) and locusts (Stopfer et al ., 2003). The results provide solid basis for future studies of odor processing at a more central level.…”

Section: Information Processing In the Antennal Lobementioning

confidence: 99%