The basal ganglia are a dynamic neural network of telencephalic subcortical nuclei, involved in adaptive control of behaviour. There has been much experimental evidence on the anatomy and physiology of the basal ganglia published over the last 25 years showing that the basal ganglia are involved in the learning of many adaptive behaviours, including motor planning, working memory and cognitive functions. Current qualitative basal ganglia models of the box and arrow type, whilst explaining much of the anatomical data, do not give enough insight into the mechanisms involved in basal ganglia function either in health or in disease states. The striatum is the main input nucleus of the basal ganglia, integrating widespread cortical and thalamic inputs to perform behaviour selection. Convergent data from control theory learning models and experimental data have shown that the phasic dopamine signal in the striatum could be performing a similar function to a scalar teaching signal in reinforcement learning models, both signals indicating the occurrence of reward. Similarly, both models and electrophysiological data have shown how the timing of this reward signal can be changed during learning so as to occur at the point in time of the earliest predictor of forthcoming reward. These models do not, however, show how this teaching signal is used in the striatum to learn to select the action most likely to lead to reward. Computational models have been produced to investigate the circuitry involved in striatal action selection. These models have tended to be of winner-takes-all networks, using a mechanism of recurrent lateral inhibition between the medium spiny cells of the striatum to select the winner and thus releasing the behavioural action judged to be correct in the current environmental context. However, the necessary biological circuitry to implement a winner-takes-all network is absent in the striatum. This leads to a requirement for new models of striatal function incorporating current biological data to provide a more realistic mechanism for behavioural selection. This thesis develops a biophysically inspired, minimal current model of a striatal medium spiny neuron which utilises transitions between two membrane potential states, both below firing threshold, to filter excitatory input. The behaviour of the model is first validated against experimental electrophysiological data and then used to demonstrate how the striatum could perform two of the tasks required for behaviour selection; accurately timed release of behaviours and learning a sequence of action selections to obtain reward. In the first series of simulations timed release of behaviours is demonstrated to be linearly related to the timing of firing of feed forward inhibitory interneurons. In a second set of simulations learned sequences of action selection, using a simulated dopamine reward signal, are shown in a reward location task performed by a small network of model medium spiny striatal neurons. Taken together these studies show that this simple model of a striatal medium spiny neuron is capable of simulating the basic functionality required for behaviour selection in a manner which has greater biological plausibility than previously published models.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Designing a mechanistic model that can give rise to realistic architecture of ecological networks is central to the understanding of how species assemble and function in ecosystems. As species are constantly adjusting their diets in an antagonistic network, we here incorporate this adaptive behaviour of diet choice into a bipartite network model, with the effect of antagonistic interactions between species depicted by Holling’s type II functional response. Predictions of this model fit extremely well with the observed levels of nestedness, modularity and node-degree distributions for 61 real host-parasitoid and plant-herbivore networks. We further examined two specific scenarios of our model (species with identical [neutral] demographic parameters and interactions with identical [neutral] benefit in the network) and found that the demography-neutral scenario overestimated observed modularity, whilst the benefit-neutral scenario over-estimate observed nestedness. Relationships between nestedness, modularity and connectance were found strong. Moreover, in contrast to the common belief of the high modularity in antagonistic networks, most real networks (> 80%) are significantly nested, whilst nearly 40% of the real networks are surprisingly less compartmentalized than random networks generated from null models. Regardless of the controversy on whether antagonistic networks are nested or compartmentalized, the proposed model captured the essence of the dynamic nature of structural emergence in antagonistic networks. Due to its predictive power, this model was further used to investigate robustness in antagonistic networks. Predictions showed that the robustness of a network is determined by many factors, such as connectance, resource degree distribution, resource-consumer ratio, diversity, nestedness and compartmentalisation. Surprisingly, the manner of network response to species loss was independent of the sequence followed while removing species from a network. Variations were only noticed in the intensity of the effect resulting from the removals. In addition, we also showed that species extinction procedures which ignore the interaction switch underestimate the effect of any loss of species in these networks. We must therefore value our knowledge of possible adaptive processes in the ecosystem as they may be important for resolving the diversity-stability debate. / AFRIKAANSE OPSOMMING: Die ontwerp van ’n meganistiese model wat aanleiding kan gee tot realistiese argitektuur van ekologiese netwerke is sentraal tot die begrip van hoe spesies bymekaar kom en funksioneer in ekosisteme. Soos spesies voortdurend hul dieet aanpas in ’n antagonistiese netwerk, het ons hierdie aanpasbare gedrag van dieet keuse in ’n bipartiet netwerk model ingewerk, met die effek van antagonistiese interaksies tussen spesies wat uitgebeeld word deur Holling se tipe II funksionele reaksie. Voorspellings van hierdie model pas baie goed met die waargenome vlakke van nestedness, modulariteit en node-graad uitkerings vir 61 ware gasheer-parasiet en plant-herbivoor netwerke. Verder het ons twee spesifieke gevalle van ons model (spesies met identiese [neutrale] demografiese parameters en interaksies met identiese [neutrale] voordeel in die netwerk) ondersoek en gevind dat die demografie-neutrale geval waargenome modulariteit oorskat, terwyl die voordeelneutraal geval waargenome nestedness oorskat. Verhoudings tussen nestedness, modulariteit en konnektiwiteit is sterk bevind. Verder, in teenstelling met die algemene verwagting van hoe modulariteit in antagonistiese netwerke, is oorhoofse werklike netwerke (> 80%) aansienlik geneste, terwyl byna 40% van die werklike netwerke is verbasend minder gekompartimenteerd as ewekansige netwerke gegenereer uit null modelle. Ongeag van die omstredenheid oor of antagonistiese netwerke geneste of gekompartimenteerd is, die voorgestelde model vang die essensie van die dinamiese aard van die strukturele opkoms in antagonistiese netwerke. As gevolg van sy voorspellende krag, is hierdie model verder gebruik om robuustheid te ondersoek in antagonistiese netwerke. Voorspellings het getoon dat die robuustheid van ’n netwerk word bepaal deur verskeie faktore, soos konnektiwiteit, hulpbron-graad verspreiding, hulpbron-verbruiker verhouding, diversiteit, nestedness en kompartementasie. Verrassend, die wyse van die netwerk reaksie op die verlies van spesies was onafhanklik van die reeks wat gevolg het toe die spesies verwyder is uit ’n netwerk. Variasies is slegs opgemerk in die intensiteit van die effek van die verskuiwings. Benewens, ons het ook aangetoon dat die prosedures van spesies se uitsterwing wat die interaksie skakelaar geignoreer het, onderskat die effek van ’n verlies van spesies in hierdie netwerke. Ons moet dus die waarde van ons kennis van die moontlike aanpassing prosesse in die ekosisteem in agneem, aangesien dit belangrik kan wees vir die oplossing van die diversiteit-stabiliteit debat.

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In line with the Vulnerability-Stress-Adaptation (VSA) model of marriage, this study examined the role of neuroticism, stressful life events, mutual problem solving and negative relationship attributions on marital quality and adjustment among a sample of newlywed couples in Addis Ababa. A quantitative cross-sectional study design involving a sample of 192 newlywed couples was employed. Data were analysed using correlation and multiple regression analysis methods. The PROCESS module in SPSS and Structural Equation Modeling was also used to test indirect effects and actor and partner effects, respectively. The results showed that for both wives’ and husbands’, neuroticism significantly predicted their own marital satisfaction but only husbands’ neuroticism significantly predicted their partners’ marital satisfaction. Stressful life events did not have a significant actor and partner effect for both wives’ and husbands’. Negative relationship attribution was found to be a significant predictor of actors as well as partners' marital satisfaction for both wives’ and husbands’ while only husbands’ mutual problem solving, not that of wives’, had a significant effect on their own marital satisfaction. Tests of indirect effects also showed that, for both wives’ and husbands’, neuroticism had a significant negative intrapersonal and interpersonal indirect effect on marital satisfaction through the mediation of both mutual problem solving and negative relationship attribution. Wives’ and husbands’ stressful life events had a significant negative intrapersonal and interpersonal indirect effect on marital satisfaction through the mediation of negative relationship attribution. Mutual problem solving only mediated a significant indirect effect of husbands’ stress on marital satisfaction at the intrapersonal level and wives’ stress on marital satisfaction at the interpersonal level. This research contributed to enhancing scientific knowledge that guides the design and implementation of policies, programs, and services to promote newlyweds’ marital quality and adjustment in the Ethiopian context. The research also made a theoretical contribution to the VSA model by indicating that adaptive processes play a varying mediational role for wives’ and husbands’ in the indirect effect of stress on marital satisfaction and by confirming that adaptive processes such as mutual problem solving and negative relationship attribution play a more prominent role in affecting marital quality and satisfaction than the other two components of the model, that is neuroticism and stressful life events. / Psychology

Made available in DSpace on 2014-07-29T15:22:31Z (GMT). No. of bitstreams: 1 Dissertacao parte 1 Murilo Luiz Ferreira.pdf: 7820233 bytes, checksum: c6c5eeaea4a922931faefa4be4ed460c (MD5) Previous issue date: 2011-04-19 / To tell stories is part of the essence of human beings. Since our earliest ancestors we have been involved by several narratives - oral, written or broadcasted. With the changes raised by the Gutenberg Galaxy, narratives gained more visibility in the art of storytelling, especially in literature. Since the 1950's that television is replacing printed texts, using audio and image together to further engage human beings in the real and fictional narratives. And this thesis is based on the search of elements of approximation and divergence between literature and television, having as object of study the novel written by Dinah Silveira de Queiroz, A Muralha, originally published in 1954, and the homonymous adaptation as a television series produced by TV Globo in 2000. The methodology includes the analysis of the relationships between literary and television studies by the perspective of cultural studies and cultural media, focusing particularly on the features of each of these media,looking for theoretical backgrounds that support the hypothesis of this research. As narrative is the main concern of this thesis, theories and analysis of focalization, space, time and characters became extremely important, as well the reflections about the three perspectives of adaptation and the four adaptive processes, which are: addition, reduction, displacement and transformation. This study lead us to conclude that as much as literature and television give evidences to prove the uniqueness of each of these artistic expressions, they contain similar and important elements that support the art of turning words into images. / Contar história é parte da essência do homem. Desde os nossos ancestrais mais remotos, estamos envolvidos com diversas narrativas orais, escritas, audiovisuais. Com as transformações surgidas com a Galáxia de Gutenberg, as narrativas escritas ganharam grande destaque na arte de narrar, principalmente com a literatura. A partir da década de 1950, a televisão passa a ocupar o lugar dos textos impressos, utilizando da junção do áudio com a imagem para envolver ainda mais o homem nas narrativas reais e ficcionais. E é na busca pelos elementos de aproximação e divergência entre literatura e televisão que este trabalho se baseia, tendo como objeto de estudo o romance de Dinah Silveira de Queiroz, A Muralha, publicado inicialmente no ano de 1954, e a adaptação homônima feita pela Rede Globo em formato de minissérie, no ano 2000. Os caminhos percorridos são as relações entre os estudos literários e televisivos com os estudos culturais e a cultura da mídia, passando pelos entremeios de cada uma dessas mídias, na busca por embasamento teórico-metodológico que corroborassem as hipóteses levantadas. Como a narrativa é o principal foco deste trabalho, as teorias e análises sobre focalização, espaço, tempo e personagens foram de extrema importância, assim como as reflexões sobre as três perspectivas de uma adaptação e os quatro processos adaptativos adição, redução, deslocamento, transformação. Esses caminhos nos levaram a concluir que, por mais que literatura e televisão apresentem elementos que comprovem a singularidade de cada uma dessas expressões artísticas, elas contêm elementos semelhantes e importantes que auxiliam no desenvolvimento da arte de transformar palavras em imagens.

Dans un contexte environnemental anthropisé, fragmenté et soumis à un changement climatique rapide, l’appréhension des processus d'adaptation locale des organismes marins par l'étude de zones de contact entre taxa proches constitue une approche privilégiée. Dans ces zones, des génotypes hybrides persistent malgré un état de maladaptation liée à des incompatibilités génétiques endogènes et/ou des barrières exogènes. L'histoire biogéographique complexe de la telline baltique Macoma balthica fait émerger quatre zones hybrides européennes, dont l'une, localisée autour de la Pointe Finistère (France), est le résultat d’un contact entre deux stocks génétiques ayant divergé en allopatrie. Ces divergences sont susceptibles de rompre la coadaptation entre génomes nucléaire et mitochondrial en raison de l'émergence d'incompatibilités mitonucléaires (MNIs). Ainsi, les sous-unités protéiques des cinq complexes de la chaine OXPHO sont codées à la fois par des gènes nucléaires et mitochondriaux, et une coévolution inter-génomique étroite est requise pour maintenir la production énergétique cellulaire. De précédentes données de transcriptomique dévoilent de probables MNIs chez M. balthica au niveau des complexes respiratoires I et V. Afin d’apporter des éléments de compréhension aux mécanismes de maintien des zones hybrides dans un contexte de pression anthropique, le présent travail se propose de tester l'hypothèse de putatives MNIs dans cette zone de contact. Pour cela, (i) six mitogénomes correspondant à cinq lignées haplotypiques divergentes en Europe ont été séquencés et l'architecture génomique a été étudiée conjointement à une cartographie des mutations des 13 gènes mitochondriaux, (ii) le niveau de transcription de 5 gènes nucléaires et 8 gènes mitochondriaux (complexe I à V) des individus hybrides a été comparé à celui des lignées parentales après détermination du statut d'hybridation de chaque individu (six populations françaises). A défaut d'apporter des éléments de réponses concrets quant à l'existence de MNIs chez M. balthica, et ses répercussions évolutives en terme de dépression d'hybridation, ce travail constitue un tremplin vers une étude approfondie de la zone hybride française en développant de nouveaux outils moléculaires, et de solides techniques expérimentales pour la conduite de futurs croisements artificiels. / In the anthropized, fragmented environmental context subject to rapid climate change, understand local adaptation processes of marine organisms by studying the contact zones between close taxa is a preferred approach. In these areas, hybrid genotypes persist despite a maladaptive state related to endogenous genetic incompatibilities and/or exogenous barrier. The complex biogeographic history of the Baltic tellin Macoma balthica leads to emergence of several European hybrid zones, one of which, located around the Pointe Finistère (France), is the result of the confluence of two genetic stocks that have diverged in allopatric. These divergences may have lead to the co-adaptation breakdown between nuclear and mitochondrial genomes due to the emergence of mito-nuclear incompatibilities (MNIs). Thus, the different protein subunits of the five OXPHO chain complexes are encoded by both nuclear and mitochondrial genes, and a tight inter-genomic coevolution is required to maintain the cellular energy production. Recent transcriptomic data unveil the existence of underlying MNIs in M. balthica, bearing by the respiratory complexes I and V. In order to provide some understanding clues of mechanisms in hybrid zone's maintenance in the context of human pressure, the present work aims to test the assumption of putative MNIs in this area. For this purpose, (i) six mitogenomes corresponding to five divergent haplotype lineages in Europe were sequenced and the genomic architecture has been studied jointly to a mapping mutation of the 13 mitochondrial genes, (ii) the level of transcription of 5 nuclear and 8 mitochondrial genes (complex I to V) of hybrid individuals was compared to the parental lineages after identification of the hybrid status of each individual (six french populations). For the lack of bringing concrete answers concerning the existence of MNIs in M. balthica, and its evolutionary effects in term of hybrid breakdown, this work is a springboard for a comprehensive study of the French hybrid zone by developing new molecular tools, and stable experimental technics for the realisation of future artificial crosses.

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