@phdthesis{Groh2005, author = {Groh, Claudia}, title = {Environmental influences on the development of the female honeybee brain Apis mellifera}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-17388}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2005}, abstract = {F{\"u}r die Honigbiene spielt der Geruchssinn eine entscheidende Rolle bei der Kommunikation innerhalb des Sozialstaates. Kastenspezifische, auf uweltbedingten Einfl{\"u}ssen basierende sowie altersbedingte Unterschiede im olfaktorisch gesteuerten Verhalten liefern ein hervorragendes Modellsystem f{\"u}r diese Studie, um die Entwicklung und Funktion neuronaler Plastizit{\"a}t im olfaktorischen System zu untersuchen. Diese Studie konzentriert sich auf Unterschiede zwischen K{\"o}niginnen und Arbeiterinnen, den beiden weiblichen Kasten innerhalb des Bienestaates, sowie auf umweltbedingte Plastizit{\"a}t. Diploide Eier, aus denen sich K{\"o}niginnen und Arbeiterinnen entwickeln, sind genetisch identisch. Dennoch entwickeln sich K{\"o}niginnen wesentlich schneller zum Adulttier als Arbeiterinnen, sind als Imago gr{\"o}ßer, leben wesentlich l{\"a}nger und zeigen andere Verhaltensweisen. Diese Unterschiede werden durch eine differentielle larvale F{\"u}tterung initiiert. Im Anschluss an das Larvenstadium und somit nach erfolgter Kastendetermination, entwickeln sich die Bienen {\"u}ber eine Puppenphase (verdeckelte Phase) zum Imago. Adulte Bienen klimatisieren das zentrale Brutareal auf einer mittleren Temperatur von 35°C konstant. Bienen, die bei niedrigeren Temperaturen innerhalb des physiologisch relevanten Bereichs aufwachsen, weisen Defizite im olfaktorischen Lernverhalten und in der Tanzkommunikation auf. M{\"o}gliche neuronale Korrelate f{\"u}r altersbedingte, temperatur- und kastenspezifische Unterschiede im olfaktorisch gesteuerten Verhalten sollten in dieser Arbeit betrachtet werden. Die strukturellen Analysen konzentrierten sich dabei auf prim{\"a}re (Antennalloben) und sekund{\"a}re (Pilzk{\"o}rper-Calyces)olfaktorische Verarbeitungszentren im Gehirn von sich entwickelnden und adulten Tieren beider Kasten. Synchron verdeckelte Brutzellen beider Kasten wurden unter kontrollierten Bedingungen im Inkubator herangezogen. Neuroanatomische Untersuchungen wurden an fixierten Gewebeschnitten mittels einer Doppelfluoreszenzf{\"a}rbung mit Fluor-Phalloidin und anti-Synapsin Immuncytochemie durchgef{\"u}hrt. Diese Doppelmarkierung erm{\"o}glichte die Visualisierung und Quantifizierung individueller Synapsenkomplexe (Microglomeruli) im Pilzk{\"o}rper-Calyx. Phalloidin bindet an verschiedene F-Aktin Isoformen und kann zum Nachweis von F-Aktin im Insektennervensystem verwendet werden. F-Aktin wird w{\"a}hrend der Entwicklung in Wachstumskegeln und in adulten Gehirnen in pr{\"a}synaptischen Endigungen und dendritischen Dornen exprimiert. Pr{\"a}synaptische Elemente wurden durch den Einsatz eines spezifischen Antik{\"o}rpers gegen das Drosophila-Vesikeltransportprotein Synapsin I charakterisiert. Mit Hilfe der konfokalen Laser-Scanning Mikroskopie wurde die exakte r{\"a}umliche Zuordnung der Fluoreszenzsignale anhand optischer Schnitte durch die Pr{\"a}parate realisiert. Anhand dieser Methodik konnten erstmals {\"u}ber reine Volumenanalysen hinausgehende Messungen zur synaptischen Strukturplastizit{\"a}t im Pilzk{\"o}rper-Calyx durchgef{\"u}hrt werden. Die Untersuchungen an Gehirnen in den verschiedenen Puppenstadien zeigten Unterschiede im Entwicklungsverlauf der Gehirne mit dem Fokus auf die Bildung antennaler Glomeruli und calycaler Microglomeruli. Unterschiede in der Gehirnentwicklung verdeutlichten die ontogenetische Plastizit{\"a}t des Gehirns der Honigbiene. Entsprechend der k{\"u}rzeren Puppenphase der K{\"o}niginnen bildeten sich sowohl antennale Glomeruli als auch alle Untereinheiten (Lippe, Collar, Basalring) des Calyx etwa drei Tage fr{\"u}her aus. Direkt nach dem Schlupf zeigten quantitative Analysen innerhalb der Pilzk{\"o}rper-Calyces eine signifikant geringere Anzahl an Microglomeruli bei K{\"o}niginnen. Diese neuronale Strukturplastizit{\"a}t auf verschiedenen Ebenen der olfaktorischen Informationsverarbeitung korreliert mit der kastenspezifischen Arbeitsteilung. Die Arbeit liefert Erkenntnisse {\"u}ber den Einfluss eines wichtigen kontrollierten Umweltparameters, der Bruttemperatur, w{\"a}hrend der Puppenphase auf die synaptische Organisation der adulten Pilzk{\"o}rper-Calyces. Bereits geringe Unterschiede in der Aufzuchtstemperatur (1°C) beeinflussten signifikant die Anzahl von Microglomeruli in der Lippenregion des Calyx beider weiblicher Kasten. Die maximale Anzahl an MG entwickelte sich bei Arbeiterinnen bei 34.5°C, bei K{\"o}niginnen aber bei 33.5°C. Neben dieser entwicklungsbedingten neuronalen Plastizit{\"a}t zeigt diese Studie eine starke altersbedingte Strukturplastizit{\"a}t der MG w{\"a}hrend der relativ langen Lebensdauer von Bienenk{\"o}niginnen. Hervorzuheben ist, dass die Anzahl an MG in der olfaktorischen Lippenregion mit dem Alter anstieg (~55\%), in der angrenzenden visuellen Collarregion jedoch abnahm (~33\%). Die in der vorliegenden Arbeite erstmals gezeigte umweltbedingte Entwicklungsplastizit{\"a}t sowie altersbedingte synaptische Strukturplastizit{\"a}t in den sensorischen Eingangsregionen der Pilzk{\"o}rper-Calyces k{\"o}nnte kasten- und altersspezifischen Anpassungen im Verhalten zugrunde liegen.}, subject = {Biene}, language = {en} } @phdthesis{Brandstaetter2010, author = {Brandstaetter, Andreas Simon}, title = {Neuronal correlates of nestmate recognition in the carpenter ant, Camponotus floridanus}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-55963}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {Cooperation is beneficial for social groups and is exemplified in its most sophisticated form in social insects. In particular, eusocial Hymenoptera, like ants and honey bees, exhibit a level of cooperation only rarely matched by other animals. To assure effective defense of group members, foes need to be recognized reliably. Ants use low-volatile, colony-specific profiles of cuticular hydrocarbons (colony odor) to discriminate colony members (nestmates) from foreign workers (non-nestmates). For colony recognition, it is assumed that multi-component colony odors are compared to a neuronal template, located in a so far unidentified part of the nervous system, where a mismatch results in aggression. Alternatively, a sensory filter in the periphery of the nervous system has been suggested to act as a template, causing specific anosmia to nestmate colony odor due to sensory adaptation and effectively blocking perception of nestmates. Colony odors are not stable, but change over time due to environmental influences. To adjust for this, the recognition system has to be constantly updated (template reformation). In this thesis, I provide evidence that template reformation can be induced artificially, by modifying the sensory experience of carpenter ants (Camponotus floridanus; Chapter 1). The results of the experiments showed that template reformation is a relatively slow process taking several hours and this contradicts the adaptation-based sensory filter hypothesis. This finding is supported by first in-vivo measurements describing the neuronal processes underlying template reformation (Chapter 5). Neurophysiological measurements were impeded at the beginning of this study by the lack of adequate technical means to present colony odors. In a behavioral assay, I showed that tactile interaction is not necessary for colony recognition, although colony odors are of very low volatility (Chapter 2). I developed a novel stimulation technique (dummy-delivered stimulation) and tested its suitability for neurophysiological experiments (Chapter 3). My experiments showed that dummy-delivered stimulation is especially advantageous for presentation of low-volatile odors. Colony odor concentration in headspace was further increased by moderately heating the dummies, and this allowed me to measure neuronal correlates of colony odors in the peripheral and the central nervous system using electroantennography and calcium imaging, respectively (Chapter 4). Nestmate and non-nestmate colony odor elicited strong neuronal responses in olfactory receptor neurons of the antenna and in the functional units of the first olfactory neuropile of the ant brain, the glomeruli of the antennal lobe (AL). My results show that ants are not anosmic to nestmate colony odor and this clearly invalidates the previously suggested sensory filter hypothesis. Advanced two-photon microscopy allowed me to investigate the neuronal representation of colony odors in different neuroanatomical compartments of the AL (Chapter 5). Although neuronal activity was distributed inhomogeneously, I did not find exclusive representation restricted to a single AL compartment. This result indicates that information about colony odors is processed in parallel, using the computational power of the whole AL network. In the AL, the patterns of glomerular activity (spatial activity patterns) were variable, even in response to repeated stimulation with the same colony odor (Chapter 4\&5). This finding is surprising, as earlier studies indicated that spatial activity patterns in the AL reflect how an odor is perceived by an animal (odor quality). Under natural conditions, multi-component odors constitute varying and fluctuating stimuli, and most probably animals are generally faced with the problem that these elicit variable neuronal responses. Two-photon microscopy revealed that variability was higher in response to nestmate than to non-nestmate colony odor (Chapter 5), possibly reflecting plasticity of the AL network, which allows template reformation. Due to their high variability, spatial activity patterns in response to different colony odors were not sufficiently distinct to allow attribution of odor qualities like 'friend' or 'foe'. This finding challenges our current notion of how odor quality of complex, multi-component odors is coded. Additional neuronal parameters, e.g. precise timing of neuronal activity, are most likely necessary to allow discrimination. The lower variability of activity patterns elicited by non-nestmate compared to nestmate colony odor might facilitate recognition of non-nestmates at the next level of the olfactory pathway. My research efforts made the colony recognition system accessible for direct neurophysiological investigations. My results show that ants can perceive their own nestmates. The neuronal representation of colony odors is distributed across AL compartments, indicating parallel processing. Surprisingly, the spatial activity patterns in response to colony are highly variable, raising the question how odor quality is coded in this system. The experimental advance presented in this thesis will be useful to gain further insights into how social insects discriminate friends and foes. Furthermore, my work will be beneficial for the research field of insect olfaction as colony recognition in social insects is an excellent model system to study the coding of odor quality and long-term memory mechanisms underlying recognition of complex, multi-component odors.}, subject = {Neuroethologie}, language = {en} } @phdthesis{Habenstein2021, author = {Habenstein, Jens}, title = {Neuropeptides in the brain of \(Cataglyphis\) \(nodus\) ants and their role as potential modulators of behavior}, doi = {10.25972/OPUS-24961}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-249618}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {An adequate task allocation among colony members is of particular importance in large insect societies. Some species exhibit distinct polymorphic worker classes which are responsible for a specific range of tasks. However, much more often the behavior of the workers is related to the age of the individual. Ants of the genus Cataglyphis (Foerster 1850) undergo a marked age-related polyethism with three distinct behavioral stages. Newly emerged ants (callows) remain more or less motionless in the nest for the first day. The ants subsequently fulfill different tasks inside the darkness of the nest for up to four weeks (interior workers) before they finally leave the nest to collect food for the colony (foragers). This thesis focuses on the neuronal substrate underlying the temporal polyethism in Cataglyphis nodus ants by addressing following major objectives: (1) Investigating the structures and neuronal circuitries of the Cataglyphis brain to understand potential effects of neuromodulators in specific brain neuropils. (2) Identification and localization of neuropeptides in the Cataglyphis brain. (3) Examining the expression of suitable neuropeptide candidates during behavioral maturation of Cataglyphis workers. The brain provides the fundament for the control of the behavioral output of an insect. Although the importance of the central nervous system is known beyond doubt, the functional significance of large areas of the insect brain are not completely understood. In Cataglyphis ants, previous studies focused almost exclusively on major neuropils while large proportions of the central protocerebrum have been often disregarded due to the lack of clear boundaries. Therefore, I reconstructed a three-dimensional Cataglyphis brain employing confocal laser scanning microscopy. To visualize synapsin-rich neuropils and fiber tracts, a combination of fluorescently labeled antibodies, phalloidin (a cyclic peptide binding to filamentous actin) and anterograde tracers was used. Based on the unified nomenclature for insect brains, I defined traceable criteria for the demarcation of individual neuropils. The resulting three-dimensional brain atlas provides information about 33 distinct synapse-rich neuropils and 30 fiber tracts, including a comprehensive description of the olfactory and visual tracts in the Cataglyphis brain. This three-dimensional brain atlas further allows to assign present neuromodulators to individual brain neuropils. Neuropeptides represent the largest group of neuromodulators in the central nervous system of insects. They regulate important physiological and behavioral processes and have therefore recently been associated with the regulation of the temporal polyethism in social insects. To date, the knowledge of neuropeptides in Cataglyphis ants has been mainly derived from neuropeptidomic data of Camponotus floridanus ants and only a few neuropeptides have been characterized in Cataglyphis. Therefore, I performed a comprehensive transcriptome analysis in Cataglyphis nodus ants and identified peptides by using Q-Exactive Orbitrap mass spectrometry (MS) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS. This resulted in the characterization of 71 peptides encoded on 49 prepropeptide genes, including a novel neuropeptide-like gene (fliktin). In addition, high-resolution MALDI-TOF MS imaging (MALDI-MSI) was applied for the first time in an ant brain to localize peptides on thin brain cryosections. Employing MALDI-MSI, I was able to visualize the spatial distribution of 35 peptides encoded on 16 genes. To investigate the role of neuropeptides during behavioral maturation, I selected suitable neuropeptide candidates and analyzed their spatial distributions and expression levels following major behavioral transitions. Based on recent studies, I suggested the neuropeptides allatostatin-A (Ast-A), corazonin (Crz) and tachykinin (TK) as potential regulators of the temporal polyethism. The peptidergic neurons were visualized in the brain of C. nodus ants using immunohistochemistry. Independent of the behavioral stages, numerous Ast-A- and TK-immunoreactive (-ir) neurons innervate important high-order integration centers and sensory input regions with cell bodies dispersed all across the cell body rind. In contrast, only four corazonergic neurons per hemisphere were found in the Cataglyphis brain. Their somata are localized in the pars lateralis with axons projecting to the medial protocerebrum and the retrocerebral complex. Number and branching patterns of the Crz-ir neurons were similar across behavioral stages, however, the volume of the cell bodies was significantly larger in foragers than in the preceding behavioral stages. In addition, quantitative PCR analyses displayed increased Crz and Ast-A mRNA levels in foragers, suggesting a concomitant increase of the peptide levels. The task-specific expression of Crz and Ast-A along with the presence in important sensory input regions, high-order integration center, and the neurohormonal organs indicate a sustaining role of the neuropeptides during behavioral maturation of Cataglyphis workers. The present thesis contains a comprehensive reference work for the brain anatomy and the neuropeptidome of Cataglyphis ants. I further demonstrated that neuropeptides are suitable modulators for the temporal polyethism of Cataglyphis workers. The complete dataset provides a solid framework for future neuroethological studies in Cataglyphis ants as well as for comparative studies on insects. This may help to improve our understanding of the functionality of individual brain neuropils and the role of neuropeptides, particularly during behavioral maturation in social insects.}, subject = {Cataglyphis}, language = {en} } @article{BeetzHechavarria2022, author = {Beetz, M. Jerome and Hechavarr{\´i}a, Julio C.}, title = {Neural processing of naturalistic echolocation signals in bats}, series = {Frontiers in Neural Circuits}, volume = {16}, journal = {Frontiers in Neural Circuits}, issn = {1662-5110}, doi = {10.3389/fncir.2022.899370}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-274605}, year = {2022}, abstract = {Echolocation behavior, a navigation strategy based on acoustic signals, allows scientists to explore neural processing of behaviorally relevant stimuli. For the purpose of orientation, bats broadcast echolocation calls and extract spatial information from the echoes. Because bats control call emission and thus the availability of spatial information, the behavioral relevance of these signals is undiscussable. While most neurophysiological studies, conducted in the past, used synthesized acoustic stimuli that mimic portions of the echolocation signals, recent progress has been made to understand how naturalistic echolocation signals are encoded in the bat brain. Here, we review how does stimulus history affect neural processing, how spatial information from multiple objects and how echolocation signals embedded in a naturalistic, noisy environment are processed in the bat brain. We end our review by discussing the huge potential that state-of-the-art recording techniques provide to gain a more complete picture on the neuroethology of echolocation behavior.}, language = {en} } @article{ZupancRoessler2022, author = {Zupanc, G{\"u}nther K. H. and R{\"o}ssler, Wolfgang}, title = {Government funding of research beyond biomedicine: challenges and opportunities for neuroethology}, series = {Journal of Comparative Physiology A}, volume = {208}, journal = {Journal of Comparative Physiology A}, number = {3}, doi = {10.1007/s00359-022-01552-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-325113}, pages = {443-456}, year = {2022}, abstract = {Curiosity-driven research is fundamental for neuroethology and depends crucially on governmental funding. Here, we highlight similarities and differences in funding of curiosity-driven research across countries by comparing two major funding agencies—the National Science Foundation (NSF) in the United States and the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). We interviewed representatives from each of the two agencies, focusing on general funding trends, levels of young investigator support, career-life balance, and international collaborations. While our analysis revealed a negative trend in NSF funding of biological research, including curiosity-driven research, German researchers in these areas have benefited from a robust positive trend in DFG funding. The main reason for the decrease in curiosity-driven research in the US is that the NSF has only partially been able to compensate for the funding gap resulting from the National Institutes of Health restricting their support to biomedical research using select model organisms. Notwithstanding some differences in funding programs, particularly those relevant for scientists in the postdoctoral phase, both the NSF and DFG clearly support curiosity-driven research.}, language = {en} }