scholarly journals A resource for the Drosophila antennal lobe provided by the connectome of glomerulus VA1v

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Jane Anne Horne ◽  
Carlie Langille ◽  
Sari McLin ◽  
Meagan Wiederman ◽  
Zhiyuan Lu ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Olfactory Receptor ◽  
Antennal Lobe ◽  
Olfactory Receptor Neurons ◽  
Projection Neurons ◽  
Sexually Dimorphic ◽  
Genetic Screens ◽  
Local Interneurons ◽  
Receptor Neurons ◽  
The Right

Using FIB-SEM we report the entire synaptic connectome of glomerulus VA1v of the right antennal lobe in Drosophila melanogaster. Within the glomerulus we densely reconstructed all neurons, including hitherto elusive local interneurons. The fruitless-positive, sexually dimorphic VA1v included >11,140 presynaptic sites with ~38,050 postsynaptic dendrites. These connected input olfactory receptor neurons (ORNs, 51 ipsilateral, 56 contralateral), output projection neurons (18 PNs), and local interneurons (56 of >150 previously reported LNs). ORNs are predominantly presynaptic and PNs predominantly postsynaptic; newly reported LN circuits are largely an equal mixture and confer extensive synaptic reciprocity, except the newly reported LN2V with input from ORNs and outputs mostly to monoglomerular PNs, however. PNs were more numerous than previously reported from genetic screens, suggesting that the latter failed to reach saturation. We report a matrix of 192 bodies each having >50 connections; these form 88% of the glomerulus’ pre/postsynaptic sites.

scholarly journals Cholinergic calcium responses in cultured antennal lobe neurons of the migratory locust

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gregor A. Bergmann ◽  
Gerd Bicker
Keyword(s):  
Olfactory Receptor ◽  
Intracellular Signaling ◽  
Antennal Lobe ◽  
Locusta Migratoria ◽  
Cytosolic Calcium ◽  
Olfactory Receptor Neurons ◽  
Future Research ◽  
Migratory Locust ◽  
Local Interneurons ◽  
Receptor Neurons

AbstractLocusts are advantageous organisms to elucidate mechanisms of olfactory coding at the systems level. Sensory input is provided by the olfactory receptor neurons of the antenna, which send their axons into the antennal lobe. So far, cellular properties of neurons isolated from the circuitry of the olfactory system, such as transmitter-induced calcium responses, have not been studied. Biochemical and immunocytochemical investigations have provided evidence for acetylcholine as classical transmitter of olfactory receptor neurons. Here, we characterize cell cultured projection and local interneurons of the antennal lobe by cytosolic calcium imaging to cholinergic stimulation. We bulk loaded the indicator dye Cal-520 AM in dissociated culture and recorded calcium transients after applying cholinergic agonists and antagonists. The majority of projection and local neurons respond with increases in calcium levels to activation of both nicotinic and muscarinic receptors. In local interneurons, we reveal interactions lasting over minutes between intracellular signaling pathways, mediated by muscarinic and nicotinic receptor stimulation. The present investigation is pioneer in showing that Cal-520 AM readily loads Locusta migratoria neurons, making it a valuable tool for future research in locust neurophysiology, neuropharmacology, and neurodevelopment.

scholarly journals Cholinergic calcium responses in cultured antennal lobe neurons of the migratory locust

2021 ◽  
Author(s):  
Gregor A. Bergmann ◽  
Gerd Bicker
Keyword(s):  
Olfactory Receptor ◽  
Intracellular Signaling ◽  
Antennal Lobe ◽  
Locusta Migratoria ◽  
Cytosolic Calcium ◽  
Olfactory Receptor Neurons ◽  
Future Research ◽  
Migratory Locust ◽  
Local Interneurons ◽  
Receptor Neurons

AbstractLocusts are advantageous organisms to elucidate mechanisms of olfactory coding at the systems level. Sensory input is provided by the olfactory receptor neurons of the antenna, which send their axons into the antennal lobe. So far, cellular properties of neurons isolated from the circuitry of the olfactory system, such as transmitter-induced calcium responses, have not been studied. Biochemical and immunocytochemical investigations have provided evidence for acetylcholine as classical transmitter of olfactory receptor neurons. Here, we characterize cell cultured projection and local interneurons of the antennal lobe by cytosolic calcium imaging to cholinergic stimulation. We bulk loaded the indicator dye Cal-520 AM in dissociated culture and recorded calcium transients after applying cholinergic agonists and antagonists. The majority of projection and local neurons respond with increases in calcium levels to activation of both nicotinic and muscarinic receptors. In local interneurons, we reveal interactions lasting over minutes between intracellular signaling pathways, mediated by muscarinic and nicotinic receptor stimulation. The present investigation is pioneer in showing that Cal-520 AM readily loads Locusta migratoria neurons, making it a valuable tool for future research in locust neurophysiology, neuropharmacology, and neurodevelopment.

scholarly journals Concentration-Invariant Odor Representation in the Olfactory System by Presynaptic Inhibition

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Danke Zhang ◽  
Yuanqing Li ◽  
Si Wu
Keyword(s):  
Olfactory Receptor ◽  
Olfactory System ◽  
Olfactory Receptor Neurons ◽  
Projection Neurons ◽  
Invariant Representation ◽  
Odor Concentration ◽  
Presynaptic Site ◽  
Divisive Normalization ◽  
Receptor Neurons ◽  
Parameter Condition

The present study investigates a network model for implementing concentration-invariant representation for odors in the olfactory system. The network consists of olfactory receptor neurons, projection neurons, and inhibitory local neurons. Receptor neurons send excitatory inputs to projection neurons, which are modulated by the inhibitory inputs from local neurons. The modulation occurs at the presynaptic site from a receptor neuron to a projection one, leading to the operation of divisive normalization. The responses of local interneurons are determined by the total activities of olfactory receptor neurons. We find that with a proper parameter condition, the responses of projection neurons become effectively independent of the odor concentration. Simulation results confirm our theoretical analysis.

Olfactory Representations by Drosophila Mushroom Body Neurons

2008 ◽  
Vol 99 (2) ◽  
pp. 734-746 ◽  
Author(s):  
Glenn C. Turner ◽  
Maxim Bazhenov ◽  
Gilles Laurent
Keyword(s):  
Olfactory Receptor ◽  
Mushroom Body ◽  
Temporal Integration ◽  
Activity Patterns ◽  
Olfactory Receptor Neurons ◽  
Projection Neurons ◽  
Contributing Factors ◽  
Receptor Neurons ◽  
Whole Cell Recordings

Learning and memory has been studied extensively in Drosophila using behavioral, molecular, and genetic approaches. These studies have identified the mushroom body as essential for the formation and retrieval of olfactory memories. We investigated odor responses of the principal neurons of the mushroom body, the Kenyon cells (KCs), in Drosophila using whole cell recordings in vivo. KC responses to odors were highly selective and, thus sparse, compared with those of their direct inputs, the antennal lobe projection neurons (PNs). We examined the mechanisms that might underlie this transformation and identified at least three contributing factors: excitatory synaptic potentials (from PNs) decay rapidly, curtailing temporal integration, PN convergence onto individual KCs is low (∼10 PNs per KC on average), and KC firing thresholds are high. Sparse activity is thought to be useful in structures involved in memory in part because sparseness tends to reduce representation overlaps. By comparing activity patterns evoked by the same odors across olfactory receptor neurons and across KCs, we show that representations of different odors do indeed become less correlated as they progress through the olfactory system.

scholarly journals Non-synaptic interactions between olfactory receptor neurons, a possible key feature of odor processing in insects

2020 ◽  
Author(s):  
Mario Pannunzi ◽  
Thomas Nowotny
Keyword(s):  
Lateral Inhibition ◽  
Olfactory Receptor ◽  
Olfactory System ◽  
Antennal Lobe ◽  
Olfactory Receptor Neurons ◽  
Inhibition Mechanism ◽  
Alternative Mechanism ◽  
Odor Processing ◽  
Synaptic Interactions ◽  
Receptor Neurons

AbstractWhen flies explore their environment, they encounter odors in complex, highly intermittent plumes. To navigate a plume and, for example, find food, flies must solve several tasks, including reliably identifying mixtures of odorants and discriminating odorant mixtures emanating from a single source from odorants emitted from separate sources and mixing in the air. Lateral inhibition in the antennal lobe is commonly understood to help solving these two tasks. With a computational model of the Drosophila olfactory system, we analyze the utility of an alternative mechanism for solving them: Non-synaptic (“ephaptic”) interactions (NSIs) between olfactory receptor neurons that are stereotypically co-housed in the same sensilla. For both tasks, NSIs improve the insect olfactory system and outperform the standard lateral inhibition mechanism in the antennal lobe. These results shed light, from an evolutionary perspective, on the role of NSIs, which are normally avoided between neurons, for instance by myelination.

Sensillum-specific, topographic projection patterns of olfactory receptor neurons in the antennal lobe of the cockroach Periplaneta americana

2012 ◽  
Vol 520 (8) ◽  
pp. 1687-1701 ◽  
Author(s):  
Hidehiro Watanabe ◽  
S. Shuichi Haupt ◽  
Hiroshi Nishino ◽  
Michiko Nishikawa ◽  
Fumio Yokohari
Keyword(s):  
Olfactory Receptor ◽  
Antennal Lobe ◽  
Periplaneta Americana ◽  
Olfactory Receptor Neurons ◽  
Receptor Neurons

scholarly journals EAG Responses Increase of Spodoptera littoralis Antennae after a Single Pheromone Pulse

2014 ◽  
Vol 9 (8) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Carmen Quero ◽  
Berta Vidal ◽  
Angel Guerrero
Keyword(s):  
Olfactory Receptor ◽  
Spodoptera Littoralis ◽  
Antennal Lobe ◽  
Life Time ◽  
Olfactory Receptor Neurons ◽  
Average Life ◽  
Antennal Response ◽  
Behavioral Sensitivity ◽  
Response Increase ◽  
Receptor Neurons

Increased behavioral sensitivity to the pheromone after brief exposure of the whole insect to the sex pheromone has been documented in antennal lobe neurons of Spodoptera littoralis. We investigated whether a brief stimulus of the major component of the pheromone on naïve antenna separated from the head increased the electroantennographic responses after successive stimulations at different times. The response increase was clear 30 min after the first stimulation, and this effect lasted at least 60 min, the average life time of the antenna. Our results suggest that the olfactory receptor neurons, and not only the neurons in the antennal lobe, may be involved in the increased antennal response after a single pheromone pulse.

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