Olfactory Information Processing in Moths

Haupt, Stephan Shuichi; Sakurai, Takeshi; Namiki, Shigehiro; Kazawa, Tomoki; Kanzaki, Ryohei

doi:10.1201/9781420071993-c3

Cited by 19 publications

(21 citation statements)

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“…Due to the moth’s exquisite sense of smell, combined with its relatively simple and accessible nervous system, this group of nocturnal insects has been appreciated in a body of research essential for understanding chemosensory processing principles. The moth olfactory system has therefore been described in several previous works (reviewed by Anton and Homberg, 1999 ; Haupt et al, 2010 ; Martin et al, 2011 ). As in other insects, olfactory sensory neurons covering the antenna of the moth project directly to the primary olfactory center of the brain, the antennal lobe (AL) - which is the analog to the mammalian olfactory bulb.…”

Section: Introductionmentioning

confidence: 99%

Individual Neurons Confined to Distinct Antennal-Lobe Tracts in the Heliothine Moth: Morphological Characteristics and Global Projection Patterns

et al. 2016

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To explore fundamental principles characterizing chemosensory information processing, we have identified antennal-lobe projection neurons in the heliothine moth, including several neuron types not previously described. Generally, odor information is conveyed from the primary olfactory center of the moth brain, the antennal lobe, to higher brain centers via projection neuron axons passing along several parallel pathways, of which the medial, mediolateral, and lateral antennal-lobe tract are considered the classical ones. Recent data have revealed the projections of the individual tracts more in detail demonstrating three main target regions in the protocerebrum; the calyces are innervated mainly by the medial tract, the superior intermediate protocerebrum by the lateral tract exclusively, and the lateral horn by all tracts. In the present study, we have identified, via iontophoretic intracellular staining combined with confocal microscopy, individual projection neurons confined to the tracts mentioned above, plus two additional ones. Further, using the visualization software AMIRA, we reconstructed the stained neurons and registered the models into a standard brain atlas, which allowed us to compare the termination areas of individual projection neurons both across and within distinct tracts. The data demonstrate a morphological diversity of the projection neurons within distinct tracts. Comparison of the output areas of the neurons confined to the three main tracts in the lateral horn showed overlapping terminal regions for the medial and mediolateral tracts; the lateral tract neurons, on the contrary, targeted mostly other output areas in the protocerebrum.

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Section: Introductionmentioning

confidence: 99%

Individual Neurons Confined to Distinct Antennal-Lobe Tracts in the Heliothine Moth: Morphological Characteristics and Global Projection Patterns

et al. 2016

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“…MGC-PNs are classified as specialists or generalists according to their responses to single compounds (18,19). Generalist PNs are excited by BAL and C15, whereas specialist PNs are excited by one compound and inhibited by the other (19,20). BAL or C15 specialist PNs fire synchronously, and their synchronization is sharpened by the presence of both components in the pheromone mixture (21).…”

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confidence: 99%

Interaction of cellular and network mechanisms for efficient pheromone coding in moths

Belmabrouk

Nowotny

Rospars³

et al. 2011

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

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Sensory systems, both in the living and in machines, have to be optimized with respect to their environmental conditions. The pheromone subsystem of the olfactory system of moths is a particularly well-defined example in which rapid variations of odor content in turbulent plumes require fast, concentration-invariant neural representations. It is not clear how cellular and network mechanisms in the moth antennal lobe contribute to coding efficiency. Using computational modeling, we show that intrinsic potassium currents (I A and I SK ) in projection neurons may combine with extrinsic inhibition from local interneurons to implement a dual latency code for both pheromone identity and intensity. The mean latency reflects stimulus intensity, whereas latency differences carry concentration-invariant information about stimulus identity. In accordance with physiological results, the projection neurons exhibit a multiphasic response of inhibition-excitation-inhibition. Together with synaptic inhibition, intrinsic currents I A and I SK account for the first and second inhibitory phases and contribute to a rapid encoding of pheromone information. The first inhibition plays the role of a reset to limit variability in the time to first spike. The second inhibition prevents responses of excessive duration to allow tracking of intermittent stimuli. To prevent crossattraction, the pheromone blend is distinguishable not only by the identity of the individual components but also by their precise ratio. Behavioral experiments revealed that male moths are tuned to the specific proportions emitted by their conspecific females. Slight changes in component ratios, for example, can inhibit the anemotactic response of males of one species, while attracting males from another species (4-6). Pheromones are passively transported in the air and mixed by atmospheric turbulence, and therefore, during flight, male moths encounter pheromone filaments with all components present in the same proportions as released (7) but over a broad range of concentrations (8, 9). In the race for mating, flying male moths have to solve a difficult pattern recognition problem (i.e., recognize, in real time, pheromone compounds and their proportions independently of blend concentration). To do so, the information delivered by olfactory receptor neurons (ORNs) is integrated in the antennal lobe by a neural network involving inhibitory local neurons (LNs) and excitatory projection neurons (PNs). All synaptic connections between these neurons take place in a subset of enlarged, sexually dimorphic glomeruli, the macroglomerular complex (MGC). The circuitry of the MGC is similar to the one of the generalist olfactory subsystem. In the generalist subsystem, prolonged odor stimulations (up to several seconds) create local field potential oscillations and transient PN assemblies that synchronize to them and evolve in time in a stimulus-specific manner (10-12). Using time in such a manner as a coding dimension, however, poses a serious problem for a flying insect. In nat...

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“…Each of these component-specific MGC glomeruli then sends output through projection neurons (PNs) to higher brain centres in the protocerebrum (mushroom bodies, lateral horn) where olfactory information is further processed (Anton and Hansson, 1995). Such centres are believed to provide direct or indirect input to the lateral accessory lobes, where an output signal appears to be generated and transmitted to the thoracic ganglia through descending neurons (Kanzaki et al, 1991a;Kanzaki et al, 1991b;Kanzaki and Shibuya, 1992; for a review, see Haupt et al, 2010). Ultimately, the resulting coordinated activity of thoracic flight muscles by motor neurons leads to the characteristic orientation flight towards the pheromone source (Cardé and Willis, 2008).…”

Section: Introductionmentioning

confidence: 99%

Experience-dependent modulation of antennal sensitivity and input to antennal lobes in male moths (Spodoptera littoralis) pre-exposed to sex pheromone

Guerrieri

Gemeno

Monsempes

et al. 2012

Journal of Experimental Biology

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SUMMARYSex pheromones are intraspecific olfactory signals emitted by one sex to attract a potential mating partner. Behavioural responses to sex pheromones are generally highly stereotyped. However, they can be modulated by experience, as male moths previously exposed to female sex pheromone respond with a lower threshold upon further detection, even after long delays. Here, we address the question of the neural mechanisms underlying such long-term modulation. As previous work has shown increased responses to pheromone in central olfactory neurons, we asked whether brief exposure to the pheromone increases input activity from olfactory receptor neurons. Males pre-exposed to sex pheromone exhibited increased peripheral sensitivity to the main pheromone component. Among nine antennal genes targeted as putatively involved in pheromone reception, one encoding a pheromone-binding protein showed significant upregulation upon exposure. In the primary olfactory centre (antennal lobe), the neural compartment processing the main pheromone component was enlarged after a brief pheromone exposure, thus suggesting enduring structural changes. We hypothesise that higher peripheral sensitivity following pre-exposure leads to increased input to the antennal lobe, thus contributing to the structural and functional reorganization underlying a stable change in behaviour.

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Olfactory Information Processing in Moths

Cited by 19 publications

References 0 publications

Individual Neurons Confined to Distinct Antennal-Lobe Tracts in the Heliothine Moth: Morphological Characteristics and Global Projection Patterns

Individual Neurons Confined to Distinct Antennal-Lobe Tracts in the Heliothine Moth: Morphological Characteristics and Global Projection Patterns

Interaction of cellular and network mechanisms for efficient pheromone coding in moths

Experience-dependent modulation of antennal sensitivity and input to antennal lobes in male moths (Spodoptera littoralis) pre-exposed to sex pheromone

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