Marco Paoli | Centre National de la Recherche Scientifique / French National Centre for Scientific Research (original) (raw)
Papers by Marco Paoli
Toxicon, Jun 1, 2013
again under the supervision of Prof. Habermann. In 1981 he spent 12 months at the National Instit... more again under the supervision of Prof. Habermann. In 1981 he spent 12 months at the National Institutes of Health, Bethesda, MD, and was trained in electrophysiology. Returning to the laboratory of Prof. Habermann, he studied the mode of action of tetanus toxin, first by making antibodies and then by developing electrophysiological methods. He received his Habilitation in 1986. Since 1986, he has been Professor and Vice-Chairman of Toxicology at the Medical School of Hannover, Germany. He directs a research group working on the binding characteristics of botulinum toxins. On September 30, 2011, he will begin his retirement. He has more than 80 publications in the field and is an inventor on four issued or pending patents. He wrote several reviews and chapters in textbooks of pharmacology and toxicology. Since 2008 and currently, he is Chief Executive Officer of Toxogen GmbH, a spin-off of the Hannover Medical School. The company works on methods for the detection and quantification of botulinum toxins, has developed a test for the quantification of anti-botulinum-toxin antibodies in human sera, and performs research on protein-based peripheral muscle relaxants.
Insects
Odorant processing presents multiple parallels across animal species, and insects became relevant... more Odorant processing presents multiple parallels across animal species, and insects became relevant models for the study of olfactory coding because of the tractability of the underlying neural circuits. Within the insect brain, odorants are received by olfactory sensory neurons and processed by the antennal lobe network. Such a network comprises multiple nodes, named glomeruli, that receive sensory information and are interconnected by local interneurons participating in shaping the neural representation of an odorant. The study of functional connectivity between the nodes of a sensory network in vivo is a challenging task that requires simultaneous recording from multiple nodes at high temporal resolutions. Here, we followed the calcium dynamics of antennal lobe glomeruli and applied Granger causality analysis to assess the functional connectivity among network nodes in the presence and absence of an odorous stimulus. This approach revealed the existence of causal connectivity links...
Odorant processing presents multiple parallels across animal species, and insects became relevant... more Odorant processing presents multiple parallels across animal species, and insects became relevant models for the study of olfactory coding because of the tractability of the underlying neural circuits. Within the insect brain, odorants are received by olfactory sensory neurons and processed by the antennal lobe network. Such a network comprises multiple nodes, named glomeruli, that receive sensory information and are interconnected by local interneurons participating in shaping the neural representation of an odorant. The study of functional connectivity between the nodes of a sensory networkin vivois a challenging task that requires simultaneous recording from multiple nodes at high temporal resolutions. Here, we used fast two-photon microscopy to follow the calcium dynamics of antennal lobe glomeruli and applied Granger causality analysis to assess the functional directed connectivity among network nodes during and after olfactory stimulation. Our findings show that there is a sig...
In this study we investigated the olfactory coding mechanisms of the honey bee Apis mellifera by ... more In this study we investigated the olfactory coding mechanisms of the honey bee Apis mellifera by analyzing the dynamics of the antennal lobe glomeruli in response to the presentation of different olfactory stimuli. We produced functional and effective connectivity response networks for eight different stimuli and three specific temporal windows (ON, early-OFF, and OFF). The functional response graphs were produced from the zero-delay cross-correlation between the different glomerular signals, while the effective response graphs were based on the Granger causality of the same time series. When comparing the two measures, despite the fundamental differences in the concepts such as the presence of information on the directionality in Granger causality, we observed consistency between the correlation and causality results which show peculiar activation patterns related to the specific stimulus, specifically in the slow components of the signals. This suggests the possibility of integrating functional and effective connectivity to reduce false positive reports of statistically dependent patterns not resulting from physiological phenomena.
iScience, 2021
Cockroaches invert their innate preference to vanillin when in a group The inversion occurs also ... more Cockroaches invert their innate preference to vanillin when in a group The inversion occurs also when the social context is replaced with a colony odor Vanillin-related antennal lobe activity is reduced in presence of a colony odor This could serve as a mechanism to avoid recently exploited resources
Journal of Experimental Biology, 2020
The general architecture of the olfactory system is highly conserved from insects to humans, but ... more The general architecture of the olfactory system is highly conserved from insects to humans, but neuroanatomical and physiological differences can be observed across species. The American cockroach, inhabiting dark shelters with a rather stable olfactory landscape, is equipped with long antennae used for sampling the surrounding air-space for orientation and navigation. The antennae's exceptional length provides a wide spatial working range for odour detection; however, it is still largely unknown whether and how this is also used for mapping the structure of the olfactory environment. By selective labelling antennal lobe projection neurons with a calcium sensitive dye, we investigated the logic of olfactory coding in this hemimetabolous insect. We show that odour responses are stimulus-specific and concentration-dependent, and that structurally related odorants evoke physiologically similar responses. By using spatially confined stimuli, we show that proximal stimulations induc...
ABSTRACTDrosophila suzukiiis an invasive agricultural pest species that lays eggs in fruit during... more ABSTRACTDrosophila suzukiiis an invasive agricultural pest species that lays eggs in fruit during ripening, while most closely relatedDrosophilaspecies use rotten matter as oviposition substrates. This behaviour is allowed by an enlarged and serrated ovipositor that can pierce intact fruit skin.D. suzukiicombines multiple sensory systems (mechanosensation, olfaction, and taste) to select oviposition sites. Here, we test the hypothesis that theD. suzukiiovipositor is involved in these sensory modalities. We first investigate the ovipositor gene expression using a comparative framework of fourDrosophilaspecies with gradual changes in ovipositor morphology to identify evolutionary adaptations specific toD. suzukii. Results show transcription of chemoreceptors and mechanoreceptors in the four species, with a common core of sensory receptors expressed in all of them. Then, we demonstrate that sensory structures present in the distal tip of theD. suzukiiovipositor are mechanosensory-like ...
Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2017
Odour reception takes place on the olfactory receptor neuron membrane, where molecular receptors ... more Odour reception takes place on the olfactory receptor neuron membrane, where molecular receptors interact with volatile odorant molecules. This interaction is classically thought to rely on chemical and structural features of the odorant, e.g. size, shape, functional groups. However, this model does not allow formulating a correct prediction for the smell of an odorant, suggesting that other molecular properties may play a role in the odour transduction process. An alternative model of olfaction maintains that odorant receptors can probe not only the structural and chemical features, but also the molecular vibration spectrum of the odorants. This constitutes the so-called vibration model of olfaction. According to this model, two isotopomers of the same molecule, i.e. two forms of the same molecule, one unaltered and one in which one or more hydrogen atoms are substituted with deuterium – which are therefore structurally and chemically identical, but with different molecular vibrati...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 24, 2018
Odorants are coded in the primary olfactory processing centers by spatially and temporally distri... more Odorants are coded in the primary olfactory processing centers by spatially and temporally distributed patterns of glomerular activity. Whereas the spatial distribution of odorant-induced responses is known to be conserved across individuals, the universality of its temporal structure is still debated. Via fast two-photon calcium imaging, we analyzed the early phase of neuronal responses in the form of the activity onset latencies in the antennal lobe projection neurons of honeybee foragers. We show that each odorant evokes a stimulus-specific response latency pattern across the glomerular coding space. Moreover, we investigate these early response features for the first time across animals, revealing that the order of glomerular firing onsets is conserved across individuals and allows them to reliably predict odorant identity, but not concentration. These results suggest that the neuronal response latencies provide the first available code for fast odor identification. Here, we stu...
Current biology : CB, Jan 19, 2018
Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms th... more Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms that allow an animal to encode the spatial structure of an odorous environment remain unclear. To acquire information about the spatial distribution of an odorant, animals may rely on bilateral olfactory organs and compare side differences of odor intensity and timing [1-6] or may perform spatial and temporal signal integration of subsequent samplings [7]. The American cockroach can efficiently locate a source of sex pheromone even after the removal of one antenna, suggesting that bilateral comparison is not a prerequisite for odor localization in this species [8, 9]. Cognate olfactory sensory neurons (OSNs) originating from different locations on the flagellum, but bearing the same olfactory receptor, converge onto the same glomerulus within the antennal lobe, which is thought to result in a loss of spatial information. Here, we identified 12 types of pheromone-responsive projection neuro...
eneuro, 2017
Several studies have attempted to test the vibrational hypothesis of odorant receptor activation ... more Several studies have attempted to test the vibrational hypothesis of odorant receptor activation in behavioral and physiological studies using deuterated compounds as odorants. The results have been mixed. Here, we attempted to test how deuterated compounds activate odorant receptors using calcium imaging of the fruit fly antennal lobe. We found specific activation of one area of the antennal lobe corresponding to inputs from a specific receptor. However, upon more detailed analysis, we discovered that an impurity of 0.0006% ethyl acetate in a chemical sample of benzaldehyde-d5was entirely responsible for a sizable odorant-evoked response inDrosophila melanogasterolfactory receptor cells expressing dOr42b. Without gas chromatographic purification within the experimental setup, this impurity would have created a difference in the responses of deuterated and nondeuterated benzaldehyde, suggesting that dOr42b be a vibration sensitive receptor, which we show here not to be the case. Our...
European Journal of Neuroscience, 2016
Antennal lobes constitute the first neurophils in the insect brain involved in coding and process... more Antennal lobes constitute the first neurophils in the insect brain involved in coding and processing of olfactory information. With their stereotyped functional and anatomical organization, they provide an accessible model with which to investigate information processing of an external stimulus in a neural network in vivo. Here, by combining functional calcium imaging with time-frequency analysis, we have been able to monitor the oscillatory components of neural activity upon olfactory stimulation. The aim of the present study is to investigate the presence of stimulus-induced oscillatory patterns in the honeybee antennal lobe, and to analyse the distribution of those patterns across the antennal lobe glomeruli. Fast two-photon calcium imaging reveals the presence of low-frequency oscillations, the intensity of which is perturbed by an incoming stimulus. Moreover, analysis of the spatial arrangement of this activity indicates that it is not homogeneous throughout the antennal lobe. On the contrary, each glomerulus displays an odorant-specific time-frequency profile, and acts as a functional unit of the oscillatory activity. The presented approach allows simultaneous recording of complex activity patterns across several nodes of the antennal lobe, providing the means to better understand the network dynamics regulating olfactory coding and leading to perception.
Scientific Reports, 2016
The shape recognition model of olfaction maintains that odorant reception probes physicochemical ... more The shape recognition model of olfaction maintains that odorant reception probes physicochemical properties such as size, shape, electric charge and hydrophobicity of the ligand. Recently, insects were shown to distinguish common from deuterated isotopomers of the same odorant, suggesting the involvement of other molecular properties to odorant reception. Via two-photon functional microscopy we investigated how common and deuterated isoforms of natural odorants are coded within the honeybee brain. Our results provide evidence that (i) different isotopomers generate different neuronal activation maps, (ii) isotopomer sensitivity is a general mechanism common to multiple odorant receptors and (iii) isotopomer specificity is highly consistent across individuals. This indicates that honeybee’s olfactory system discriminates between isotopomers of the same odorant, suggesting that other features, such as molecular vibrations, may contribute to odour signal transduction.
Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis melli... more Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis mellifera, is a well-established model for studying the anatomical bases of odor coding and olfactory memory. The bee primary olfactory centers, the antennal lobes (ALs), are organized in a fixed arrangement of spheroidal neuropil units, the glomeruli. These structures receive inputs from the bee olfactory receptor neurons (ORNs), are modulated by local interneurons (LINs), and send outputs to higher brain centers through the projection neurons (PNs). The spatio-temporal pattern of activation of the glomeruli is odor-specific, thus, imaging of intracellular calcium of the PNs may provide maps of odor representation. Such maps have been demonstrated to vary upon olfactory conditioning (i.e. through enhancement of the discrimination of a rewarded odor against an unrewarded one), but the underlying mechanisms for this plasticity are not known. The aim of this study is to investigate plastic changes following odor conditioning and, in particular, possible variations in number and morphology of the synapses involved in the ALs circuitry.
Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis melli... more Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis mellifera, is a well-established model for studying the anatomical bases of odor coding and olfactory memory. The bee primary olfactory centers, the antennal lobes (ALs), are organized in a fixed arrangement of spheroidal neuropil units, the glomeruli. These structures receive inputs from the bee olfactory receptor neurons (ORNs), are modulated by local interneurons (LINs), and send outputs to higher brain centers through the projection neurons (PNs). The spatio-temporal pattern of activation of the glomeruli is odor-specific, thus, imaging of intracellular calcium of the PNs may provide maps of odor representation. Such maps have been demonstrated to vary upon olfactory conditioning (i.e. through enhancement of the discrimination of a rewarded odor against an unrewarded one), but the underlying mechanisms for this plasticity are not known. The aim of this study is to investigate plastic changes following odor conditioning and, in particular, possible variations in number and morphology of the synapses involved in the ALs circuitry.
Journal of Insect Physiology
Methods in molecular biology (Clifton, N.J.), 2018
This chapter describes how to apply two-photon neuroimaging to study the insect olfactory system ... more This chapter describes how to apply two-photon neuroimaging to study the insect olfactory system in vivo. It provides a complete protocol for insect brain functional imaging, with some additional remarks on the acquisition of morphological information from the living brain. We discuss the most important choices to make when buying or building a two-photon laser-scanning microscope. We illustrate different possibilities of animal preparation and brain tissue labeling for in vivo imaging. Finally, we give an overview of the main methods of image data processing and analysis, followed by a short description of pioneering applications of this imaging modality.
Toxicon, Jun 1, 2013
again under the supervision of Prof. Habermann. In 1981 he spent 12 months at the National Instit... more again under the supervision of Prof. Habermann. In 1981 he spent 12 months at the National Institutes of Health, Bethesda, MD, and was trained in electrophysiology. Returning to the laboratory of Prof. Habermann, he studied the mode of action of tetanus toxin, first by making antibodies and then by developing electrophysiological methods. He received his Habilitation in 1986. Since 1986, he has been Professor and Vice-Chairman of Toxicology at the Medical School of Hannover, Germany. He directs a research group working on the binding characteristics of botulinum toxins. On September 30, 2011, he will begin his retirement. He has more than 80 publications in the field and is an inventor on four issued or pending patents. He wrote several reviews and chapters in textbooks of pharmacology and toxicology. Since 2008 and currently, he is Chief Executive Officer of Toxogen GmbH, a spin-off of the Hannover Medical School. The company works on methods for the detection and quantification of botulinum toxins, has developed a test for the quantification of anti-botulinum-toxin antibodies in human sera, and performs research on protein-based peripheral muscle relaxants.
Insects
Odorant processing presents multiple parallels across animal species, and insects became relevant... more Odorant processing presents multiple parallels across animal species, and insects became relevant models for the study of olfactory coding because of the tractability of the underlying neural circuits. Within the insect brain, odorants are received by olfactory sensory neurons and processed by the antennal lobe network. Such a network comprises multiple nodes, named glomeruli, that receive sensory information and are interconnected by local interneurons participating in shaping the neural representation of an odorant. The study of functional connectivity between the nodes of a sensory network in vivo is a challenging task that requires simultaneous recording from multiple nodes at high temporal resolutions. Here, we followed the calcium dynamics of antennal lobe glomeruli and applied Granger causality analysis to assess the functional connectivity among network nodes in the presence and absence of an odorous stimulus. This approach revealed the existence of causal connectivity links...
Odorant processing presents multiple parallels across animal species, and insects became relevant... more Odorant processing presents multiple parallels across animal species, and insects became relevant models for the study of olfactory coding because of the tractability of the underlying neural circuits. Within the insect brain, odorants are received by olfactory sensory neurons and processed by the antennal lobe network. Such a network comprises multiple nodes, named glomeruli, that receive sensory information and are interconnected by local interneurons participating in shaping the neural representation of an odorant. The study of functional connectivity between the nodes of a sensory networkin vivois a challenging task that requires simultaneous recording from multiple nodes at high temporal resolutions. Here, we used fast two-photon microscopy to follow the calcium dynamics of antennal lobe glomeruli and applied Granger causality analysis to assess the functional directed connectivity among network nodes during and after olfactory stimulation. Our findings show that there is a sig...
In this study we investigated the olfactory coding mechanisms of the honey bee Apis mellifera by ... more In this study we investigated the olfactory coding mechanisms of the honey bee Apis mellifera by analyzing the dynamics of the antennal lobe glomeruli in response to the presentation of different olfactory stimuli. We produced functional and effective connectivity response networks for eight different stimuli and three specific temporal windows (ON, early-OFF, and OFF). The functional response graphs were produced from the zero-delay cross-correlation between the different glomerular signals, while the effective response graphs were based on the Granger causality of the same time series. When comparing the two measures, despite the fundamental differences in the concepts such as the presence of information on the directionality in Granger causality, we observed consistency between the correlation and causality results which show peculiar activation patterns related to the specific stimulus, specifically in the slow components of the signals. This suggests the possibility of integrating functional and effective connectivity to reduce false positive reports of statistically dependent patterns not resulting from physiological phenomena.
iScience, 2021
Cockroaches invert their innate preference to vanillin when in a group The inversion occurs also ... more Cockroaches invert their innate preference to vanillin when in a group The inversion occurs also when the social context is replaced with a colony odor Vanillin-related antennal lobe activity is reduced in presence of a colony odor This could serve as a mechanism to avoid recently exploited resources
Journal of Experimental Biology, 2020
The general architecture of the olfactory system is highly conserved from insects to humans, but ... more The general architecture of the olfactory system is highly conserved from insects to humans, but neuroanatomical and physiological differences can be observed across species. The American cockroach, inhabiting dark shelters with a rather stable olfactory landscape, is equipped with long antennae used for sampling the surrounding air-space for orientation and navigation. The antennae's exceptional length provides a wide spatial working range for odour detection; however, it is still largely unknown whether and how this is also used for mapping the structure of the olfactory environment. By selective labelling antennal lobe projection neurons with a calcium sensitive dye, we investigated the logic of olfactory coding in this hemimetabolous insect. We show that odour responses are stimulus-specific and concentration-dependent, and that structurally related odorants evoke physiologically similar responses. By using spatially confined stimuli, we show that proximal stimulations induc...
ABSTRACTDrosophila suzukiiis an invasive agricultural pest species that lays eggs in fruit during... more ABSTRACTDrosophila suzukiiis an invasive agricultural pest species that lays eggs in fruit during ripening, while most closely relatedDrosophilaspecies use rotten matter as oviposition substrates. This behaviour is allowed by an enlarged and serrated ovipositor that can pierce intact fruit skin.D. suzukiicombines multiple sensory systems (mechanosensation, olfaction, and taste) to select oviposition sites. Here, we test the hypothesis that theD. suzukiiovipositor is involved in these sensory modalities. We first investigate the ovipositor gene expression using a comparative framework of fourDrosophilaspecies with gradual changes in ovipositor morphology to identify evolutionary adaptations specific toD. suzukii. Results show transcription of chemoreceptors and mechanoreceptors in the four species, with a common core of sensory receptors expressed in all of them. Then, we demonstrate that sensory structures present in the distal tip of theD. suzukiiovipositor are mechanosensory-like ...
Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale, 2017
Odour reception takes place on the olfactory receptor neuron membrane, where molecular receptors ... more Odour reception takes place on the olfactory receptor neuron membrane, where molecular receptors interact with volatile odorant molecules. This interaction is classically thought to rely on chemical and structural features of the odorant, e.g. size, shape, functional groups. However, this model does not allow formulating a correct prediction for the smell of an odorant, suggesting that other molecular properties may play a role in the odour transduction process. An alternative model of olfaction maintains that odorant receptors can probe not only the structural and chemical features, but also the molecular vibration spectrum of the odorants. This constitutes the so-called vibration model of olfaction. According to this model, two isotopomers of the same molecule, i.e. two forms of the same molecule, one unaltered and one in which one or more hydrogen atoms are substituted with deuterium – which are therefore structurally and chemically identical, but with different molecular vibrati...
The Journal of neuroscience : the official journal of the Society for Neuroscience, Jan 24, 2018
Odorants are coded in the primary olfactory processing centers by spatially and temporally distri... more Odorants are coded in the primary olfactory processing centers by spatially and temporally distributed patterns of glomerular activity. Whereas the spatial distribution of odorant-induced responses is known to be conserved across individuals, the universality of its temporal structure is still debated. Via fast two-photon calcium imaging, we analyzed the early phase of neuronal responses in the form of the activity onset latencies in the antennal lobe projection neurons of honeybee foragers. We show that each odorant evokes a stimulus-specific response latency pattern across the glomerular coding space. Moreover, we investigate these early response features for the first time across animals, revealing that the order of glomerular firing onsets is conserved across individuals and allows them to reliably predict odorant identity, but not concentration. These results suggest that the neuronal response latencies provide the first available code for fast odor identification. Here, we stu...
Current biology : CB, Jan 19, 2018
Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms th... more Animals rely on olfaction to navigate through complex olfactory landscapes, but the mechanisms that allow an animal to encode the spatial structure of an odorous environment remain unclear. To acquire information about the spatial distribution of an odorant, animals may rely on bilateral olfactory organs and compare side differences of odor intensity and timing [1-6] or may perform spatial and temporal signal integration of subsequent samplings [7]. The American cockroach can efficiently locate a source of sex pheromone even after the removal of one antenna, suggesting that bilateral comparison is not a prerequisite for odor localization in this species [8, 9]. Cognate olfactory sensory neurons (OSNs) originating from different locations on the flagellum, but bearing the same olfactory receptor, converge onto the same glomerulus within the antennal lobe, which is thought to result in a loss of spatial information. Here, we identified 12 types of pheromone-responsive projection neuro...
eneuro, 2017
Several studies have attempted to test the vibrational hypothesis of odorant receptor activation ... more Several studies have attempted to test the vibrational hypothesis of odorant receptor activation in behavioral and physiological studies using deuterated compounds as odorants. The results have been mixed. Here, we attempted to test how deuterated compounds activate odorant receptors using calcium imaging of the fruit fly antennal lobe. We found specific activation of one area of the antennal lobe corresponding to inputs from a specific receptor. However, upon more detailed analysis, we discovered that an impurity of 0.0006% ethyl acetate in a chemical sample of benzaldehyde-d5was entirely responsible for a sizable odorant-evoked response inDrosophila melanogasterolfactory receptor cells expressing dOr42b. Without gas chromatographic purification within the experimental setup, this impurity would have created a difference in the responses of deuterated and nondeuterated benzaldehyde, suggesting that dOr42b be a vibration sensitive receptor, which we show here not to be the case. Our...
European Journal of Neuroscience, 2016
Antennal lobes constitute the first neurophils in the insect brain involved in coding and process... more Antennal lobes constitute the first neurophils in the insect brain involved in coding and processing of olfactory information. With their stereotyped functional and anatomical organization, they provide an accessible model with which to investigate information processing of an external stimulus in a neural network in vivo. Here, by combining functional calcium imaging with time-frequency analysis, we have been able to monitor the oscillatory components of neural activity upon olfactory stimulation. The aim of the present study is to investigate the presence of stimulus-induced oscillatory patterns in the honeybee antennal lobe, and to analyse the distribution of those patterns across the antennal lobe glomeruli. Fast two-photon calcium imaging reveals the presence of low-frequency oscillations, the intensity of which is perturbed by an incoming stimulus. Moreover, analysis of the spatial arrangement of this activity indicates that it is not homogeneous throughout the antennal lobe. On the contrary, each glomerulus displays an odorant-specific time-frequency profile, and acts as a functional unit of the oscillatory activity. The presented approach allows simultaneous recording of complex activity patterns across several nodes of the antennal lobe, providing the means to better understand the network dynamics regulating olfactory coding and leading to perception.
Scientific Reports, 2016
The shape recognition model of olfaction maintains that odorant reception probes physicochemical ... more The shape recognition model of olfaction maintains that odorant reception probes physicochemical properties such as size, shape, electric charge and hydrophobicity of the ligand. Recently, insects were shown to distinguish common from deuterated isotopomers of the same odorant, suggesting the involvement of other molecular properties to odorant reception. Via two-photon functional microscopy we investigated how common and deuterated isoforms of natural odorants are coded within the honeybee brain. Our results provide evidence that (i) different isotopomers generate different neuronal activation maps, (ii) isotopomer sensitivity is a general mechanism common to multiple odorant receptors and (iii) isotopomer specificity is highly consistent across individuals. This indicates that honeybee’s olfactory system discriminates between isotopomers of the same odorant, suggesting that other features, such as molecular vibrations, may contribute to odour signal transduction.
Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis melli... more Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis mellifera, is a well-established model for studying the anatomical bases of odor coding and olfactory memory. The bee primary olfactory centers, the antennal lobes (ALs), are organized in a fixed arrangement of spheroidal neuropil units, the glomeruli. These structures receive inputs from the bee olfactory receptor neurons (ORNs), are modulated by local interneurons (LINs), and send outputs to higher brain centers through the projection neurons (PNs). The spatio-temporal pattern of activation of the glomeruli is odor-specific, thus, imaging of intracellular calcium of the PNs may provide maps of odor representation. Such maps have been demonstrated to vary upon olfactory conditioning (i.e. through enhancement of the discrimination of a rewarded odor against an unrewarded one), but the underlying mechanisms for this plasticity are not known. The aim of this study is to investigate plastic changes following odor conditioning and, in particular, possible variations in number and morphology of the synapses involved in the ALs circuitry.
Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis melli... more Imaging plasticity in the honeybee antennal lobe The olfactory system of the honeybee, Apis mellifera, is a well-established model for studying the anatomical bases of odor coding and olfactory memory. The bee primary olfactory centers, the antennal lobes (ALs), are organized in a fixed arrangement of spheroidal neuropil units, the glomeruli. These structures receive inputs from the bee olfactory receptor neurons (ORNs), are modulated by local interneurons (LINs), and send outputs to higher brain centers through the projection neurons (PNs). The spatio-temporal pattern of activation of the glomeruli is odor-specific, thus, imaging of intracellular calcium of the PNs may provide maps of odor representation. Such maps have been demonstrated to vary upon olfactory conditioning (i.e. through enhancement of the discrimination of a rewarded odor against an unrewarded one), but the underlying mechanisms for this plasticity are not known. The aim of this study is to investigate plastic changes following odor conditioning and, in particular, possible variations in number and morphology of the synapses involved in the ALs circuitry.
Journal of Insect Physiology
Methods in molecular biology (Clifton, N.J.), 2018
This chapter describes how to apply two-photon neuroimaging to study the insect olfactory system ... more This chapter describes how to apply two-photon neuroimaging to study the insect olfactory system in vivo. It provides a complete protocol for insect brain functional imaging, with some additional remarks on the acquisition of morphological information from the living brain. We discuss the most important choices to make when buying or building a two-photon laser-scanning microscope. We illustrate different possibilities of animal preparation and brain tissue labeling for in vivo imaging. Finally, we give an overview of the main methods of image data processing and analysis, followed by a short description of pioneering applications of this imaging modality.