4,689 research outputs found

    Modelling phenomenological differences in aetiologically distinct visual hallucinations using deep neural networks

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    Visual hallucinations (VHs) are perceptions of objects or events in the absence of the sensory stimulation that would normally support such perceptions. Although all VHs share this core characteristic, there are substantial phenomenological differences between VHs that have different aetiologies, such as those arising from Neurodegenerative conditions, visual loss, or psychedelic compounds. Here, we examine the potential mechanistic basis of these differences by leveraging recent advances in visualising the learned representations of a coupled classifier and generative deep neural network—an approach we call ‘computational (neuro)phenomenology’. Examining three aetiologically distinct populations in which VHs occur—Neurodegenerative conditions (Parkinson’s Disease and Lewy Body Dementia), visual loss (Charles Bonnet Syndrome, CBS), and psychedelics—we identified three dimensions relevant to distinguishing these classes of VHs: realism (veridicality), dependence on sensory input (spontaneity), and complexity. By selectively tuning the parameters of the visualisation algorithm to reflect influence along each of these phenomenological dimensions we were able to generate ‘synthetic VHs’ that were characteristic of the VHs experienced by each aetiology. We verified the validity of this approach experimentally in two studies that examined the phenomenology of VHs in Neurodegenerative and CBS patients, and in people with recent psychedelic experience. These studies confirmed the existence of phenomenological differences across these three dimensions between groups, and crucially, found that the appropriate synthetic VHs were rated as being representative of each group’s hallucinatory phenomenology. Together, our findings highlight the phenomenological diversity of VHs associated with distinct causal factors and demonstrate how a neural network model of visual phenomenology can successfully capture the distinctive visual characteristics of hallucinatory experience

    UMSL Bulletin 2023-2024

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    The 2023-2024 Bulletin and Course Catalog for the University of Missouri St. Louis.https://irl.umsl.edu/bulletin/1088/thumbnail.jp

    Graduate Catalog of Studies, 2023-2024

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    Splenic nerve bundle stimulation in acute and chronic inflammation

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    Splenic neurovascular bundle stimulation holds potential to treat acute and chronic inflammatory conditions. In the first part of the thesis, the available literature on the interactions between the immune system and nervous system in the intestine is summarized. Then, it is shown that a specialized T-cell, that can produce the neurotransmitter acetylcholine, resides in the gut an plays a dual role in the development of experimental colitis in mice. Furthermore, electrical splenic neurovascular bundle stimulation ameliorated the outcomes of colitis in mice and reversed transcriptomic changes in the gut that were induced by colitis. The second part of the thesis focused on the translation of splenic neurovascular bundle stimulation to the human situation. It is shown that there are significant changes between murine and human innervation of the spleen. Using computed tomography (CT) images the course and the characteristics of the splenic artery were described. These data were used to develop a cuff electrode that could be used for electrical stimulation of the splenic neurovascular bundle in humans. Finally, it was demonstrated that splenic neurovascular bundle stimulation in humans was safe and feasible in a pilot study with patients that underwent esophagectomy

    Life on a scale:Deep brain stimulation in anorexia nervosa

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    Anorexia nervosa (AN) is a severe psychiatric disorder marked by low body weight, body image abnormalities, and anxiety and shows elevated rates of morbidity, comorbidity and mortality. Given the limited availability of evidence-based treatments, there is an urgent need to investigate new therapeutic options that are informed by the disorder’s underlying neurobiological mechanisms. This thesis represents the first study in the Netherlands and one of a limited number globally to evaluate the efficacy, safety, and tolerability of deep brain stimulation (DBS) in the treatment of AN. DBS has the advantage of being both reversible and adjustable. Beyond assessing the primary impact of DBS on body weight, psychological parameters, and quality of life, this research is novel in its comprehensive approach. We integrated evaluations of efficacy with critical examinations of the functional impact of DBS in AN, including fMRI, electroencephalography EEG, as well as endocrinological and metabolic assessments. Furthermore, this work situates AN within a broader theoretical framework, specifically focusing on its manifestation as a form of self-destructive behavior. Finally, we reflect on the practical, ethical and philosophical aspects of conducting an experimental, invasive procedure in a vulnerable patient group. This thesis deepens our understanding of the neurobiological underpinnings of AN and paves the way for future research and potential clinical applications of DBS in the management of severe and enduring AN

    Morphometric reorganization induced by working memory training: perspective from vertex and network levels

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    Der sich beschleunigende globale Alterungsprozess und die Tatsache, dass sich die kog-nitiven Fähigkeiten mit dem Alter verschlechtern, was sich erheblich auf die Lebensquali-tät älterer Erwachsener auswirkt, insbesondere bei altersbedingten Störungen (z. B. kogni-tiver Beeinträchtigung, Demenz), weisen auf einen dringenden Bedarf an Ansätzen zum Schutz und zur Verbesserung der kognitiven Fähigkeiten sowie an Untersuchungen der neuronalen Substrate altersbedingter Veränderungen und der Neuroplastizität hin. Da man davon ausgeht, dass das Arbeitsgedächtnis (WM) die grundlegende Ursache für altersbe-dingte kognitive Beeinträchtigungen bei einer Vielzahl von kognitiven Fähigkeiten dar-stellt, ist das Arbeitsgedächtnistraining (WMT) zu einem aktuellen Thema und einem be-liebten Ansatz geworden. Frühere Studien haben gezeigt, dass das Arbeitsgedächtnistrai-ning (WMT) die kognitive Leistung verbessert. Die spezifischen Auswirkungen sowie die zugrunde liegenden neurobiologischen Mechanismen sind jedoch nach wie vor um-stritten. Ziel dieser Arbeit ist es, die durch das WMT induzierte neuronale strukturelle Plastizität auf mehreren Ebenen sowie die Verhaltenseffekte des WMT zu untersuchen. In der ers-ten Studie untersuchten wir die topographischen Veränderungen der Morphologie der grauen Substanz durch WMT, indem wir vier strukturelle Metriken (d.h. die kortikale Dicke, das kortikale Volumen, die kortikale Oberfläche und den lokalen Gyrifikationsin-dex, LGI) sowie die subkortikalen Volumina explorierten. Konkret wurden 59 gesunde Probanden mittleren Alters nach dem Zufallsprinzip entweder einem adaptiven WMT oder einer nicht-adaptiven Intervention zugewiesen. Alle Teilnehmer unterzogen sich vor und nach der 8-wöchigen WMT-Phase einer Neurobildgebung sowie kognitiven Tests. Vor und nach dem WMT wurden vier kortikale Metriken auf Scheitelpunktniveau und sieben subkortikale Volumina sowie die globale mittlere kortikale Dicke berechnet. Das wich-tigste Ergebnis war, dass die WMT-Gruppe im Vergleich zur aktiven Kontrollgruppe eine größere Zunahme der kortikalen Faltung in den bilateralen parietalen Regionen zeigte. Die Ergebnisse deuten darauf hin, dass strukturelle Veränderungen durch WMT in WM-bezogenen Regionen, insbesondere in parietalen Regionen, die Verarbeitung einer höhe-ren WM-Belastung erleichtern können. Darüber hinaus könnte die kortikale Faltung das relevanteste und plastischste Merkmal von WM und Lernen sein und WMT-Effekte stär-ker widerspiegeln als andere Metriken. Basierend auf den Ergebnissen der ersten Studie haben wir darüber hinaus untersucht, ob die trainingsinduzierten Effekte des WMT in der kortikalen Faltung auf Vertex-Ebene von topologischen Veränderungen begleitet werden. Zu diesem Zweck untersuchten wir in Studie zwei die durch WMT verursachte Plastizität auf Netzwerkebene mit Hilfe eines strukturellen Kovarianzansatzes (SC), der auf denselben Stichproben basiert. Es wurden gyrifikationsbasierte SC-Matrizen für jede Gruppe vor und nach dem Training sowie lon-gitudinale gyrifikationsbasierte SC-Matrizen erstellt. Innerhalb jeder Gruppe ergab die LGI-basierte SC-Analyse keine Hinweise auf WMT-induzierte Veränderungen der kor-tiko-kortikalen Verbindungen, weder in der WMT- noch in der aktiven Kontrollgruppe. Die Ergebnisse der longitudinalen SC-Analyse (unkorrigiert p < 0,005) zeigten, dass die trainingsinduzierten Veränderungen der kortikalen Faltungsintensität signifikante Unter-schiede zwischen Paaren von parietalen Regionen sowie Paaren von frontalen Regionen aufwiesen. Insgesamt deuten die kombinierten Ergebnisse dieser beiden Studien darauf hin, dass ers-tens WMT neuronale strukturelle Plastizität hervorrufen kann; zweitens die kortikale Fal-tung das relevanteste und plastischste Merkmal von WM und Lernen sein könnte, das die Auswirkungen von WMT besser widerspiegelt als andere Indikatoren auf Vertex-Ebene; und drittens die trainingsinduzierten lokalisierten Veränderungen der kortikalen Faltung von einem ähnlichen Muster vergleichbarer struktureller Veränderungen zwischen ROIs innerhalb der Regionen begleitet wurden. In Zukunft sind weitere Forschungen erforder-lich, um diese Ergebnisse zu wiederholen und zu validieren sowie um trainingsinduzierte topologische und topografische Veränderungen anhand einer breiteren Palette von Metri-ken und Eigenschaften zu untersuchen.The accelerating global aging process and the fact that cognitive abilities deteriorate with age, which has a significant impact on the quality of life of older adults, particularly those with age-related disorders (e.g., cognitive impairment, dementia), all point to an urgent need for approaches to protect and enhance cognitive abilities, as well as studies of the neural substrates of aging-related changes and neuroplasticity. Since working memory (WM) has been assumed to be the fundamental source of age-related cognitive impair-ments in a variety of cognitive abilities, working memory training (WMT) has become a hot topic as well as a popular approach. Previous studies have established that working memory training (WMT) improves cognitive performance. However, the specific effects, as well as the underlying neurobiological mechanisms, remain a matter of controversy. The purpose of this thesis is to investigate WMT-induced neural structural plasticity at multiple levels together with the behavioral effects of WMT. In study one, we investigated the topographic changes of grey matter morphology due to WMT by combining four structural metrics (i.e., cortical thickness (CT), cortical volume (CV), cortical surface area (CSA), and local gyrification index (LGI)) as well as subcortical volumes. Specifically, 59 healthy volunteers between the ages of 50 and 65 were randomly assigned to either an adaptive or a non-adaptive intervention. All participants underwent neuroimaging as well as cognitive testing before and after the 8-week intervention. Four cortical metrics at ver-tex level and seven subcortical volumes, as well as global mean cortical thickness, were calculated before and after the intervention. The most important finding was that the adap-tive WMT group showed greater increases in cortical folding in bilateral parietal regions in comparison to the active control group who performed the non-adaptive intervention. The results indicate that structural changes due to adaptive WMT in WM related regions, particularly parietal regions, may facilitate the processing of a higher WM load. In addi-tion, the cortical folding might be the most relevant and plastic feature of WM and learn-ing, reflecting WMT effects more than other metrics. Based on the findings of study one, we further asked whether the training-induced effects of WMT in cortical folding at vertex-level are accompanied by topological changes. To this end, study two investigated network-level plasticity due to WMT by using the struc-tural covariance (SC) approach based on the same samples. Gyrification based SC matri-ces for each group before and after training, together with longitudinal gyrification SC matrices, were constructed. Within each group, the LGI-based SC analysis revealed no evidence of WMT-induced changes in cortical-cortical connections, either in the WMT or the active control groups. The results of the longitudinal SC analysis (uncorrected p < 0.005) revealed that the training induced changes of cortical folding intensity showed sig-nificant difference between pairs of parietal regions as well as pairs of frontal regions. Overall, the combined findings of these two studies indicate that: firstly, WMT can pro-duce neural structural plasticity; secondly, cortical folding might be the most relevant and plastic feature of WM and learning, better reflecting the effects of WMT than other vertex-level indicators; and thirdly, the training induced localized changes in cortical folding were accompanied by the pattern of similar structural changes between ROIs within the regions. In the future, more research is required to replicate and validate these findings, as well as to investigate training-induced topological and topographic changes using a broader set of metrics and properties

    Scared Straight? Threat and Assimilation of Refugees in Germany

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    This paper studies the effects of local threat on cultural and economic assimilation of refugees, exploiting plausibly exogenous variation in their allocation across German regions between 2013 and 2016. We combine novel survey data on cultural preferences and economic outcomes of refugees with corresponding information on German respondents, and construct a threat index that integrates contemporaneous and historical variables. On average, refugees assimilate both culturally and economically. However, while refugees assigned to more hostile regions converge to German culture more quickly, they do not exhibit faster economic assimilation. Our evidence suggests that refugees exert more assimilation effort in response to local threat, but that higher discrimination prevents them from integrating more quickly in more hostile regions

    Tradition and Innovation in Construction Project Management

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    This book is a reprint of the Special Issue 'Tradition and Innovation in Construction Project Management' that was published in the journal Buildings
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