Despite being one of the few human-specific types of play that humans of various ages engage in, games are understudied in cross-cultural research. Games are not distributed randomly across cultures and vary with some socio-ecological aspects of human cultures. Previous observational studies suggest that the cooperativeness and egalitarianism of cultural groups is reflected in the games that are played across cultures, but this has yet to be studied using a breadth of method- ological approaches. In this dissertation, I investigate the relationship the cooperativeness of games may have with the cooperativeness of cultural groups and offer one potential avenue as to how and why games are distributed across cultures. This dissertation consists of two main parts. The first part (chapters 2 - 3) focuses on gathering and analyzing descriptions of historical games and cultural levels of cooperation from ethnolinguistic groups on the Austronesian language phylogeny. The second part (chapters 4 - 6) focuses on gathering games, cultural levels of cooperation, and investigating the relationship between games and cultural levels of cooperation by three modern-day cultural groups. In chapter two, I describe the making of the Austronesian Game Taxonomy, an open-access database of game descriptions as gathered from historical, ethnographic, and other sources. I also describe my goal structure coding scheme and apply it to the 907 games in the Austronesian Game Taxonomy. In chapter three, I test the relationship between the goal structure of games from the Austronesian Game Taxonomy and several proxies for cultural levels of cooperation in 25 ethnolin- guistic groups. I find that the cooperativeness of games is negatively related to cultural levels of intra-group conflict and positively related with inter-cultural conflict. The goal structure of games is not associated with the social structure of cultures, nor reliably correlate with measures of interdependence in subsistence. Chapter four provides a detailed description of the three cultures that are the focus of Part two of this dissertation: Hai||om and Ovambo in Namibia, and Germans in Leipzig, Germany. I use three semi-structured interviews to obtain information about the levels of social stratification, intra-group conflict, and inter-cultural conflict experienced by these three groups. Chapter five documents the games played by Hai||om and Ovambo children and adults during my research visit to Namibia. I describe a handful of games with variety of goal structures. I provide the interview used to gather this information for future cross-cultural game collection. In chapter six, I examine the relationship between the preference for games that are cooperative or competitive, and cultural levels of cooperation in three modern-day cultures. I also interview caretakers on their attitudes toward children’s play and games. I find cross-cultural variation in children’s game preferences, but adult game preferences do not vary across cultures. Game preferences do not systematically vary with predicted cultural levels of cooperation. In the general discussion, I discuss my research findings in terms of the relationship between games and cultural levels of cooperation and suggest further improvements for the field of cross-cultural game research. This dissertation provides some evidence that games relate with types of conflict, but not with levels of social stratification nor interdependence in subsistence.

Assembly and functions of cilia rely on the continuous transport of ciliary components between the cell body and the ciliary tip. This is performed by specialized molecular machines, known as Intraflagellar Transport (IFT) trains. Anterograde IFT trains are powered by kinesin-2 motors and move along the B-tubules of the microtubule doublets. Conversely, retrograde IFT trains are moved by dynein-2 motors along the A-tubules back to the cell body. The segregation of oppositely directed trains on A-tubules or B-tubules is thought to prevent traffic jams in the cilium, but the mechanism by which opposite polarity trains are sorted on either tubule is unknown. It has been reported that A-tubule and B-tubule are differentially enriched in tyrosinated and detyrosinated tubulins, but whether this difference has a role in IFT regula2on is not understood. Here, I show that CRISPR knock out of VASHL, the enzyme that detyrosinates microtubules, causes repeated collisions between oppositely directed trains and reduces the rate of ciliary growth. To test whether this is ascribable to direct interaction between IFT trains and tubulin detyrosination/tyrosination, I developed a method to reconstiute the motility of native IFT trains from Chlamydomonas reinhardtii cilia ex-vivo on synthetically polymerized microtubules enriched for either tubulin post-translational modification. I show that retrograde trains have higher affinity for tyrosinated microtubules (analogous to A-tubules), while anterograde trains for detyrosinated microtubules (analogous to B-tubules). I conclude that tubulin tyrosination/detyrosination is required for the spatial segregation of oppositely directed trains and for their smooth uninterrupted motion. My results provide a model for how IFT motility is governed by the underlying tubulin code.:Table of Contents Abstract ............................................................................................................................. 4 1. Introduc1on .................................................................................................................. 7 1.1 Cilia ............................................................................................................................................... 7 1.1.1 Cilia are ubiquitous and important cell organelle ................................................................................ 7 1.1.2 Pathologies associated with Ciliary dysfunc=on .................................................................................. 7 1.1.3 Axoneme is the structural scaffold of the cilium ................................................................................. 8 1.2 Intraflagellar transport (IFT) ....................................................................................................... 11 1.2.1 IFT complex is large macromolecular protein assembly .................................................................... 11 1.2.2 Microtubule motors drive the IFT trains ............................................................................................ 12 1.3 Bidirec<onal transport by microtubule cytoskeleton motors .................................................... 16 1.3.1 Microtubules ...................................................................................................................................... 16 1.3.2 Kinesin ............................................................................................................................................... 18 1.3.3 Dynein ................................................................................................................................................ 21 1.3.4 Mul=-motor transport ....................................................................................................................... 24 1.3.5 Cargo Logis=cs ................................................................................................................................... 27 1.4 Aims of the thesis ....................................................................................................................... 34 2. Ex-vivo Recons1tu1on of IFT train mo1lity ................................................................... 36 2.1 Capillary micropipeGe can be coupled with TIRFM for IFT train recons<tu<on ........................ 36 2.2 Ex-vivo mo<lity of IFT trains ....................................................................................................... 41 2.3 Ex-vivo trains retain their complex iden<ty ................................................................................ 43 3. Role of tubulin tyrosina1on/detyrosina1on in train sor1ng ......................................... 46 3.1 Chlamydomonas VashL encodes for axonemal tubulin detyrosina<on ac<vity ......................... 47 3.2 Anterograde IFT trains exhibit collisions in Chlamydomonas VashL mutant .............................. 48 3.3 Anterograde trains have a stronger affinity for normal ghost axonemes ................................... 51 3.4 The affinity of anterograde trains reduces for VashL ghost axonemes ...................................... 51 3.5 Retrograde trains are more likely to land on detyrosinated microtubules ................................ 53 4. Sidestepping as a IFT sor1ng mechanism ..................................................................... 57 4.1 2D tracking of IFT trains reveals off-axis stepping component ................................................... 57 4.2 IFT trains do not collide when crossing on microtubules ........................................................... 61 5. Discussion and Outlook ............................................................................................... 63 6. Materials and Methods ............................................................................................... 71 6.1 Chlamydomonas Cell Culture ..................................................................................................... 71 6.2 Crea<on of IFT-46 mNeonGreen::VashL ..................................................................................... 71 6.3 Coverslip Prepara<on ................................................................................................................. 72 6.4 Capillary pipeGe prepara<on and manipula<on ........................................................................ 72 6.5 Microtubule Polymeriza<on and polarity labeling ..................................................................... 73 6.6 Enzyme treatments of Microtubules .......................................................................................... 73 6.7 TIRF Microscopy ......................................................................................................................... 74 6.8 Analysis of TIRFM data ............................................................................................................... 74 6.9 Kymographs of Ghost Axonemes: .............................................................................................. 75 6.10 Flagella Isola<on ...................................................................................................................... 75 6.11 Western Blo_ng ...................................................................................................................... 76 6.12 Par<cle tracking in FIESTA ........................................................................................................ 76 7. Step-by-step protocol for IFT mo1lity recons1tu1on .................................................... 78 7.1 Materials .................................................................................................................................... 78 7.2 Method ...................................................................................................................................... 79 Bibliography .................................................................................................................... 86 Acknowledgements ......................................................................................................... 98 Declara1on according to §5.5 of the doctorate regula1ons ............................................ 100

Seed dispersal is crucial for plants to colonize new habitats and facilitate gene flow between populations. However, Pleistocene extinctions of large-bodied fruit-eating and seed-dispersing animals, known as ‘megafrugivores’, may have hindered the dispersal of plants with large fruits (> 4cm fruit length – ‘megafruits’). Plants with megafruits are common across the flora of Madagascar, especially within the palm (Arecaceae) family. This dissertation investigates the macro-ecological and micro-evolutionary consequences of dispersal limitation on palms with megafruits in Madagascar. Specifically, I investigated three key aspects: (i) turnover or beta-diversity of palms on Madagascar and the distribution of their dispersal-related traits, (ii) the genetic diversity and genetic structure of three palms with megafruits compared to one palm with small fruits, and (iii) population size and migration rate changes over time of several Malagasy palm species with different ecological characteristics. To address these questions, historical ranges of extinct megafrugivores were reconstructed based on fossil sites, and data on extant frugivores, human activities, and climate were collected. Fieldwork in Madagascar provided genetic data for 12 palm species across 46 populations, from which I generated double digest restriction-site associated DNA sequencing data. Various interdisciplinary methods were employed, including redundancy analyses, variation partitioning, linear mixed effect models, species distribution models, and demographic modelling. The findings indicate that the current turnover of palms in Madagascar is primarily influenced by extant frugivores and climate, with limited impact from extinct frugivores. Surprisingly, there is no evidence of decreased genetic diversity or increased genetic differentiation in megafruited palms due to the loss of their megafrugivore dispersers. Genetic diversity is positively associated with human population density but negatively influenced by road densities, possibly reflecting habitat fragmentation by humans. Connectivity between populations is linked to the number of shared extinct and extant (mega)frugivore species, for megafruited and small-fruited palm populations, respectively. This highlights the importance of past long-distance dispersal events by megafrugivores and human-mediated dispersal possibly maintaining connectivity for megafruited palms. Population declines are observed across palms since the Last Glacial Maximum, particularly in humid forest species rarely used by humans, while humid forest species with megafruits show recent migration disruption. In contrast, palm species with smaller fruits that are highly used by humans show less pronounced declines and more stable historical migration rates. Overall, this dissertation illustrates that while the role of megafrugivores as seed dispersers is still evident in the genome of megafruited palms, other factors such as human-mediated dispersal and climate have an influence over the distribution, genetics and demographic histories of palms in Madagascar. It further shows how integrating genetic data with ecological data on species distributions, climate, human activities, can provide novel insights into the drivers of different facets of biodiversity of such a diverse group of plants such as palms.:Chapter 1 - General introduction ....................................................................................... 7 Background and problem statement...................................................................................... 7 Plant seed dispersal, fleshy fruits and frugivory ............................................................ 7 Megafauna and megafruits ............................................................................................ 9 Thesis scope .......................................................................................................................... 12 Madagascar as a model system .................................................................................... 12 Palms as a model system .............................................................................................. 16 Thesis aims and importance ................................................................................................. 19 Overview of methodologies used ......................................................................................... 19 Field data collection ..................................................................................................... 19 Double digest restriction-site associated DNA (ddRAD) .............................................. 21 Outline of the thesis ............................................................................................................. 22 Chapter 2 - Megafrugivores as fading shadows of the past: extant frugivores and the abiotic environment as the most important determinants of the distribution of palms in Madagascar .................................................................................................................... 25 Chapter 3 - Genomic signatures of past megafrugivore-mediated dispersal in Malagasy palms ............................................................................................................................. 39 Chapter 4 - Insights into the demographic history of Malagasy palms: exploring the role of global change and species-specific characteristics ........................................................... 57 Chapter 5 – General discussion ....................................................................................... 73 Summary and key findings.................................................................................................... 73 The fate of megafruited plants in the post-megafrugivore era ........................................... 74 Vulnerability and resilience in megafruited plants .............................................................. 76 Understanding the complex role of humans in the distribution and genetics of megafruited plants ……………………………………………………………………………………………………………………………..77 The influence of abiotic factors over the distribution and genetics of Malagasy palms ..... 78 Outlook ................................................................................................................................. 79 References ...................................................................................................................... 83 Appendix ...................................................................................................................... 101 Appendix Chapter 2 ............................................................................................................ 101 Appendix Chapter 3 ............................................................................................................ 123 6 Appendix Chapter 4 ............................................................................................................ 145 Summary ...................................................................................................................... 159 Zusammenfassung ........................................................................................................ 163 Acknowledgments ........................................................................................................ 169 Curriculum Vitae ..................................................................................................................... 171 List of publications and scientific presentations .................................................................... 171 Selbstständigkeitserklärung……………………………………………………………………………………….……..168

Metabolic coupling between glial cells and neurons is essential for neuronal function. It is a well-conserved and vital feature of the bilaterian nervous system as well. Under normal and adverse conditions, glial cells act as a major metabolic hub fueling neuronal oxidative metabolism by producing lactate or ketone bodies. I now ask the question of whether such metabolic coupling is only necessary for preserving brain homeostasis or if it could also have implications in decision making such as food choice behavior. Choosing an appropriate food source is key for the survival of an organism. Carbohydrates are the preferred source of energy and thus evaluation of their nutritive content is essential. Several studies have demonstrated that Drosophila melanogaster larvae and adults, as mammals, can distinguish between nutritious and non-nutritious carbohydrates independent of their taste. Two groups of neurons, Diuretic Hormone 44 (Dh44)-expressing neurons and gustatory receptor 43a (Gr43a)-expressing neurons, have been implicated in postprandial sugar sensing in adult flies. Gr43a- expressing neurons are narrowly fine-tuned for sensing fructose in both adults and larvae. Nonetheless, in the larva, central nervous system (CNS) Gr43a neurons have been shown to act as the main sugar sensor. This raises the question of how CNS fructose-sensing neurons are involved in sensing non-fructose dietary sugars. To decipher this post-ingestive mechanism, I used frustrated total internal reflection (FTIR) - based larval tracking to investigate larval food choice behavior. The results present in this thesis suggest that besides Gr43a-expressing neurons, glial cells are indispensable for sensing nutritive non-fructose dietary sugars such as glucose and sorbitol. I show that post-ingestive carbohydrate sensing involves carbohydrate conversion into fructose locally in the glial cells. Glia-derived fructose then enables Gr43a-dependent postprandial carbohydrate sensing in the CNS and drives carbohydrate preferences with the help of the downstream signalling peptide corazonin. Thus, in post-ingestive carbohydrate sensing, the glial cells act as a master metabolite sensor and provide a fructose stimulus to neurons to regulate behavior.:Table of Contents Abstract 1 Zusammenfassung 2 1. Introduction 3 1.1. External Nutrient Sensing in mammals and Drosophila melanogaster 4 1.1.1. Taste detection in mammals 4 1.1.2. Taste detection in Drosophila melanogaster 6 1.1.3 Sweet and Umami Taste in mammals 8 1.1.4. Sweet Sensing in Drosophila melanogaster 8 1.1.5. Bitter Taste in mammals 9 1.1.6. Bitter Sensing in Drosophila melanogaster 9 1.1.7. Sour, Carbonation, Fatty acid and Salty taste in mammals 9 1.1.8. Amino acid, Fatty acid and Salt Sensing in Drosophila melanogaster 10 1.2 Post-ingestive nutrient sensing in mammals and Drosophila melanogaster 11 1.2.1. Post-ingestive amino acid sensing in mammals 11 1.2.2. Post-ingestive amino acid sensing in Drosophila melanogaster 12 1.2.3. Post-ingestive lipid sensing in mammals 13 1.2.4. Post-ingestive carbohydrate sensing in mammals 13 1.2.4.1. The role of the nervous system in post-ingestive carbohydrate sensing mammals 16 1.2.5. Post-ingestive carbohydrate sensing in Drosophila melanogaster 16 1.2.5.1. The role of the nervous system in post-ingestive carbohydrate sensing in flies 18 1.2.5.2. The role of the nervous system in post-ingestive carbohydrate sensing in larvae 19 1.3 The cellular architecture of the larval nervous system 20 1.3.1 The Blood-brain barrier (BBB) and carbohydrate transport 23 1.4 Aim of study 25 2. Experimental Procedures 26 2.1 Materials 26 2.1.1 Chemicals 26 2.1.2 Media 27 2.1.3 Buffer and Solution 27 2.1.4 Antibodies 28 2.1.5 Flystocks 29 2.2 Methods 33 2.2.1 Fly genetics 33 2.2.1.1 Maintenance and crosses 33 2.2.2 Immunohistochemistry & Microscopy 33 2.2.2.1 Immunohistochemistry of larval filets 33 2.2.2.2 Confocal Microscopy 33 2.3 Experimental Design 34 2.3.1 Studying food choice in Drosophila larvae 34 2.3.1.1 Concept 34 2.3.1.2 Experimental setup 36 2.3.1.3 Analysis 36 2.3.1.4 MATLAB Script 38 3. Results 40 3.1. Frustrated total internal reflection based two-choice assay (TCA) 40 3.1.1 Investigating larval sugar preference 40 3.2 The role of diuretic hormone 44 (Dh44) neurons in post-ingestive glucose sensing in third instar larvae 47 3.2.1 Immunohistochemical analysis of Dh44 in third instar larval brains 47 3.2.2 Role of Dh44 in glucose sensing 49 3.3 The role of gustatory receptor 43a (Gr43a) neurons in post-ingestive nutritive carbohydrate sensing in third instar larvae 51 3.3.1 Immunohistochemical analysis of Gr43a in third instar larval brains 51 3.4. Investigating the role of polyol pathway in post-ingestive carbohydrate sensing 56 3.4.1 Identifying the key polyol pathway enzyme in Drosophila melanogaster 56 3.4.2 Examining RNAi mediated neuronal and glial knockdown of polyol pathway enzymes in postprandial sugar sensing 57 3.4.2.1 CG9436 57 3.4.2.2 CG6084 and CG10863 60 3.4.2.3 Sodh-2 66 3.5 Determining the glia subtypes vital for conducting polyol pathway 69 3.6 The role of the blood brain barrier (BBB) in post-ingestive carbohydrate sensing 74 4. Discussion 80 4.1. Gr43a is the only sugar sensor in Drosophila larvae 80 4.2. Polyol Pathway is crucial for glucose and sorbitol sensing 82 4.3. Glia, the master metabolic sensor 84 4 4. Transport over BBB: a prerequisite for postprandial carbohydrate sensing85 4.5. Proposed model for larval post-ingestive nutritive carbohydrate sensing... 86 5. References 89 6. Abbreviation List 100 7. Appendix 103

During morphogenesis, epithelial tissues undergo dramatic changes in shape, transitioning from flat sheets to three-dimensional folded structures. This remarkable transformation relies on dynamic changes in mechanical tension at both their apical and basal surfaces. While it is well-established that the generation of mechanical tension at the apical side is driven by the actomyosin network, research on this process has often overlooked the generation of mechanical tension at the basal surface. Moreover, the mechanical response to stress, encompassing both elastic (spring-like) and viscous (fluid-like) properties, is important for epithelial transformations, yet this mechanical response is poorly understood for the basal cell surface. In this thesis, we investigated how basal tension is influenced by the basement membrane - an extracellular matrix layer which has been widely regarded as a passive scaffold for cells. We probed the material mechanical response of the basement membrane and directly measured and analyzed basal tension in the wing imaginal disc epithelium of Drosophila. To study the mechanical response, I used long-term confocal imaging and fluorescence recovery after photobleaching (FRAP) to analyze the turnover and mobility of Collagen IV, a component of the basement membrane. The low Collagen IV mobility and turnover (≈ 40 hours) suggest a solid-like behavior of the basement membrane at the time scale of hours. Moreover, Atomic Force Microscopy (AFM) force-indentation curves reveal low hysteresis and an elastic solid-like response. To measure basal mechanical tension, I probed the basement membrane with an AFM. Interpreting the results of AFM shallow indentations on the basal side of explanted wing discs as indenting into a fixed, elastic, stretched thin film, I investigated in control conditions and after molecular perturbations basal mechanical tension. Mechanical tension was ≈ 0.4 mN/m. The removal of collagen IV by collagenase significantly reduced basal tension while increasing basal cell surface area. In addition, inhibition of actomyosin activity through different reagents reduces basal tension while decreasing basal cell surface area. These results indicate that basal tension depends on both the ECM and actomyosin activity. They also indicate that the basement membrane is under expansile stress. Finally, to further investigate the mechanisms underlying the generation of stretch in the basement membrane, I analyzed the influence of hydrostatic pressure and actomyosin contractility along the lateral cell surfaces. These mechanisms exert mechanical forces that increase basal cell area, inducing a stretch in the basement membrane. Mild hypo- or hyperosmotic shocks resulted in increased or decreased basal cell area and basal tension, respectively. Moreover, optogenetic activation of actomyosin at lateral cell surfaces resulted in an increase in both basal cell area and basal tension. In summary, our research quantifies basal tension and unveils that the basement membrane is an elastic material (at time scale of hours). Furthermore, our data suggest that the basement membrane is under elastic stretch generated by hydrostatic pressure and actomyosin contractility. Thus, rather than being a passive scaffold for cells, the elastic properties of the basement membrane contribute to basal tension and thereby the shaping of cells and tissues.

Thermal food processing leads to the formation of advanced glycation end products (AGE) such as Nε-carboxymethyllysine (CML). Accordingly, these non-canonical amino acids are an important part of the human diet. However, CML is only partially decomposed by our gut microbiota and up to 30% are excreted via faeces and, hence, enter the environment. In frame of this study, we isolated a soil bacterium that can grow on CML as well as its higher homologue Nε-carboxyethyllysine (CEL) as sole source of carbon. Bioinformatic analyses upon whole-genome sequencing revealed a subspecies of Pseudomonas asiatica, which we named ‘bavariensis’. We performed a metabolite screening of P. asiatica subsp. bavariensis str. JM1 grown either on CML or CEL and identified N-carboxymethylaminopentanoic acid and N-carboxyethylaminopentanoic acid respectively. We further detected α-aminoadipate as intermediate in the metabolism of CML. These reaction products suggest two routes of degradation: While CEL seems to be predominantly processed from the α-C-atom, decomposition of CML can also be initiated with cleavage of the carboxymethyl group and under the release of acetate. Thus, our study provides novel insights into the metabolism of two important AGEs and how these are processed by environmental bacteria.

Despite remarkable advances in therapeutic interventions, malignant melanoma (MM) remains a life-threating disease. Following high initial response rates to targeted kinase-inhibition metastases quickly acquire resistance and present with enhanced tumor progression and invasion, demanding alternative treatment options. We show 2nd generation hexameric TRAIL-receptor-agonist IZI1551 (IZI) to effectively induce apoptosis in MM cells irrespective of the intrinsic BRAF/NRAS mutation status. Conditioning to the EC50 dose of IZI converted the phenotype of IZI-sensitive parental MM cells into a fast proliferating and invasive, IZI-resistant metastasis. Mechanistically, we identified focal adhesion kinase (FAK) to play a dual role in phenotype-switching. In the cytosol, activated FAK triggers survival pathways in a PI3K- and MAPK-dependent manner. In the nucleus, the FERM domain of FAK prevents activation of wtp53, as being expressed in the majority of MM, and consequently intrinsic apoptosis. Caspase-8-mediated cleavage of FAK as well as FAK knockdown, and pharmacological inhibition, respectively, reverted the metastatic phenotype-switch and restored IZI responsiveness. FAK inhibition also re-sensitized MM cells isolated from patient metastasis that had relapsed from targeted kinase inhibition to cell death, irrespective of the intrinsic BRAF/NRAS mutation status. Hence, FAK-inhibition alone or in combination with 2nd generation TRAIL-receptor agonists may be recommended for treatment of initially resistant and relapsed MM, respectively.

Pressure-overload-induced cardiac hypertrophy represents one cause of the development of heart failure. The aim of this study is to characterize the influence of the TIR-domain-containing adapter-inducing interferon- (TRIF) during afterload-induced myocardial remodeling. After transaortic constriction (TAC), cardiac pressure overload leads to an early increase in MyD88- (Myeloid differentiation primary response gene 88) and TRIF-dependent cytokines. The maximum cytokine expression appeared within the first week and decreased to its control level within five weeks. While cardiomyocyte hypertrophy was comparable, the myocardial accumulation of the inflammatory cells was lower in TRIFmice. At d7, TRIF deficiency reduced transcription factors and TRIF-dependent cytokines. Through the modulation of the TGF-signaling pathway and anti-fibrotic microRNAs, TRIF was involved in the development of interstitial fibrosis. The absence of TRIF was associated with a decreased expression of proapoptotic proteins. In echocardiography and working heart analyses, TRIF deficiency slowed left-ventricular wall thickening, myocardial hypertrophy, and reduces the ejection fraction. In summary, TRIF is an important adapter protein for the release of inflammatory cytokines and the accumulation of inflammatory cells in the early stage of maladaptive cardiac remodeling. TRIF is involved in the development of cardiac fibrosis by modulating inflammatory and fibrotic signal transduction pathways.

Over the last decades, imaging methods in animal models underwent revolutionary developments. Yet the potential of novel and accurate techniques for the imaging of neural substrates realizes fully only through interaction with human research and its system-level understanding of brain function. For instance, cross-species investigation is fundamental for auditory neuroscience, in particular in the study of sound source localization processing. The translation of auditory spatial cues into their neural representation has been addressed in multiple studies across species, allowing the development of theoretical and functional models of auditory space. However, auditory localization within the vertical plane remains less explored, with few animal studies addressing the neuroscience of elevation perception in the cortex. The study presented here aims to set the basis to bridge this knowledge gap, leveraging the interaction of human and animal neuroscience. Recent human studies identified an inverse linear relationship between sound source elevation and cortical activity and revealed remarkable plasticity in auditory cortical tuning for elevation. Building on these results, our laboratory conducted an Electroencephalography (EEG) experiment with human subjects. That study confirmed that sound source elevation is represented in a systematic manner in the human auditory cortex, but did not elucidate how the cortical substrate supports this representation. In fact, EEG lacks the spatial resolution to fully investigate the generators of the signals it measures, the circuital components of the auditory cortex. To bypass this challenge, we can assess if the same experimental protocol can yield similar results in a mouse model, the substrates of which can then be interrogated with molecular imaging tools. The results of such circuital dissection do not necessarily translate back to human research but can inform and guide its explorations provided solid theoretical basis and supporting computational models. Thus, in this dissertation we develop a comprehensive experimental platform for mouse EEG, aiming to translate protocols from human cognitive neuroscience to animal models. This translation, and its validation, lays the groundwork for further interrogation of the neural substrates of auditory perception and is the purpose of two experiments we present at the end of this thesis. We dedicate Chapter 1 to highlighting the necessity of integrating human and animal models to comprehend cortical functions and their implications for complex behavior. To further demonstrate the potential of this approach, in Chapter 2 we highlight the importance of omission responses, corollary discharge, and mismatch negativity (MMN) research from an interactionist standpoint, further showcasing how animal models can elucidate circuit-level substrates and contribute to multisensory integration theories. This investigation requires a deep understanding of spatial audition, and to this end in Chapter 3, we provide such detailed exploration, focusing on the auditory system's ability to localize sound within a three-dimensional space. In Chapter 4 we detail the modular setup for mouse EEG and imaging that we developed from scratch as part of this doctoral work. This setup is designed to facilitate the precise delivery of auditory stimuli and the accurate recording of EEG and optical imaging data under controlled conditions. The modular design philosophy centers on the integration of a robotic surgery station, anesthesia system, stimulus delivery system, optical imaging, and EEG systems in an integrated station, ensuring seamless transfer between different stations depending on the experiment requirements. We overview these components in the hardware section, which also describes the auditory stimulation system with its speaker arch that can be employed in a horizontal or vertical position. We also describe the surgical station, highlighting the modified stereotaxic apparatus and the surgical robot that allows for automated skull drilling and electrode array placement with micrometer-level precision. In the EEG systems section, we delineate the two types of EEG apparatus used in the experiments: subcutaneous needle electrodes (SNE) and multielectrode array (MEA). We discuss the advantages and drawbacks of SNE, the electrode positioning, and the importance of the reference and ground electrodes. We also describe the MEA system, emphasizing its high-density recordings and reduced movement artifacts. Finally, in the workflow section, we outline the sequence of operations for the experiments, from electrode implantation to processor initialization and stimulus presentation. We detail the electrode implantation procedures for both SNE and MEA, the initialization of processors and software for managing the EEG and stimulation systems, and the Python experimental platform that integrates all these components into a cohesive experimental protocol. We first employed this setup for the experiment detailed in Chapter 5 to explore the processing of sound source elevation in mice employing an adapter-probe paradigm. The aim was to assess whether it would yield comparable results to its application in humans. This paradigm is designed to induce short-term auditory adaptation, which leads to a decrease in neural responses to stimuli. By utilizing an adapter stimulus without local cues, we prevent suppression of location-specific processing, while silencing other sound-responsive neurons. We then present probe stimuli from different elevations, the responses to which should be dependent on the elevation modulation rather than the auditory processing suppressed by the adapter. This strategy allows us to record elevation-specific EEG activity with a better signal-to-noise ratio than would be otherwise possible. With this approach, we measured ERP components that align with those documented in humans, with a typical latency shift. Among these components, we identified a novel ERP correlate of sound source elevation processing in mice. This neural signature consists of a slow-rising mid-latency ERP component, which parallels the one elicited by the same protocol in humans. However, the effect of elevation was small, and limited to a contrast between the response to central stimuli and those above and below the animal. Our results reinforce the notion that mice ERPs can be used to investigate sound source elevation, highlighting similarities between human and mouse auditory processing. However, these conclusions hinge on an additional exploration into whether the auditory system of anesthetized mice can reliably produce responses specific to sound elevation. We address this critical aspect in the experiment presented in Chapter 6. In this second experiment, we employed a mismatch paradigm to discern whether anesthetized mice could differentiate between high and low sound sources. This involved alternating each sound source elevation as a deviant within a regular sequence of stimuli at the same elevation. We hypothesized that if the mice's auditory system could distinguish these elevations, we would observe an MMN effect, indicated by more negative responses to deviant stimuli compared to standard ones. This effect would be more pronounced for deviant stimuli from elevations further from the standard than for those closer. To enhance our experimental setup, we utilized a proprietary MEA for improved standardization and spatial resolution. With this setup we observed a biphasic MMN, with two distinct negative deflections, confirming the auditory system's capability to process stimuli from different elevations. This finding was intriguing, also considering the importance of head movements in auditory spatial perception, as discussed earlier. The biphasic nature of MMN might reflect different stages of cortical processing, with the late MMN suggesting complex spectral comparison as a possible analog of the human late discriminative negativity. We also found that deviant stimuli at -30 and 90° elevation did not elicit mismatch responses when presented in experimental blocks where the standard was at a 60° distance, but did when the standard was at a 120° distance. This finding confirmed our initial hypothesis However, our results also highlighted the unique status of the 30° elevation stimulus. In contrast to other elevations, the 30° stimulus showed a more pronounced early adaptation, and elicited a strong MMN as a deviant in the 60° proximity scenario. This suggests a possible bias in auditory processing towards this elevation range, potentially influenced by top-down modulation. The distinct adaptation behavior of the 30° stimulus could be a consequence of such modulation, aligning with behavioral studies and electrophysiological findings in other species. Further, we proposed a model where MMN elicitation in mice depends on the proximity of the deviant to a preferred elevation angle, near 30°, and the distance of the standard from the deviant. Such model could capture the dynamics of elevation representation mismatch. To explore these effects, further experiments with additional conditions are needed, potentially leading to a quantitative model of elevation deviance. Finally, in Chapter 7 we further explore possible research directions that could follow the work presented here, beyond what was already introduced in the experimental chapters

Among the 33 human adhesion G-protein-coupled receptors (aGPCRs), a unique subfamily of GPCRs, only ADGRF4, encoding GPR115, shows an obvious skin-dominated transcriptomic profile, but its expression and function in skin is largely unknown. Here, we report that GPR115 is present in a small subset of basal and in most suprabasal, noncornified keratinocytes of the stratified epidermis, supporting epidermal transcriptomic data. In psoriatic skin, characterized by hyperproliferation and delayed differentiation, the expression of GPR115 and KRT1/10, the fundamental suprabasal keratin dimer, is delayed. The deletion of ADGRF4 in HaCaT keratinocytes grown in an organotypic mode abrogates KRT1 and reduces keratinocyte stratification, indicating a role of GPR115 in epidermal differentiation. Unexpectedly, endogenous GPR115, which is not glycosylated and is likely not proteolytically processed, localizes intracellularly along KRT1/10-positive keratin filaments in a regular pattern. Our data demonstrate a hitherto unknown function of GPR115 in the regulation of epidermal differentiation and KRT1.