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Giovanni C Galizia - One of the best experts on this subject based on the ideXlab platform.

  • data driven honeybee Antennal Lobe model suggests how stimulus onset asynchrony can aid odour segregation
    Brain Research, 2013
    Co-Authors: Thomas Nowotny, Giovanni C Galizia, Jacob S Stierle, Paul Szyszka
    Abstract:

    Insects have a remarkable ability to identify and track odour sources in multi-odour backgrounds. Recent behavioural experiments show that this ability relies on detecting millisecond stimulus asynchronies between odourants that originate from different sources. Honeybees, Apis mellifera , are able to distinguish mixtures where both odourants arrive at the same time (synchronous mixtures) from those where odourant onsets are staggered (asynchronous mixtures) down to an onset delay of only 6 ms. In this paper we explore this surprising ability in a model of the insects' primary olfactory brain area, the Antennal Lobe. We hypothesize that a winner-take-all inhibitory network of local neurons in the Antennal Lobe has a symmetry-breaking effect, such that the response pattern in projection neurons to an asynchronous mixture is different from the response pattern to the corresponding synchronous mixture for an extended period of time beyond the initial odourant onset where the two mixture conditions actually differ. The prolonged difference between response patterns to synchronous and asynchronous mixtures could facilitate odour segregation in downstream circuits of the olfactory pathway. We present a detailed data-driven model of the bee Antennal Lobe that reproduces a large data set of experimentally observed physiological odour responses, successfully implements the hypothesised symmetry-breaking mechanism and so demonstrates that this mechanism is consistent with our current knowledge of the olfactory circuits in the bee brain.

  • inhibitory connections in the honeybee Antennal Lobe are spatially patchy
    Journal of Neurophysiology, 2013
    Co-Authors: Cyrille C Girardin, Sabine Kreissl, Giovanni C Galizia
    Abstract:

    The olfactory system is a classical model for studying sensory processing. The first olfactory brain center [the olfactory bulb of vertebrates and the Antennal Lobe (AL) of insects] contains spheri...

  • olfactory sensor processing in neural networks lessons from modeling the fruit fly Antennal Lobe
    Frontiers in Neuroengineering, 2012
    Co-Authors: Henning J Proske, Marco K Wittmann, Giovanni C Galizia
    Abstract:

    The insect olfactory system can be a model for artificial olfactory devices. In particular, Drosophila melanogaster due to its genetic tractability has yielded much information about the design and function of such systems in biology. In this study we investigate possible network topologies to separate representations of odors in the primary olfactory neuropil, the Antennal Lobe. In particular we compare networks based on stochastic and homogeneous connection weight distributions to connectivities that are based on the input correlations between the glomeruli in the Antennal Lobe. We show that moderate homogeneous inhibition implements a soft winner-take-all mechanism when paired with realistic input from a database of odor responses in receptor cells. The sparseness of representations increases with stronger inhibition. Excitation, on the other hand, pushes the representation of odors closer together thus making them harder to distinguish. We further analyze the relationship between different inhibitory network topologies and the properties of the receptor responses to different odors. We show that realistic input from the database has a relatively high entropy of activation values over all odors and receptors compared to the theoretical maximum. Furthermore, under conditions in which the information in the input is artificially decreased, networks with heterogeneous topologies based on the similarity of glomerular response profiles perform best. These results indicate that in order to arrive at the most beneficial representation for odor discrimination it is important to finely tune the strength of inhibition in combination with taking into account the properties of the available sensors.

  • olfactory information processing in the drosophila Antennal Lobe anything goes
    The Journal of Neuroscience, 2008
    Co-Authors: Ana F Silbering, Ryuichi Okada, Kei Ito, Giovanni C Galizia
    Abstract:

    When an animal smells an odor, olfactory sensory neurons generate an activity pattern across olfactory glomeruli of the first sensory neuropil, the insect Antennal Lobe or the vertebrate olfactory bulb. Here, several networks of local neurons interact with sensory neurons and with output neurons--insect projection neurons, or vertebrate mitral/tufted cells. The extent and form of information processing taking place in these local networks has been subject of controversy. To investigate the role of local neurons in odor information processing we have used the calcium sensor G-CaMP to perform in vivo recordings of odor-evoked spatiotemporal activity patterns in five genetically defined neuron populations of the Antennal Lobe of Drosophila melanogaster: three distinct populations of local neurons (two GABAergic and one cholinergic), as well as sensory neurons and projection neurons. Odor-specific and concentration dependent spatiotemporal response patterns varied among neuron populations. Activity transfer differed along the olfactory pathway for different glomerulus-odor combinations: we found cases of profile broadening and of linear and complex transfer. Moreover, the discriminability between the odors also varied across neuron populations and was maximal in projection neurons. Discriminatory power increased with higher odor concentrations over a wide dynamic range, but decreased at the highest concentration. These results show the complexity and diversity of odor information processing mechanisms across olfactory glomeruli in the fly Antennal Lobe.

  • role of histamine as a putative inhibitory transmitter in the honeybee Antennal Lobe
    Frontiers in Zoology, 2006
    Co-Authors: Giovanni C Galizia, Ana F Silbering, Silke Sachse, Philipp Peele, Martin Guhmann
    Abstract:

    Background: Odors are represented by specific spatio-temporal activity patterns in the olfactory bulb of vertebrates and its insect analogue, the Antennal Lobe. In honeybees inhibitory circuits in the AL are involved in the processing of odors to shape afferent odor responses. GABA is known as an inhibitory transmitter in the Antennal Lobe, but not all interneurons are GABAergic. Therefore we sought to analyze the functional role of the inhibitory transmitter histamine for the processing of odors in the honeybee AL. Results: We optically recorded the representation of odors before, during and after histamine application at the input level (estimated from a compound signal), and at the output level (by selectively measuring the projection neurons). For both, histamine led to a strong and reversible reduction of odor-evoked responses. Conclusion: We propose that histamine, in addition to GABA, acts as an inhibitory transmitter in the honeybee AL and is therefore likely to play a role in odor processing.

Bill S Hansson - One of the best experts on this subject based on the ideXlab platform.

  • temporal features of spike trains in the moth Antennal Lobe revealed by a comparative time frequency analysis
    PLOS ONE, 2014
    Co-Authors: Alberto Capurro, Bill S Hansson, Linda S Kuebler, Zsolt Karpati, Hong Lei, Tim Pearce, Fabiano Baroni, Teun Dekker, Shannon B Olsson
    Abstract:

    The discrimination of complex sensory stimuli in a noisy environment is an immense computational task. Sensory systems often encode stimulus features in a spatiotemporal fashion through the complex firing patterns of individual neurons. To identify these temporal features, we have developed an analysis that allows the comparison of statistically significant features of spike trains localized over multiple scales of time-frequency resolution. Our approach provides an original way to utilize the discrete wavelet transform to process instantaneous rate functions derived from spike trains, and select relevant wavelet coefficients through statistical analysis. Our method uncovered localized features within olfactory projection neuron (PN) responses in the moth Antennal Lobe coding for the presence of an odor mixture and the concentration of single component odorants, but not for compound identities. We found that odor mixtures evoked earlier responses in biphasic response type PNs compared to single components, which led to differences in the instantaneous firing rate functions with their signal power spread across multiple frequency bands (ranging from 0 to 45.71 Hz) during a time window immediately preceding behavioral response latencies observed in insects. Odor concentrations were coded in excited response type PNs both in low frequency band differences (2.86 to 5.71 Hz) during the stimulus and in the odor trace after stimulus offset in low (0 to 2.86 Hz) and high (22.86 to 45.71 Hz) frequency bands. These high frequency differences in both types of PNs could have particular relevance for recruiting cellular activity in higher brain centers such as mushroom body Kenyon cells. In contrast, neurons in the specialized pheromone-responsive area of the moth Antennal Lobe exhibited few stimulus-dependent differences in temporal response features. These results provide interesting insights on early insect olfactory processing and introduce a novel comparative approach for spike train analysis applicable to a variety of neuronal data sets.

  • the Antennal Lobe of libellula depressa odonata libellulidae
    Zoology, 2013
    Co-Authors: Manuela Rebora, Alessandro Dellotto, Elda Gaino, Silvana Piersanti, Jurgen Rybak, Bill S Hansson
    Abstract:

    Here we describe the Antennal Lobe of Libellula depressa (Odonata, Libellulidae), identified on the basis of the projections of the afferent sensory neurons stemming from the Antennal flagellum sensilla. Immunohistochemical neuropil staining as well as Antennal backfills revealed sensory neuron terminal arborizations covering a large portion of the Antennal Lobe. No clear glomerular structure was identified, thus suggesting an aglomerular Antennal Lobe condition as previously reported in Palaeoptera. The terminal arbors of backfilled sensory neurons do, however, form spherical knots, probably representing the connections between the few afferent neurons and the Antennal Lobe interneurons. The reconstruction revealed that the proximal part of the Antennal nerve is divided into two branches that innervate two spatially separated areas of the Antennal Lobe, an anterioventral Lobe and a larger posteriodorsal Lobe. Our data are consistent with the hypothesis that one tract of the Antennal nerve of L. depressa contains olfactory sensory neurons projecting into one of the subLobes, while the other tract contains thermo-hygroreceptive neurons projecting into the other subLobe.

  • Antennal Lobe processing correlates to moth olfactory behavior
    The Journal of Neuroscience, 2012
    Co-Authors: Linda S Kuebler, Bill S Hansson, Marco Schubert, Zsolt Karpati, Shannon B Olsson
    Abstract:

    Animals typically perceive their olfactory environment as a complex blend of natural odor cues. In insects, the initial processing of odors occurs in the Antennal Lobe (AL). Afferent peripheral input from olfactory sensory neurons (OSNs) is modified via mostly inhibitory local interneurons (LNs) and transferred by projection neurons (PNs) to higher brain centers. Here we performed optophysiological studies in the AL of the moth, Manduca sexta, and recorded odor-evoked calcium changes in response to Antennal stimulation with five monomolecular host volatiles and their artificial mixture. In a double staining approach, we simultaneously measured OSN network input in concert with PN output across the glomerular array. By comparing odor-evoked activity patterns and response intensities between the two processing levels, we show that host mixtures could generally be predicted from the linear summation of their components at the input of the AL, but output neurons established a unique, nonlinear spatial pattern separate from individual component identities. We then assessed whether particularly high levels of signal modulation correspond to behavioral relevance. One of our mixture components, phenyl acetaldehyde, evoked significant levels of nonlinear input-output modulation in observed spatiotemporal activation patterns that were unique from the other individual odorants tested. This compound also accelerated behavioral activity in subsequent wind tunnel tests, whereas another compound that did not exhibit high levels of modulation also did not affect behavior. These results suggest that the high degree of input-output modulation exhibited by the AL for specific odors can correlate to behavioral output.

  • neuronal processing of complex mixtures establishes a unique odor representation in the moth Antennal Lobe
    Frontiers in Neural Circuits, 2011
    Co-Authors: Linda S Kuebler, Shannon B Olsson, Richard Weniger, Bill S Hansson
    Abstract:

    Animals typically perceive natural odor cues in their olfactory environment as a complex mixture of chemically diverse components. In insects, the initial representation of an odor mixture occurs in the first olfactory center of the brain, the Antennal Lobe (AL). The contribution of single neurons to the processing of complex mixtures in insects, and in particular moths, is still largely unknown. Using a novel multicomponent stimulus system to equilibrate component and mixture concentrations according to vapor pressure, we performed intracellular recordings of projection and interneurons in an attempt to quantitatively characterize mixture representation and integration properties by single AL neurons in the moth. We found that the fine spatiotemporal representation of 2-7 component mixtures among single neurons in the AL revealed a highly combinatorial, non-linear process for coding host mixtures presumably shaped by the Antennal Lobe network: 82% of mixture responding projection neurons (PNs) and local interneurons (LNs) showed non-linear spike frequencies in response to a defined host odor mixture, exhibiting an array of interactions including suppression, hypoadditivity, and synergism. Our results indicate that odor mixtures are represented by each cell as a unique combinatorial representation and there is no general rule by which the network computes the mixture in comparison to single components. On the single neuron level, we show that those differences manifest in a variety of parameters, including the spatial location, frequency, latency, and temporal pattern of the response kinetics.

  • the Antennal Lobe of the african malaria mosquito anopheles gambiae innervation and three dimensional reconstruction
    Arthropod Structure & Development, 2007
    Co-Authors: Majid Ghaninia, Bill S Hansson, Rickard Ignell
    Abstract:

    Antibody labelling and subsequent three-dimensional reconstructions of the primary olfactory centres, the Antennal Lobes, of male and female African malaria mosquitoes, Anopheles gambiae, revealed 61 and 60 glomerular neuropils respectively. In addition to the small difference in number of glomeruli, sexual dimorphism was observed in both the size of the Antennal Lobe and of individual glomeruli. Furthermore, sexual specificity was observed within the array. Anterograde staining of afferents from peripheral olfactory organs support the reconstruction of the glomerular array. Although anterograde stainings support an organotopic organization of the Antennal Lobe, convergence of afferents originating from different organs into single glomeruli is observed. This finding, in both A. gambiae and A. aegypti, may shed new light upon the development and function of the olfactory system.

Conor J Mcmeniman - One of the best experts on this subject based on the ideXlab platform.

  • an updated Antennal Lobe atlas for the yellow fever mosquito aedes aegypti
    PLOS Neglected Tropical Diseases, 2020
    Co-Authors: Shruti Shankar, Conor J Mcmeniman
    Abstract:

    The yellow fever mosquito Aedes aegypti is a prolific vector of arboviral and filarial diseases that largely relies on its sense of smell to find humans. To facilitate in-depth analysis of the neural circuitry underlying Ae. aegypti olfactory-driven behaviors, we generated an updated in vitro atlas for the Antennal Lobe olfactory brain region of this disease vector using two independent neuronal staining methods. We performed morphological reconstructions with replicate fixed, dissected and stained brain samples from adult male and female Ae. aegypti of the LVPib12 genome reference strain and determined that the Antennal Lobe in both sexes is comprised of approximately 80 discrete glomeruli. Guided by landmark features in the Antennal Lobe, we found 63 of these glomeruli are stereotypically located in spatially invariant positions within these in vitro preparations. A posteriorly positioned, mediodorsal glomerulus denoted MD1 was identified as the largest spatially invariant glomerulus in the Antennal Lobe. Spatial organization of glomeruli in a recently field-derived strain of Ae. aegypti from Puerto Rico was conserved, despite differences in Antennal Lobe shape relative to the inbred LVPib12 strain. This model in vitro atlas will serve as a useful community resource to improve Antennal Lobe annotation and anatomically map projection patterns of neurons expressing target genes in this olfactory center. It will also facilitate the development of chemotopic maps of odor representation in the mosquito Antennal Lobe to decode the molecular and cellular basis of Ae. aegypti attraction to human scent and other chemosensory cues.

  • an updated Antennal Lobe atlas for the yellow fever mosquito aedes aegypti
    bioRxiv, 2019
    Co-Authors: Shruti Shankar, Conor J Mcmeniman
    Abstract:

    The yellow fever mosquito Aedes aegypti is a prolific vector of arboviral and filarial diseases that largely relies on its sense of smell to find humans. To facilitate in-depth analysis of the neural circuitry underlying Ae. aegypti olfactory-driven behaviors, we generated an updated in vitro atlas for the Antennal Lobe olfactory brain region of this disease vector using two independent neuronal staining methods. We performed morphological reconstructions with replicate fixed, dissected and stained brain samples from adult male and female Ae. aegypti of the LVPib12 genome reference strain and determined that the Antennal Lobe in both sexes is comprised of approximately 80 discrete glomeruli. Guided by landmark features in the Antennal Lobe, we found 63 of these glomeruli are stereotypically located in spatially invariant positions within these in vitro preparations. A posteriorly positioned, mediodorsal glomerulus denoted MD1 was identified as the largest spatially invariant glomerulus in the Antennal Lobe. Spatial organization of glomeruli in a recently field-derived strain of Ae. aegypti from Puerto Rico was conserved, despite differences in Antennal Lobe shape relative to the inbred LVPib12 strain. This model in vitro atlas will serve as a useful community guide and resource to improve Antennal Lobe annotation and anatomically map projection patterns of neurons expressing target genes in this olfactory center. It will also facilitate the development of chemotopic maps of odor representation in the mosquito Antennal Lobe to decode the molecular and cellular basis of Ae. aegypti attraction to human scent and other chemosensory cues.

Sylvia Anton - One of the best experts on this subject based on the ideXlab platform.

  • three dimensional Antennal Lobe atlas of male and female moths Lobesia botrana lepidoptera tortricidae and glomerular representation of plant volatiles in females
    The Journal of Experimental Biology, 2005
    Co-Authors: Ingwild Masanteroca, Christophe Gadenne, Sylvia Anton
    Abstract:

    SUMMARY Spatiotemporal odour coding is thought to be linked closely with the specific glomerular anatomy of the primary olfactory centre. In most insects the number of the glomeruli within the Antennal Lobe is limited to fewer than 100, allowing their individual identification. In the grapevine moth, Lobesia botrana , a map of the Antennal Lobe glomeruli was reconstructed three-dimensionally, by comparing three different brains in males and females. The map of the Antennal Lobe of females served then as a basis to identify glomeruli containing dendritic arborisations of 14 physiologically characterised projection neurons. Projection neurons responding to the same plant compound did not always arborise in the same glomerulus and some neurons arborising in the same glomerulus responded to different compounds. Different zones of target glomeruli were, however, identified when pooling all neurons responding to one of two different compounds respectively (α-farnesene and nonatriene). All identified glomeruli of specifically responding projection neurons were situated close to the anterior surface of the Antennal Lobe. One broadly responding projection neuron arborised in a more posteriorly situated glomerulus. A local interneuron responding to only one compound was arborising densely in a neighbouring glomerulus and had sparse branches in all other glomeruli. These results are discussed with respect to plant odour processing and structure-function relations in Antennal Lobe neurons. The 3D AL atlas will, in the future, also be used to obtain a better understanding of coding mechanisms of grapevine odours in this pest insect.

  • three dimensional Antennal Lobe atlas of the male moth agrotis ipsilon a tool to study structure function correlation
    The Journal of Comparative Neurology, 2004
    Co-Authors: Birgit Greiner, Christophe Gadenne, Sylvia Anton
    Abstract:

    The glomerular structure of the primary olfactory neuropil has long been thought to play an important role in odour coding. In insects, the number of glomeruli in the Antennal Lobe is limited in most species to fewer than 100 compared with more than 1,000 in vertebrates, making it possible to identify individual glomeruli. A complete three-dimensional atlas of the glomeruli within the Antennal Lobe of the male noctuid moth Agrotis ipsilon was constructed. All 66 glomeruli were singly identifiable in both Antennal Lobes of the three brains investigated. Further, six Antennal Lobes containing intracellularly stained projection neurones were reconstructed. By using the atlas, the respective target glomerulus of each projection neurone could be identified. The importance of the glomerular atlas as a tool to study central olfactory processing and its plasticity is discussed.

  • the Antennal Lobe of orthoptera anatomy and evolution
    Brain Behavior and Evolution, 2001
    Co-Authors: Rickard Ignell, Sylvia Anton, Bill S Hansson
    Abstract:

    The first odor-processing neuropils of insects comprise glomeruli, islets of neuropil, that are supplied by olfactory receptor neurons and give rise to efferent axons to higher brain centers. Glomeruli size and organization varies in a taxon-specific manner across the Insecta, suggesting possible correlates between their organization and chemosensory behaviors in different insect groups. Comparative studies of Antennal Lobe glomeruli within the Orthoptera have been used to infer how the various taxon-specific arrangements of odorant-processing structures (glomeruli) might have evolved. The cellular arrangements in glomeruli have been surveyed using anterograde filling and Golgi impregnation of Antennal receptor neurons projecting to the Antennal Lobe in Stenopelmatidae, Tettigoniidae, Gryllidae, Tetrigidae and Acrididae. These taxa, which represent the two sub-orders of Orthoptera, reveal a high correlation between the neural architecture of the glomeruli and structures within the glomeruli. Using a recent molecular phylogeny of the Orthoptera we have mapped the occurrence of glomerular characteristics to infer the evolution of Antennal Lobe structures in orthopterans. The functional implications of these results are discussed.

Hanna Mustaparta - One of the best experts on this subject based on the ideXlab platform.

  • anatomical organization of Antennal Lobe projection neurons in the moth heliothis virescens
    The Journal of Comparative Neurology, 2007
    Co-Authors: R O Helge, Dirk Muller, Hanna Mustaparta
    Abstract:

    A prerequisite for understanding how odor information is coded in the central nervous system is to know the morphology and spatial relationship of the principal neurons forming the olfactory pathways. The present account provides an anatomical description of the morphology of the neuronal connections between the Antennal Lobe and the protocerebrum in the moth Heliothis virescens, a species used for studies of olfactory processing and learning. Intracellular labeling and Antennal Lobe focal injections with dextran fluorescent markers were combined with neuropil immunostaining and three-dimensional reconstructions. The experiments revealed four antennocerebral tracts, the inner, middle, outer, and dorsomedial, and eight morphological types of projection neurons in addition to a neuron with an unpaired median soma in the subesophageal ganglion. Multiglomerular projection neurons, present in all but the dorsomedial antennocerebral tract, project in several olfactory foci of the protocerebral neuropil. With few exceptions, these neurons do not innervate the calyces of the mushroom body. Uniglomerular projection neurons appear most numerous in the inner antennocerebral tract but are also present in the outer and dorsomedial tracts. These neurons always ramify in the calyces of the mushroom body and in the lateral horn. The projection areas of the neurons following different tracts are largely separated in the secondary olfactory centers. This is most evident in the lateral horn, whereas, in the calyces, the axonal ramifications are more intermingled. The mushroom body architecture, revealed by neuropil immunolabeling, showed striking similarities to that of other lepidopteran species as well as insects of other taxa. J. Comp. Neurol. 500:658–675, 2007. © 2006 Wiley-Liss, Inc.

  • anatomical organization of Antennal Lobe projection neurons in the moth heliothis virescens
    The Journal of Comparative Neurology, 2007
    Co-Authors: Dirk Muller, Hanna Mustaparta
    Abstract:

    A prerequisite for understanding how odor information is coded in the central nervous system is to know the morphology and spatial relationship of the principal neurons forming the olfactory pathways. The present account provides an anatomical description of the morphology of the neuronal connections between the Antennal Lobe and the protocerebrum in the moth Heliothis virescens, a species used for studies of olfactory processing and learning. Intracellular labeling and Antennal Lobe focal injections with dextran fluorescent markers were combined with neuropil immunostaining and three-dimensional reconstructions. The experiments revealed four antennocerebral tracts, the inner, middle, outer, and dorsomedial, and eight morphological types of projection neurons in addition to a neuron with an unpaired median soma in the subesophageal ganglion. Multiglomerular projection neurons, present in all but the dorsomedial antennocerebral tract, project in several olfactory foci of the protocerebral neuropil. With few exceptions, these neurons do not innervate the calyces of the mushroom body. Uniglomerular projection neurons appear most numerous in the inner antennocerebral tract but are also present in the outer and dorsomedial tracts. These neurons always ramify in the calyces of the mushroom body and in the lateral horn. The projection areas of the neurons following different tracts are largely separated in the secondary olfactory centers. This is most evident in the lateral horn, whereas, in the calyces, the axonal ramifications are more intermingled. The mushroom body architecture, revealed by neuropil immunolabeling, showed striking similarities to that of other lepidopteran species as well as insects of other taxa.

  • digital atlases of the Antennal Lobe in two species of tobacco budworm moths the oriental helicoverpa assulta male and the american heliothis virescens male and female
    The Journal of Comparative Neurology, 2002
    Co-Authors: Bente G Berg, Giovanni C Galizia, Robert Brandt, Hanna Mustaparta
    Abstract:

    The Antennal Lobe of the moth brain is the primary olfactory center processing information about pheromones and plant odors. We present here a digital atlas of the glomerular Antennal Lobe structures in the male of Helicoverpa assulta and the male and female of Heliothis virescens, based on synaptic antibody staining combined with confocal microscopy. The numbers of the glomeruli in the three specimens were similar, 65, 66, and 62, respectively. Whereas the male Antennal Lobe has a macroglomerular complex consisting of three and four units in the two species, the female Lobe has two enlarged glomeruli at a corresponding position, near the entrance of the Antennal nerve. Another large glomerulus, showing homology in the three specimens, is ventrally located. The small size of the heliothine moths is advantageous for confocal microscopy because the entire brain can be visualized as a single image stack. The maps are freely accessible on the internet, and the digital form of the data allows each atlas to be rotated and sectioned at any angle, providing for the identification of glomeruli in different preparations. J. Comp. Neurol.

  • calcium responses to pheromones and plant odours in the Antennal Lobe of the male and female moth heliothis virescens
    Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology, 2000
    Co-Authors: Cosmas Giovanni Galizia, Silke Sachse, Hanna Mustaparta
    Abstract:

    In male moths, the primary olfactory integration centre, the Antennal Lobe, consists of two systems. The macroglomerular complex processes pheromone information, while the ordinary glomeruli process plant odour information. Females lack a macroglomerular complex. We measured the spatial representation of odours using in-vivo optical recording. We found that: (1) pheromone substances elicited activity exclusively in the MGC. No response was found in female Antennal Lobes. (2) Plant odours elicited combinatorial activity patterns in the ordinary glomeruli in both males and females. No response was found in the MGC of male moths. (3) A clean air puff often led to activity, in both males and females, suggesting that mechano-sensory information is also processed in the Antennal Lobe. (4) With an inter-stimulus interval of 5 or 10 s, strongly activated glomeruli were able to follow the temporal structure of the stimulus, while others lost their phase-locking. Some glomeruli showed "off" responses. These properties were odour dependent. This confirms and extends previous studies, showing the functional significance of the two subsystems for processing olfactory information. Pheromones are coded in a combinatorial manner within the macroglomerular complex, with each glomerulus corresponding to one information channel. Plant odours are coded in an across-glomeruli code in the ordinary glomeruli.