The Functional Logic of Odor Information Processing in the Drosophila Antennal Lobe

2021 ◽  
Author(s):  
Aurel A Lazar ◽  
Tingkai Liu ◽  
Chung-Heng Yeh
Keyword(s):  
Information Processing ◽  
Steady State ◽  
Antennal Lobe ◽  
Stable Steady State ◽  
Projection Neurons ◽  
Olfactory Pathway ◽  
State Behavior ◽  
Key Characteristics ◽  
Functional Logic ◽  
Event Based

In the early olfactory pathway of Drosophila, Olfactory Sensory Neurons (OSNs) multiplicatively encode the odorant identity and the concentration profile. Projection Neurons (PNs) responses in the Antennal Lobe (AL), in turn, exhibit strong transients at odorant onset/offset and stable steady-state behavior. What is the functional logic the of diverse set of Local Neurons (LNs) in the AL Addressing this question may shed light on the key characteristics of odor information processing in the AL, and odorant recognition and olfactory associative learning in the downstream neuropils of the early olfactory system. To address the computation performed by each LN type, we exhaustively evaluated all circuit configurations of the Antennal Lobe. We found that, across model parameterizations, presynaptic inhibition of the OSN-to-PN synapse is essential for odorant identity recovery in steady-state, while postsynaptic excitation and inhibition facilitate on-/off-set event detection. The onset and offset events indicate changing odorant identities, and together with the identity recovery in steady-state, suggest that the AL is an event-based odorant identity recovery processor.

Direct and glia-mediated effects of GABA on development of central olfactory neurons

2011 ◽  
Vol 7 (2-4) ◽  
pp. 143-161
Author(s):  
Heather S. Mallory ◽  
Nicholas J. Gibson ◽  
Jon H. Hayashi ◽  
Alan J. Nighorn ◽  
Lynne A. Oland
Keyword(s):  
Glial Cells ◽  
Antennal Lobe ◽  
Neuronal Morphology ◽  
Projection Neurons ◽  
Olfactory Pathway ◽  
Mediated Effects ◽  
Local Interneurons ◽  
Outward Currents ◽  
Olfactory Glomeruli

Previously studied for its role in processing olfactory information in the antennal lobe, GABA also may shape development of the olfactory pathway, acting either through or on glial cells. Early in development, the dendrites of GABAergic neurons extend to the glial border that surrounds the nascent olfactory lobe neuropil. These neuropil glia express both GABAA and GABAB receptors, about half of the glia in acute cultures responded to GABA with small outward currents, and about a third responded with small transient increases in intracellular calcium. The neuronal classes that express GABA in vivo, the local interneurons and a subset of projection neurons, also do so in culture. Exposure to GABA in culture increased the size and complexity of local interneurons, but had no effect on glial morphology. The presence of glia alone did not affect neuronal morphology, but in the presence of both glia and GABA, the growth-enhancing effects of GABA on cultured antennal lobe neurons were eliminated. Contact between the glial cells and the neurons was not necessary. Operating in vivo, these antagonistic effects, one direct and one glia mediated, could help to sculpt the densely branched, tufted arbors that are characteristic of neurons innervating olfactory glomeruli.

scholarly journals Neuronal architecture of the second-order CO2 pathway in the brain of a noctuid moth

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
X. Chu ◽  
P. KC ◽  
E. Ian ◽  
P. Kvello ◽  
Y. Liu ◽  
...  
Keyword(s):  
Antennal Lobe ◽  
The Other ◽  
Projection Neurons ◽  
Target Area ◽  
Learning Mechanisms ◽  
Olfactory Pathway ◽  
Lateral Horn ◽  
Noctuid Moth ◽  
Comprehensive Knowledge ◽  
Plant Odor

AbstractMany insects possess the ability to detect fine fluctuations in the environmental CO2 concentration. In herbivorous species, plant-emitted CO2, in combination with other sensory cues, affect many behaviors including foraging and oviposition. In contrast to the comprehensive knowledge obtained on the insect olfactory pathway in recent years, we still know little about the central CO2 system. By utilizing intracellular labeling and mass staining, we report the neuroanatomy of projection neurons connected with the CO2 sensitive antennal-lobe glomerulus, the labial pit organ glomerulus (LPOG), in the noctuid moth, Helicoverpa armigera. We identified 15 individual LPOG projection neurons passing along different tracts. Most of these uniglomerular neurons terminated in the lateral horn, a previously well-described target area of plant-odor projection neurons originating from the numerous ordinary antennal-lobe glomeruli. The other higher-order processing area for odor information, the calyces, on the other hand, was weakly innervated by the LPOG neurons. The overlapping LPOG terminals in the lateral horn, which is considered important for innate behavior in insects, suggests the biological importance of integrating the CO2 input with plant odor information while the weak innervation of the calyces indicates the insignificance of this ubiquitous cue for learning mechanisms.

scholarly journals Classification of odorants across layers in locust olfactory pathway

2016 ◽  
Vol 115 (5) ◽  
pp. 2303-2316 ◽  
Author(s):  
Pavel Sanda ◽  
Tiffany Kee ◽  
Nitin Gupta ◽  
Mark Stopfer ◽  
Maxim Bazhenov
Keyword(s):  
Antennal Lobe ◽  
Error Rates ◽  
Classification Error ◽  
Mushroom Bodies ◽  
Insect Brain ◽  
Projection Neurons ◽  
Olfactory Pathway ◽  
Lateral Horn ◽  
Odor Classification

Olfactory processing takes place across multiple layers of neurons from the transduction of odorants in the periphery, to odor quality processing, learning, and decision making in higher olfactory structures. In insects, projection neurons (PNs) in the antennal lobe send odor information to the Kenyon cells (KCs) of the mushroom bodies and lateral horn neurons (LHNs). To examine the odor information content in different structures of the insect brain, antennal lobe, mushroom bodies and lateral horn, we designed a model of the olfactory network based on electrophysiological recordings made in vivo in the locust. We found that populations of all types (PNs, LHNs, and KCs) had lower odor classification error rates than individual cells of any given type. This improvement was quantitatively different from that observed using uniform populations of identical neurons compared with spatially structured population of neurons tuned to different odor features. This result, therefore, reflects an emergent network property. Odor classification improved with increasing stimulus duration: for similar odorants, KC and LHN ensembles reached optimal discrimination within the first 300–500 ms of the odor response. Performance improvement with time was much greater for a population of cells than for individual neurons. We conclude that, for PNs, LHNs, and KCs, ensemble responses are always much more informative than single-cell responses, despite the accumulation of noise along with odor information.

Implications from Microcircuits of a Moth’s Antennal Lobe for Olfactory Information Processing

2017 ◽  
pp. 333-344
Author(s):  
Hong Lei ◽  
Lynne A. Oland ◽  
Jeffery A. Riffell ◽  
Aaron Beyerlein ◽  
John G. Hildebrand
Keyword(s):  
Information Processing ◽  
Antennal Lobe ◽  
Neural Circuits ◽  
Functional Organization ◽  
Physiological Responses ◽  
Projection Neurons ◽  
Natural Behavior ◽  
Odor Cues ◽  
Ongoing Work ◽  
Output Neurons

Olfactory circuits of all animals face a common challenge of extracting meaningful odor cues from background odors. This chapter summarizes what the authors have learned from their ongoing work toward the goal of understanding how the neural circuits in a moth’s antennal lobe (AL) determine diverse physiological responses that ultimately mediate the animal’s natural behavior. The text describes the different types of cellular elements that participate in the glomerular circuitry, focuses on the functional organization of these elements, and attempts to explain observed physiological responses in the context of behavior using the understood operating principles of the AL circuits. For convenience, the connections from the perspective of the main output neurons of the circuitry, uniglomerular projection neurons (uPNs), are described.

scholarly journals Results of the Marine Ice Sheet Model Intercomparison Project, MISMIP

2012 ◽  
Vol 6 (3) ◽  
pp. 573-588 ◽  
Author(s):  
F. Pattyn ◽  
C. Schoof ◽  
L. Perichon ◽  
R. C. A. Hindmarsh ◽  
E. Bueler ◽  
...  
Keyword(s):  
Steady State ◽  
Adaptive Mesh Refinement ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Stable Steady State ◽  
Fixed Grid ◽  
Approximate Analytical Solutions ◽  
Grounding Line ◽  
Intercomparison Project ◽  
Line Positions

Abstract. Predictions of marine ice-sheet behaviour require models that are able to robustly simulate grounding line migration. We present results of an intercomparison exercise for marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no effects of lateral buttressing). Unique steady state grounding line positions exist for ice sheets on a downward sloping bed, while hysteresis occurs across an overdeepened bed, and stable steady state grounding line positions only occur on the downward-sloping sections. Models based on the shallow ice approximation, which does not resolve extensional stresses, do not reproduce the approximate analytical results unless appropriate parameterizations for ice flux are imposed at the grounding line. For extensional-stress resolving "shelfy stream" models, differences between model results were mainly due to the choice of spatial discretization. Moving grid methods were found to be the most accurate at capturing grounding line evolution, since they track the grounding line explicitly. Adaptive mesh refinement can further improve accuracy, including fixed grid models that generally perform poorly at coarse resolution. Fixed grid models, with nested grid representations of the grounding line, are able to generate accurate steady state positions, but can be inaccurate over transients. Only one full-Stokes model was included in the intercomparison, and consequently the accuracy of shelfy stream models as approximations of full-Stokes models remains to be determined in detail, especially during transients.

Morphology and physiology of antennal lobe projection neurons in the hawkmoth Agrius convolvuli

2017 ◽  
Vol 98 ◽  
pp. 214-222 ◽  
Author(s):  
Takuya Nirazawa ◽  
Takeshi Fujii ◽  
Yoichi Seki ◽  
Shigehiro Namiki ◽  
Tomoki Kazawa ◽  
...  
Keyword(s):  
Antennal Lobe ◽  
Projection Neurons
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