157 research outputs found

    The psychological origins of the Hard Problem: How our consciousness is shaping the neuroscience of consciousness

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    The field of consciousness studies contains a substantial number of coexisting neurocognitive theories of consciousness. These theories vary in their initial definitions of what consciousness is, biasing scientific methods and measurement of the phenomenon, resulting in a divided science. Definitions of consciousness tend to vary along two lines: Either consciousness is seemingly reducible to physical and functional processes, indicating what is called access consciousness; or it constitutes a seemingly irreducible experience, indicating phenomenal consciousness. These two types of definitions correspond to two opposing camps on what is referred to as the hard problem of consciousness, also called the explanatory gap. While much effort has been spent by each camp either criticizing or defending the hard problem, little work has been done to explain why the two camps vary along these lines. In other words, there is a gap between our positions on the explanatory gap, which I label the “meta-gap”. In the current paper I contribute to bridging the meta-gap by attempting to explain and reconcile this basic disagreement in the field. By performing targeted literature searches, I answer seven research questions which serve as stepping stones to take us from problematic features of the field, to individual differences between researchers as a reason for these problems. My analysis of these individual differences results in two hypothesized psychological constructs: Internal and external explanatory focus. I conclude by indicating that solving the meta-gap involves becoming aware of our individual dispositions towards choosing different explanatory targets for consciousness.Masteroppgave i psykologiMAPSYK360INTL-HFINTL-KMDINTL-SVINTL-JUSMAPS-PSYKINTL-MNINTL-MEDINTL-PSY

    Sex Differences in Mood and Anxiety-Related Outcomes in Response to Adolescent Nicotine Exposure

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    Nicotine dependence is causally linked to increased risk of mood/anxiety disorders in later life. Females are reported to experience a higher prevalence of anxiety/depressive disorders and challenges in smoking cessation therapies, suggesting a potential sex-specific response to nicotine exposure and mood/anxiety disorder risk. However, pre-clinical evidence of sex-specific responses to adolescent nicotine exposure is unclear. Thus, to determine any sex differences in anxiety/depressive-related outcomes, adolescent male and female Sprague Dawley rats received nicotine (0.4 mg/kg; 3x daily) or saline injections for 10 consecutive days, followed by behavioural testing, in-vivo electrophysiology and Western Blot analyses. Our results revealed that adolescent nicotine exposure caused long-lasting anxiety/depressive-like behaviours, disrupted neuronal activity patterns and molecular signaling pathway targets in nicotine-treated male rats, but no significant effects in female cohorts, suggesting possible compensatory actions related to estrogen/progesterone signaling pathways in female. These novel results serve as a foundation for future investigations examining how adolescent nicotine exposure may differentially impact the male vs. female brains

    Behavioral Sex Differences Caused by Distinct Vasopressin Sources

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    Dysfunction in social communication is a prominent aspect of many psychopathologies and social disorders including autism, schizophrenia, and social anxiety. Consequently, development of clinical treatment for these disorders requires an understanding of neural circuitry underlying social communication. Sex differences are a persistent feature of social disorders, where autism is more prevalent in males, while social anxiety occurs more frequently in females. A critical gap in knowledge exists in understanding the role of sex-differences in the control of social behavior and communication. A reasonable hypothesis is that differences in neural circuitry underlie sex-differentiated dysfunctions in social behavior and communication. A well-studied circuit in this regard is the sexually dimorphic expression of the neuropeptide arginine vasopressin (AVP). AVP in the nervous system originates from several distinct sources which are, in turn, regulated by different inputs and regulatory factors. Using modern molecular approaches, we can begin to define the specific role of AVP cell populations in social behavior. We demonstrate a behavioral function for the sexually dimorphic AVP neurons in the bed nucleus of the stria terminalis (BNST) and in the paraventricular nucleus of the hypothalamus (PVN). Collectively, our results indicate that AVP cell groups appear to play opposite roles in social investigation by males and females, as BNST-AVP cell ablations and BNST AVP knockdown reduced male social approach, while PVN-AVP cell ablations increased female social approach. We next utilized circuit level tracing techniques to map the inputs and outputs of BNST and medial amygdala (MeA) AVP cells, which are the major source of sexually dimorphic AVP expression. Finally, we tested the function of several sexually dimorphic BNST-AVP projection areas, such as, the lateral septum (LS), lateral habenula (LHb), and dorsal raphe (DR). In male mice, but not female mice, optogenetic stimulation of the BNST AVP terminals in the LS increased their social investigation and anxiety-like behavior in the elevated-zero maze. Antagonism of V1aR in the LS blocked optogenetic-mediated increases in male social investigation and anxiety-like behavior. Therefore, activation of a distinct BNST-LS AVP circuit modulates sex-specific social approach and anxiety-like behavior, which is mediated by V1aR within the LS. This work suggests that sex differences in the neurochemical underpinnings of social behavior may contribute to sex differences in disorders of social behavior and communication

    Population-level neural coding for higher cognition

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    Higher cognition encompasses advanced mental processes that enable complex thinking, decision-making, problem-solving, and abstract reasoning. These functions involve integrating information from multiple sensory modalities and organizing action plans based on the abstraction of past information. The neural activity underlying these functions is often complex, and the contribution of single neurons in supporting population-level representations of cognitive variables is not yet clear. In this thesis, I investigated the neural mechanisms underlying higher cognition in higher-order brain regions with single-neuron resolution in human and non-human primates performing working memory tasks. I aimed to understand how representations are arranged and how neurons contribute to the population code. In the first manuscript, I investigated the population-level neural coding for the maintenance of numbers in working memory within the parietal association cortex. By analyzing intra-operative intracranial micro-electrode array recording data, I uncovered distinct representations for numbers in both symbolic and nonsymbolic formats. In the second manuscript, I delved deeper into the neuronal organizing principles of population coding to address the ongoing debate surrounding memory maintenance mechanisms. I unveiled sparse structures in the neuronal implementation of representations and identified biologically meaningful components that can be directly communicated to downstream neurons. These components were linked to subpopulations of neurons with distinct physiological properties and temporal dynamics, enabling the active maintenance of working memory while resisting distraction. Lastly, using an artificial neural network model, I demonstrated that the sparse implementation of temporally modulated working memory representations is preferred in recurrently connected neural populations such as the prefrontal cortex. In summary, this thesis provides a comprehensive investigation of higher cognition in higher-order brain regions, focusing on working memory tasks involving numerical stimuli. By examining neural population coding and unveiling sparse structures in the neuronal implementation of representations, our findings contribute to a deeper understanding of the mechanisms underlying working memory and higher cognitive functions

    The Making of Citizenship

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    Nach der UnabhĂ€ngigkeit Tansanias und Ugandas verhandelten lokale Akteure StaatsbĂŒrgerschaft neu. Als Außenseiter mussten die asiatischen Minderheiten Ostafrikas ihre Rolle in einer neuen Welt finden. Doch wĂ€hrend der 1960er verengten sich die sozialen und ökonomischen RĂ€ume fĂŒr sie, was letztlich in der Ausweisung der Asiaten aus Uganda gipfelte

    The role of nutritional status of soils from grassland and savanna ecosystems on the biochemical and physiological responses of Vigna unguiculata L. (Walp)

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    Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Most arable soils in sub–Saharan Africa savanna and grassland ecosystems are acidic and nutrient deficient with nitrogen and phosphorus being the most limiting and this poses a huge threat to agricultural productivity. To overcome soil nutrient deficiency and increase crop yields, farmers have resorted to high inputs of synthetic fertilizers, which are expensive and may cause environmental degradation. Use of legumes is an important alternative as they help enhance soil nutrition through biological nitrogen fixation. Vigna unguiculata L. (Walp), a highly nutritious legume crop that could be incorporated in small scale cropping systems to improve soil nutrition. However, there is limited information on the physiological and biochemical strategies enabling the growth of V. unguiculata under acidic and nutrient stress conditions. In this study it was hypothesized that symbiotic association between V. unguiculata and rhizospheric microbes affects the growth, nutrient assimilation and phytochemicals of the grain legume grown in nutrient stressed soils. Firstly, this study evaluated the physicochemical properties, microbial composition and soil enzymes activities of soils from four geographically distinct regions of KwaZulu-Natal representing savanna and grassland ecosystems. Secondly, the study investigated how the tripartite symbiosis of V. unguiculata, arbuscular mycorrhizal fungi and nodulating bacteria affect phosphorus and nitrogen nutrition, and the growth of V. unguiculata grown under acidic and nutrient stress conditions. Then, the study investigated how four V. unguiculata varieties regulated their phenolic acids and antioxidants to enhance their growth in acidic and nutrient stressed soils conditions. The four soil types were acidic with low mineral nutrients, with Bergville being the most acidic. The soils were significantly different in their physicochemical and microbial composition. Most bacterial strains identified in the soils belonged to genera Lysinibacillus, and Bacillus while the most identified fungal strains belonged to Fusarium and Trichoderma genera. There were variations in soil lignin degrading, C, N and P cycling enzyme activities. The identified soil enzymes included ÎČ-D Phosphatase, L-asparaginase, ÎČ-glucosaminidase, ÎČ-cellobioside, catalase and lacasse. The availability of this rich pool of soil microbes and soil enzymes is a great opportunity as these can be used to regulate nutrient cycling and enhance nutrient availability for crop production in the savanna and grassland ecosystems. Four V. unguiculata varieties (IT18, Batch white, Brown mix, Dr Saunders) were grown in these acidic and nutrient poor soils. These V. unguiculata varieties were nodulated by several bacterial strains including those of genera Bradyrhizobium, Rhizobium, Bacillus and Paenibacillus. The V. unguiculata fixed more than 60% of its total nitrogen from the atmosphere across all soil treatments. Interestingly, V. unguiculata plants which were nodulated by non-rhizobial bacteria strains effectively fixed significantly high amounts of atmospheric nitrogen. Vigna unguiculata also developed symbiotic association with arbuscular mycorrhizal fungi (AMF) as evidenced by high root mycorrhizal fungi colonization ranging from 58-100%. Variations were observed on growth kinetics, nutrient assimilation and utilization among the four V. unguiculata varieties. Vigna unguiculata was able to switch N source preferences utilizing both soil and atmospheric nitrogen. These findings revealed that V. unguiculata has the capacity to adapt to nutrient poor ecosystems by establishing symbiotic interaction with naturally occurring soil bacteria and AMF and through its ability to switch N source preferences; by using soil N and atmospheric N2 through biological nitrogen fixation. There were variations in the response of the four V. unguiculata varieties to different levels of soil acidity and nutrient stress with regards to phenolic acid concentration and antioxidant capacities. The most abundant phenolic acids were vanillic acid and protocatechuic acid and these constituted 22.59% and 17.22% respectively of the total phenolic acids in the plants. More so, there were differences in correlations between the phenolic acids and plant biomass, plant nutrition, soil nutrition and AMF infection. There was negative correlation between phenolic acids protocatechuic acid and syringic acid, and concentration of plant nutrients N and P. Varieties IT18 and Batch white had relatively lower concentrations of phenolic acids but these had the highest plant biomass. These results confirm that low phenolic acid concentrations have stimulatory effects on growth and nutrient uptake by plants while high concentrations may inhibit plant growth and development. There were variations among the V. unguiculata varieties with respect to oxygen radical absorbance capacity (ORAC) across the four soil types. Overall, the study demonstrated that V. unguiculata is adaptable to acidic and nutrient poor ecosystems as it has the capacity to regulate its phenolic acids which enhance nutrient uptake, promote legume-microbe symbiosis, and help scavenge radical oxidative species due to their antioxidant properties

    Proceedings of the 19th Sound and Music Computing Conference

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    Proceedings of the 19th Sound and Music Computing Conference - June 5-12, 2022 - Saint-Étienne (France). https://smc22.grame.f

    Study of Biodegradation and Bioremediation

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    Despite many years of efforts to reduce the emission of toxic pollutants into the environment, the contamination of air, soils and water by heavy metals and organic xenobiotics is still a serious problem. This has urged many scientists around the world to undertake research that aims to find effective methods of removing pollutants from the environment. Special attention is paid to biological methods, which, thanks to their numerous advantages, meet the expectations of the whole society. As part of the Special Issue “Study of Biodegradation and Bioremediation”, in the MDPI journal Processes, several valuable articles have been published, which together form a picture of the current state of advanced research on the effective fight against environmental pollution. These include papers on the biodegradation of petroleum compounds or synthetic dyes by microorganisms or the enzymes they produce. In addition, the Special Issue includes papers on the bioremediation of dangerous heavy metals such as mercury and copper, and the results make a valuable contribution to our current state of knowledge on this topic. A separate and valuable part of this collection of publications are review articles devoted to the remediation of antineoplastic drugs, as well as the hopes and challenges connected with the application of nanotechnology in bioremediation. We are pleased that so many researchers from different parts of the world have submitted their articles on this topic. We are very grateful to them. We hope that readers of this collection will find many interesting ideas and relevant information that will lead to new solutions in the bioremediation and biodegradation of emerging environmental contaminants. Prof. Ewa Kaczorek Dr. Wojciech SmuƂe
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