Excitatory Local Circuits and Their Implications for Olfactory Processing in the Fly Antennal Lobe

Shang, Yuhua; Claridge‐Chang, Adam; Sjulson, Lucas; Pypaert, Marc; Miesenböck, Gero

doi:10.1016/j.cell.2006.12.034

Cited by 326 publications

(432 citation statements)

References 55 publications

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“…As a result, detection and discrimination thresholds are increased as evidenced by psychophysical data from A. mellifera and M. sexta indicating that the salient odour signal is lost (Hosler et al 2000, Mwilaria et al 2008. In D. melanogaster, the increased output from the processing channels has been linked to the activity of excitatory cholinergic LN connections between glomeruli (Olsen et al 2007, Root et al 2007, Shang et al 2007, driven by direct monosynaptic input from ORNs (Kazama and Wilson 2008). This type of cholinergic connection has, so far, neither been supported physiologically nor immunohistologically in other insect olfactory systems (Homberg and Müller 1999).…”

Section: Intra-and Interglomerular Synaptic Interactions In the Antenmentioning

confidence: 87%

“…the olfactory information will faithfully be transmitted to higher brain centres, as suggested by Ng et al (2003), Root et al (2007) and Wang et al (2003). Accumulating evidence over the last few years from different insects, however, emphasises that LNs that tend to have broad multiglomerular ramifications ( Figure 7A), and thus provide a scaffold for crosstalk between channels, play a major role in shaping the output response of the processing channels (reviewed by , see also Bhandawat et al 2007, Olsen and Wilson 2008, Olsen et al 2007, Root et al 2007, Shang et al 2007, Wilson and Laurent 2005. In addition, intraglomerular events appear to have a significant influence on these processes (Bhandawat et al 2007, Christensen et al 2000, Kazama and Wilson 2008, Olsen and Wilson 2008, Wilson et al 2004).…”

Section: Intra-and Interglomerular Synaptic Interactions In the Antenmentioning

confidence: 99%

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Olfaction in vector-host interactions

Takken¹,

Knols²

2010

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Section: Intra-and Interglomerular Synaptic Interactions In the Antenmentioning

confidence: 87%

Section: Intra-and Interglomerular Synaptic Interactions In the Antenmentioning

confidence: 99%

Olfaction in vector-host interactions

Takken¹,

Knols²

2010

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“…However, this is unlikely, because arborizations of Ͼ1 GH146-positive PN in a single larval AL glomerulus were never observed (19). Second, interglomerular excitatory cholinergic connections in the AL, which apparently follow defined routes, broaden the response of PNs relative to that of OSNs (5,6,25). Olsen et al (5) detected broadening of input from single adult OSNs to many more PNs than the one or two observed here, in the form of depolarization of most PNs tested, from a subset of the entire PN population.…”

Section: Discussionmentioning

confidence: 99%

“…Projection neurons (PNs) then carry olfactory information from single AL glomeruli to the higher brain, the MB, and the lateral horn. However, excitatory interneurons that innervate multiple AL glomeruli lead to broadening of PN specificity compared with OSNs (5,6). PNs then connect to Kenyon cells (KCs) in the calyx of the MB, where the representation of odor qualities is radically transformed; individual KCs respond much more selectively to odors than do either OSNs or PNs (7)(8)(9).…”

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confidence: 99%

Localized olfactory representation in mushroom bodies of Drosophila larvae

Masuda-Nakagawa

Gendre

O’Kane

et al. 2009

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

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Odor discrimination in higher brain centers is essential for behavioral responses to odors. One such center is the mushroom body (MB) of insects, which is required for odor discrimination learning. The calyx of the MB receives olfactory input from projection neurons (PNs) that are targets of olfactory sensory neurons (OSNs) in the antennal lobe (AL). In the calyx, olfactory information is transformed from broadly-tuned representations in PNs to sparse representations in MB neurons (Kenyon cells). However, the extent of stereotypy in olfactory representations in the calyx is unknown. Using the anatomically-simple larval olfactory system of Drosophila in which odor ligands for the entire set of 21 OSNs are known, we asked how odor identity is represented in the MB calyx. We first mapped the projections of all larval OSNs in the glomeruli of the AL, and then followed the connections of individual PNs from the AL to different calyx glomeruli. We thus established a comprehensive olfactory map from OSNs to a higher olfactory association center, at a single-cell level. Stimulation of single OSNs evoked strong neuronal activity in 1 to 3 calyx glomeruli, showing that broadening of the strongest PN responses is limited to a few calyx glomeruli. Stereotypic representation of single OSN input in calyx glomeruli provides a mechanism for MB neurons to detect and discriminate olfactory cues.calyx ͉ genetically-encoded calcium indicator ͉ olfactory sensory neurons ͉ projection neurons W e now understand much about how odor information is detected and conveyed to the brain by sensory neurons, but less about how this information is represented in higher brain centers to influence behavioral outputs. The mushroom body (MB) of insects, which in Drosophila is essential for odor discrimination learning, provides a model to understand olfactory coding in higher association centers (1, 2). In the periphery, odor identity is detected by sets of olfactory sensory neurons (OSNs) whose specificities are determined by the olfactory receptor (OR) that they express (3, 4). OSNs that express the same OR converge on defined glomeruli in the first olfactory center of the brain, the antennal lobe (AL), analogously to the convergence of OSNs on olfactory bulb glomeruli in mammals. Projection neurons (PNs) then carry olfactory information from single AL glomeruli to the higher brain, the MB, and the lateral horn. However, excitatory interneurons that innervate multiple AL glomeruli lead to broadening of PN specificity compared with OSNs (5, 6). PNs then connect to Kenyon cells (KCs) in the calyx of the MB, where the representation of odor qualities is radically transformed; individual KCs respond much more selectively to odors than do either OSNs or PNs (7-9).The extent of stereotypy in olfactory processing in the calyx has been a matter of debate, in contrast to the clearly stereotypic connections between OSNs and PNs in the AL. In Drosophila adults, apparently stereotypic projections of PNs and KCs have been defined anatomically only at the leve...

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“…The activity of ORNs, either excitation or inhibition, provides behaviorally relevant information about odorants such as their identity, concentration, and source. The information transduced by an ORN is processed in the antennal lobe (12,13) and sent via PNs to the mushroom bodies, which are believed to be centers for olfactory learning and memory (14,15).…”

mentioning

confidence: 99%

Post-eclosion odor experience modifies olfactory receptor neuron coding in Drosophila

Iyengar

Chakraborty

Goswami

et al. 2010

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

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Olfactory responses of Drosophila undergo pronounced changes after eclosion. The flies develop attraction to odors to which they are exposed and aversion to other odors. Behavioral adaptation is correlated with changes in the firing pattern of olfactory receptor neurons (ORNs). In this article, we present an information-theoretic analysis of the firing pattern of ORNs. Flies reared in a synthetic odorless medium were transferred after eclosion to three different media: (i) a synthetic medium relatively devoid of odor cues, (ii) synthetic medium infused with a single odorant, and (iii) complex cornmeal medium rich in odors. Recordings were made from an identified sensillum (type II), and the Jensen-Shannon divergence (D JS ) was used to assess quantitatively the differences between ensemble spike responses to different odors. Analysis shows that prolonged exposure to ethyl acetate and several related esters increases sensitivity to these esters but does not improve the ability of the fly to distinguish between them. Flies exposed to cornmeal display varied sensitivity to these odorants and at the same time develop greater capacity to distinguish between odors. Deprivation of odor experience on an odorless synthetic medium leads to a loss of both sensitivity and acuity. Rich olfactory experience thus helps to shape the ORNs response and enhances its discriminative power. The experiments presented here demonstrate an experience-dependent adaptation at the level of the receptor neuron.imaginal conditioning | sensory adaptation | odor imprinting | JensenShannon divergence | chemo receptor tuning O lfaction in the fruit fly, Drosophila melanogaster, is crucial for a variety of behaviors, including associative learning (1, 2), courtship (3), foraging (4), and flight (5, 6). Odorants are detected by approximately 1,300 olfactory receptor neurons (ORNs), which are housed in sensilla on the third antennal segment and individually express one of approximately 50 functional odor receptors in adults (7-9). All ORNs expressing the same olfactory receptor project to one of approximately 50 glomeruli in the antennal lobe, where they synapse with a set of projection neurons (PNs) (10, 11). The activity of ORNs, either excitation or inhibition, provides behaviorally relevant information about odorants such as their identity, concentration, and source. The information transduced by an ORN is processed in the antennal lobe (12, 13) and sent via PNs to the mushroom bodies, which are believed to be centers for olfactory learning and memory (14, 15).Experience-dependent modifiability (i.e., plasticity) of olfactory representation at the level of the central nervous system is well known (2,16,17). Relatively little attention has been paid to long-term changes in sensory neuron activity resulting from odor experiences. It was previously shown that exposure of newly born imago to a particular set of odorants alters their responses to these odors (18,19). The flies develop an attraction to the chemicals to which they are exposed and an av...

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Excitatory Local Circuits and Their Implications for Olfactory Processing in the Fly Antennal Lobe

Cited by 326 publications

References 55 publications

Olfaction in vector-host interactions

Olfaction in vector-host interactions

Localized olfactory representation in mushroom bodies of Drosophila larvae

Post-eclosion odor experience modifies olfactory receptor neuron coding in Drosophila

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