Les systèmes turbiditiques forment de grands édifices sédimentaires sous-marins situés au large des fleuves en pied de pente continentale et constituent les dépôts terrigènes les plus distaux d’un système fluviatile. Leur structure interne, définie comme un empilement de systèmes chenal-levées, montre des changements architecturaux au cours du temps dont les forçages sont encore mal connus, et le rôle respectif des facteurs de contrôle interne (lié au fonctionnement propre du système) ou externe (climat, variations du niveau marin, tectonique) reste sujet à débats. Afin de mieux comprendre le rôle de ces facteurs de contrôle, une étude détaillée de l’architecture du système Congo a été réalisée. Cette étude a été menée dans le cadre du projet de recherche Reprezaï (Ifremer/IUEM, depuis 2006), faisant suite aux projets Guiness et ZaïAngo (Ifremer/Total, 1992-2003), projets au cours desquels de nombreuses campagnes en mer ont permis l'acquisition d’une importante base de données géophysiques et géologiques. Une analyse quantitative de différents paramètres architecturaux des chenaux (longueur totale, longueur construite après avulsion, entre autres) de l’Edifice Axial du Congo (derniers 200 ka) révèle des cycles sédimentaires de progradation et rétrogradation des dépôt-centres, les plus grandes rétrogradations correspondant à des avulsions situées très en amont dans l’édifice turbiditique. Les dépôts-centres identifiés à la terminaison des chenaux correspondent à des complexes de lobes (selon la nomenclature de Prélat et al., 2009) relativement allongés dont les volumes (de 3 à 196 km3) varient considérablement dans le temps et l'espace sans pour autant montrer de cycles de variation comme pour les autres paramètres. Le volume cumulé de ces complexes de lobes reconnus représente jusqu'à 31% du volume de l’Edifice Axial. L’étude multiproxies (datations 14C, δ18O, mesures XRF, Carbone Organique Total, …) de carottes prélevées sur les chenaux les plus progradants et les plus rétrogradants, a fourni un cadre chronologique permettant de caler temporellement ces cycles sédimentaires. L’évolution temporelle des paramètres architecturaux a été comparée avec les variations des signaux paléoenvironnementaux et paléoclimatiques (pollens, COT, mesures XRF et MSCL, argiles…) enregistrés par une carotte de référence située en domaine hémipélagique et contemporaine de la construction de l’Edifice Axial. Les résultats mettent en évidence un lien étroit entre l’évolution architecturale de l’édifice turbiditique et les décharges fluviatiles du Congo. Ces dernières, mais aussi l’extension du couvert végétal sur le bassin versant, contrôlent le rapport sable/argile et donc, en partie, la capacité de transport des courants turbiditiques. Ces deux facteurs dépendent des précipitations liées aux variations d’intensité de la mousson en relation avec les cycles de précession (19-23 ka, Milankovitch). Un scénario de mise en place des systèmes chenal-levées et lobes de l’Edifice Axial en fonction des variations climatiques arides/humides sur le bassin versant a ainsi pu être proposé grâce à de bonnes contraintes stratigraphiques pour les derniers 40 ka. En période aride, les courants turbiditiques, peu fréquents et avec un fort rapport sable/argile qui diminue leur capacité de transport, sont propices à l'aggradation des chenaux, engendrant des conditions favorables pour la création ultérieure d’avulsions en amont. En période de transition aride/humide, lorsque le couvert végétal est encore peu développé, la décharge fluviatile accompagnée d’une charge solide importante augmente le volume des courants turbiditiques, favorisant les avulsions en amont du système. Enfin, les périodes humides, caractérisées par un débit liquide fort associé à une charge solide essentiellement argileuse qui décroît au fur et à mesure que le couvert végétal s’étend, génèrent des courants de turbidité dont la capacité de transport diminue au cours du temps […] / Turbidite systems are huge submarine sedimentary fans located off rivers, at the foot of the continental slope. They constitute the most distal terrigeneous deposits of a fluvial system. Their internal structure, defined as a stacking of channel-levee systems, show architectural changes through time. Forcing factors of these architectural changesare still poorly understood, and the respective role of internal (related to the own functioning of the system) or external forcing factors (climate, seal-level variations, tectonics) remains debated. To better understand the role of these controlling factors, a detailed study of the Congo system architecture was carried out. This study was conducted as part of the Reprezaï research project (Ifremer/IUEM, since 2006), following the Guiness and ZaïAngo projects (Ifremer/Total, 1992-2003), during which many oceanographic surveys allowed acquiring an important geophysical and geological data base. A quantitative analysis of different architectural parameters from the channels (e.g. total length, length built after avulsion,…) of the Congo Axial Fan (last 200 ka) reveals progradational-retrogradational sedimentary cycles of the depocenters, the highest retrogradations corresponding to avulsions located very upfan. Depocenters identified at the termination of the channels correspond to relatively elongated lobe complexes (according to the nomenclature of Prélat et al., 2009) with greatly variable volumes (from 3 to 196 km3) both in time and space, without any cyclicity like that identified by other parameters. The cumulative volume of these lobe complexes represents up to 31% of the Axial Fan volume. The multiproxies study (14C dating, δ18O, XRF measurements, Total Organic Carbon…) of cores sampled on the most prograding and retrograding channels provided a chronological framework to these sedimentary cycles. The temporal evolution of the architectural parameters was compared with changes in paleoenvironmental and paleoclimatic signals (pollens, TOC, XRF and MSCL measurements, clay mineralogy,…) recorded in the sediments of a reference core deposited simultaneously to the Axial Fan, but located outside the turbidite flows. Results highlight a strong link between the architectural evolution of the turbidite system and the Congo River discharge. These, as well as the expansion of the vegetation cover in the catchment area, control the sand/clay ratio and thus, at least partly, the transport capacity of turbidity currents that build the channel-levee systems. Both factors depend on rainfall related to the monsoon intensity variations in relation with precession (19-23 ka Milankovitch). A scenario for the deposition of channel-levee systems and lobes of the Axial Fan in link with arid/humid climate variations in the catchment area has been proposed thanks to good stratigraphic constraints for the last 40 ka. During arid periods, turbidity currents are infrequent and present a high sand/clay ratio which decreases their transport capacity. These turbidity currents are suitable to channel aggradation, generating favorable conditions for the subsequent creation of upfan avulsion. During periods of transition of arid to humid conditions, when the canopy is still underdeveloped, fluvial discharge and significant sediment load increases result in an increase of the turbidity currents volume, which favors upfan avulsions. Finally, during humid periods, Congo discharge is characterized by a strong liquid flow and a mainly clayey solid discharge which decreases gradually as the canopy extends. These conditions generate turbidity currents with decreasing transport capacity through time. However the transport capacity of these currents remains sufficient to reach distal portions of the systems and favor channels progradation. This climatic factor seems therefore to regularly disrupt the more perennial internal control which is also highlighted by the Congo Axial Fan architecture.

La marge de l’Algarve est un système contouritique principalement construit par l'action de la Veine d'Eau Méditerranéenne (MOW) et dont l'évolution est fortement influencée par les processus gravitaires, comme l'atteste les nombreux canyons et chenaux qui entaillent la pente continentale. A partir de l’analyse et de l’interprétation de données acoustiques haute résolution, cette thèse propose une reconstruction du fonctionnement du système contouritique de l’Algarve sur l’ensemble du Quaternaire. Ce travail améliore la compréhension des interactions existant entre les processus gravitaires et contouritiques ainsi que les connaissances concernant leurs facteurs de contrôle. Le schéma de circulation actuelle est conforme à la distribution des faciès sédimentaire et à l’architecture des drifts. La morphologie du fond marin, et notamment la présence de canyons, exercent un contrôle important sur l’orientation et l’intensité de la branche supérieure de la MOW (MUW). Les variations spatiales de la circulation océanique, comme celle induite par la capture du courant par un canyon, se traduisent directement par des différences géométriques et morphologiques au sein des dépôts sédimentaires. D’autre part, la présence de paléochenaux sous les drifts révèle l’existence d’un ancien système gravitaire fossilisé par la construction contouritique. La géométrie interne de ces paléochenaux montre que leur évolution temporelle est étroitement liée à l’interaction entre les écoulements gravitaires et l’hydrodynamique régionale. L’étude sismique met en évidence la présence de corps sédimentaires lenticulaires et sableux, intercalés dans les drifts et interprétés comme des « lobes perchés ». La granularité grossière de ces dépôts ainsi que leur fossilisation rapide et leur préservation par la croissance des drifts font de ces corps sédimentaires particuliers de potentiels réservoirs pour les hydrocarbures, et leur confère ainsi un intérêt industriel important. La mise en place des dépôts au cours des deux derniers millions d'années révèle que la construction de la marge de l’Algarve s’effectue sous l’action indépendante ou conjointe des processus gravitaires et des processus contouritiques. La sédimentation de cette marge est essentiellement contrôlée par les fluctuations climato-eustatiques : (1) en haut niveau marin relatif, les processus contouritiques dominent et les drifts croissent sous l’action d’une MUW intense; (2) en bas niveau marin relatif, la MUW est affaiblit et la croissance des drifts est réduite ; les processus gravitaires deviennent dominants et permettent la mise en place de lobes perchés sur la pente. / The Algarve Margin is a contourite system principally built under the action of the Mediterranean Outflow Water (MOW). The margin evolution is strongly influenced by gravity processes as attested by the presence of numerous canyons and channel that incise continental slope. Based on analysis and interpretation of high resolution acoustic data, this thesis proposes a reconstruction of sedimentary history of Algarve Margin during Quaternary. This work improves the understanding of the interactions existing between gravity processes and contourite processes, and their forcing parameters. The present circulation pattern reflects the sedimentary facies distribution and the drift geometry. The seafloor morphology and notably presence of canyons play an important role on the orientation and intensity of the MOW upper branch (MUW). Spatial variations of oceanic circulation, such as induced by current capture by a canyon, generate differences in geometry and morphology in sedimentary deposits. Furthermore, the presence of paleochannels under the drifts underlines the existence of ancient gravity system buried by contourite construction. The filling geometry of paleochannels shows that their temporal evolution is strongly linked to the interaction between gravity currents and regional hydrodynamics. Seismic data analyse emphasizes the presence of sandy lenticular sedimentary bodies intercalated in drifts. They are interpreted as “perched lobes”. Their sand content and their rapid fossilization and preservation by drift construction, confer them an important industrial interest. During the two last million years, sedimentary deposits show that Algarve Margin developed under the action of contourite processes, gravity processes and their interactions. On this margin, the sedimentation is principally controlled by climato-eustatic variations: (1) during high sea level, contourite processes are dominant and drifts grow under the influence of intense MUW; (2) during sea level lowstand MUW decrease and drifts growth decreases; gravity processes become dominant and generate the formation of perched lobes on the slope.

The experiment tested the hypothesis that the acetylcholine (ACh) release in the rat auditory cortex is greater in rats undergoing auditory classical conditioning compared to rats in a truly random control paradigm where no associative learning takes place and that this is mediated by prefrontal afferent projections influencing the nucleus basalis magnocellularis (NBM), which in turn modulates ACh release in neocortex. Rats with bilateral ibotenic acid lesions of medial prefrontal and agranular insular cortices were tested in an auditory classical conditioning task while ACh was collected from the primary auditory cortex. It was hypothesized that lesions of these prefrontal areas would prevent learning-related increases of ACh release in the primary auditory cortex. The hypothesized results were supported. Results from this experiment provide unique evidence that medial prefrontal cortex projections to the NBM are important for mediating cortical ACh release during associative learning.

Le langage est dans son ensemble bien préservé pendant le vieillissement (Meyer & Federmeier, 2010) tandis que la mémoire sémantique peut même s'améliorer (Kavé, Samuel-Enoch, & Adiv, 2009; Prinz, Bucher, & Marder, 2004; Salthouse, 2009; Verhaegen & Poncelet, 2013 ; Wingfield & Grossman, 2006), malgré de nombreux changements neurophysiologiques se produisant dans le cerveau (Grady, Springer, Hongwanishkul, McIntosh, & Winocur, 2006 ; Kemper & Anagnopoulos, 1989 ; Wingfield & Grossman, 2006). Cette thèse se concentre sur la préservation de la mémoire sémantique dans le vieillissement, « l'acte cognitif d'accéder aux connaissances stockées sur le monde » (Binder, Desai, Graves et Conant, 2009) à travers une tâche de jugement sémantique manipulant le contrôle sémantique avec deux niveaux de demande (faible et élevé) et deux types de relations sémantiques (taxonomique et thématique). Nous avons développé une nouvelle tâche variant les niveaux de demande (faible et élevé) chez 39 adultes jeunes et 39 adultes âgés. Plus précisément, les objectifs de notre étude étaient 1) d'identifier si le vieillissement affecte l'activité cérébrale liée à la mémoire sémantique conformément aux prédictions du modèle CRUNCH, à travers une tâche de jugement sémantique à deux niveaux d'exigences. 2) de combler le vide de la littérature sur l'existence et l'évolution des hubs sémantiques dans le vieillissement, à la lumière des théories single hub et dual-hub, en évaluant l'effet du vieillissement sur le rôle des lobes temporaux antérieurs (ATL) et du jonction temporo-pariétale (TPJ) en tant que représentations neuronales des centres sémantiques responsables respectivement du traitement taxonomique et thématique. Une soumission par rapport pré-enregistré (registered report) a été utilisée pour ce projet de recherche. Nos participants, adultes plus jeunes et plus âgés, étaient globalement appariés en termes de réserve cognitive, plus précisément en ce qui concerne le niveau d'éducation et comme le montrent les questionnaires évaluant l'engagement dans des activités cognitivement stimulantes, les tests MoCA et WAIS-III. Les résultats comportementaux ont confirmé que la tâche varie correctement la difficulté de la tâche puisque les taux d'erreur et les temps de réponse (RT) augmentent de manière linéaire avec l'augmentation des exigences de la tâche, à savoir dans la condition de forte demande. Nous avons constaté que la participation à des activités stimulantes sur le plan cognitif avait un impact positif à la fois sur les RT de référence et sur la précision. Nous n’avons pas observé de différence statistiquement significative dans la précision entre les participants jeunes et plus âgés, quelle que soit la condition. Nous avons constaté que des scores plus élevés aux tests WAIS-III et PPTT étaient positivement corrélés avec la précision chez les personnes âgées. En termes de RT, nous avons observé une différence statistiquement significative entre les participants jeunes et plus âgés pour la tâche et les conditions de référence, les adultes plus âgés étant plus lents à répondre en général. Les RT augmentent linéairement avec l'âge du participant. En tant que telle, la tâche de mémoire sémantique a réussi à a) manipuler la difficulté de la tâche sur deux niveaux d'exigences et b) démontrer une performance comportementale invariante selon l'âge pour le groupe plus âgé, comme l'exige le test du modèle CRUNCH (Fabiani, 2012 ; Schneider-Garces et al., 2010). Pour l'objectif n°1, les tests cruciaux du modèle CRUNCH, l'interaction IRMf groupe par difficulté, n'étaient pas cohérents avec les prédictions du modèle. Malgré nos résultats comportementaux, lorsque nous avons comparé directement la condition de faible demande avec la condition de forte demande, il n'y avait pas de différence statistiquement significative dans l'activation entre les conditions de faible et de forte demande. Nous n'avons pas non plus obtenu d'interaction entre tranche d'âge et difficulté. Nous avons obtenu des interactions significatives en comparant les conditions de demande faible et élevée avec la ligne de référence. Au niveau neuronal, indépendamment de l'âge, la tâche de jugement de similarité sémantique a activé un large réseau bilatéral fronto-temporo-pariétal. Pour l'objectif n°2 concernant l'effet de relation sémantique, le contraste de la condition taxonomique avec la condition thématique directement n'a pas trouvé d'activation robuste à un seuil corrigé. La condition taxonomique a donné des résultats intéressants par rapport à la condition de base. Sept groupes distincts dans le cortex fronto-temporo-pariétal ont été activés dans les deux hémisphères, y compris les lobes temporaux antérieurs (ATL) et la jonction temporo-pariétale gauche (TPJ). De plus, l'activation était significative dans le gyrus supérieur frontal gauche, le gyrus angulaire gauche (AG) et le gyrus frontal inférieur (partie orbitale) sur l'hémisphère droit. Cette découverte pourrait être en partie conforme à la théorie du double-hub, qui propose que les ATL bilatéralement et le TPJ agissent comme des hubs sémantiques. Bien que nous n'ayons pas trouvé d'activation significative dans les ATL pendant la condition taxonomique et dans le TPJ pendant la condition thématique, nous avons cependant constaté que dans la condition taxonomique parmi les sept clusters significativement activés, l'activation dans le gyrus frontal supérieur gauche était significativement corrélée avec la performance dans la condition taxonomique pour les deux groupes d'âge. L'activation dans le gyrus temporal moyen droit était également corrélée à l'amélioration des performances, mais cela n'était pas significatif dans le groupe plus âgé. En ce qui concerne la condition thématique, par contraste avec condition de référence, dix groupes distincts ont été activés, y compris la jonction temporo-pariétale (TPJ), alors que les ATL n'ont pas été activés de manière robuste pendant la condition thématique. Plus précisément, les régions activées comprenaient bilatéralement le gyrus angulaire, le gyrus temporal moyen, le gyrus frontal inférieur (partie triangulaire) et le gyrus frontal moyen. Nous visons à poursuivre des analyses supplémentaires pour explorer la relation entre les exigences de la tâche, le type de relation sémantique et la réorganisation neurofonctionnelle liée à l'âge. Cependant, ces résultats relatifs à la préservation avec l'âge des capacités à traiter les différentes relations sémantiques de mots sont associés à un certain nombre de réorganisations neurofonctionnelles. Celles-ci peuvent être spécifiques au traitement de différentes relations sémantiques et de différentes demandes de tâches. Il reste à déterminer si cette réorganisation est induite par les changements structurels du cerveau avec l'âge, ou par l'utilisation accrue de telles relations sémantiques tout au long de la trajectoire de la vie. / Language overall is well preserved in aging (Meyer & Federmeier, 2010) whereas semantic memory may even improve (Kavé, Samuel-Enoch, & Adiv, 2009; Prinz, Bucher, & Marder, 2004; Salthouse, 2009; Verhaegen & Poncelet, 2013; Wingfield & Grossman, 2006), despite numerous neurophysiological changes taking place in the brain (Grady, Springer, Hongwanishkul, McIntosh, & Winocur, 2006; Kemper & Anagnopoulos, 1989; Wingfield & Grossman, 2006). The present study focuses on the preservation of semantic memory in aging, the ‘cognitive act of accessing stored knowledge about the world’ (Binder, Desai, Graves, & Conant, 2009) by means of a semantic judgment task manipulating semantic control with two demand levels (low and high) and two types of semantic relations (taxonomic-thematic). We used a novel task that varied task demands (low versus high) in 39 younger and 39 older adults. More specifically, the aims of this study was 1) to identify whether aging affects the brain activity subserving semantic memory in accordance with the CRUNCH predictions, through a semantic judgment task with two levels of demands (low and high). 2) To bridge the gap in the literature on the existence and evolution of semantic hubs in aging, in light of the dual and single-hub theories, by evaluating the effect of aging on the role of the Anterior Temporal Lobes (ATLs) and the Temporo-parietal junction (TPJ) as neural representations of the semantic hubs responsible for taxonomic and thematic processing, respectively. A submission by registered report was opted for this research project. Our participants, younger and older adults, were overall matched in regards to level of education and as shown in questionnaires assessing engagement in cognitively stimulating activities, MoCA and WAIS-III tests. The behavioral results confirmed that the task was successful in manipulating task difficulty, with error rates and RTs increasing with increasing task demands, namely in the high-demand condition. We found that engaging in cognitively stimulating activities impacted positively on both baseline RTs and accuracy and that higher scores on the WAIS-III and the PPTT tests were positively correlated with accuracy in older adults. There was no statistical difference in accuracy between younger and older participants regardless of the condition, so there was no age effect in accuracy. In terms of RTs, there was a statistically significant difference between younger and older participants for both the task and the baseline conditions, with older adults being slower to respond in general. RTs increased the more the participant’s age increased, which is in line with findings in the literature. As such, the semantic memory task was successful in a) manipulating task difficulty across two levels of demands and b) demonstrating age-invariant behavioural performance for the older group, as requires to test the CRUNCH model (Fabiani, 2012; Schneider-Garces et al., 2010). For objective no 1, the crucial test of CRUNCH model, the fMRI age group by task demand interaction was not found. We did not find statistically significant interaction neither between task demands and age group for RTs or accuracy, nor in regards to brain activation. At the neural level, independently of age, the semantic similarity judgment task activated a large network including bilateral inferior frontal, parietal, supplementary motor, temporal and occipital brain regions, which correspond overall with the semantic network, as suggested in the literature. Region of interest analyses demonstrated task demand effect in these regions, most notably in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the pre-frontal gyrus, regions which are typically associated with semantic control requirements. We did not find any significant interactions between task demands and activation in the regions of interest either. Several possible reasons may justify the lack of findings as predicted by the CRUNCH hypothesis. For objective no 2 in regards to the semantic relation effect, the contrast of the taxonomic with the thematic condition directly did not produce any robust activation at a corrected threshold. The taxonomic condition yielded interesting results when contrasted with the baseline one. Seven distinct clusters in the fronto-temporo-parietal cortex were activated across the two hemispheres, including the anterior temporal lobes (ATLs) and the left temporo-parietal junction (TPJ). Additionally, activation was significant in the left frontal syperior gyrus, the left angular gyrus (AG) and the inferior frontal gyrus (orbital part) on the right hemisphere. This finding could be partly in line with the dual-hub theory, that proposes that the ATLs bilaterally and the TPJ act as semantic hubs. Though we did not find the expected double dissociation e.g., significant activation in the ATLs during the taxonomic condition only and in the TPJ during the thematic condition only, we found however that in the taxonomic condition among the seven significantly activated clusters, activation in the left superior frontal gyrus was significantly correlated with performance in both age groups. Activation in the right middle temporal gyrus was also correlated with improved performance, but this was not significant in the older group. During the thematic condition, when contrasted with baseline, ten distinct clusters were activated, including the temporo-parietal junction (TPJ), whereas the ATLs were not robustly activated during the thematic condition. We aim to pursue additional analyses to explore the relation between task demands, type of semantic relation and age-related neurofunctional reorganization. However, these results in relation to the preservation with age of the abiliites to process the different semantic word relations is associated with a number of neurofunctional reorganizations. These can be specific to the processing of different semantic relations and different task demands. Whether this reorganization is induced by the structural changes in the brain with age, or by the enhanced use of such semantic relations along the trajectory of life is still under exploration.

Individuals with attention deficit hyperactivity disorder (ADHD) with and without a learning disorder (LD) and a control group of clinically referred individuals with behavioral problems were compared on four neuropsychological tests of frontal lobe functioning. Test results were collected to examine if ADHD individuals with and without LD have deficits in frontal lobe functioning. Two age groups were used to examine developmental differences. In the six to ten age group there were 27 ADHD, 17 ADHD/LD and seven other clinically referred individuals. In the 11 -20 age group there were 12 ADHD, 23 ADHD/LD and 24 other clinically referred individuals. The ADHD and ADHD/LD groups performed at a lower level than the other diagnostic group on the freedom from distractibility factor of the WISC-R and the omission and commission errors of the Gordon Diagnostic system. Differences for the ADHD and ADHD/LD groups were also found on the number of correct responses for the Gordon Diagnostic system, the Speech Sounds test and the Seashore Rhythm test. The developmental differences that were found were not influenced by diagnosis. The deficits that the ADHD individuals with and without LD demonstrated were not affected by age.

Thesis (MSc (Earth Sciences))--University of Stellenbosch, 2009. / Fan 3 is one of four basin-floor fans that form part of the Tanqua Karoo Fan Complex in South Africa. It can be subdivided into several sandstone lobes, based on the presence of thin-bedded siltstone intervals above and below major sandstone packages. Six lobes are identified in the mid fan section, as well as two older groups of thin, low-volume turbidite deposits at the base. Some of the lobes are further divided into an upper and lower lobe-element based on depositional behaviour. The volumetrically and spatially larger lobes have a finger-like appearance in plan view, which is attributed to multiple lobe-scale axial zones. This is especially visible towards the eastern margins of Lobes 2, 4 and 5. The stratigraphy and facies distribution are presented on several 2D panels. Computer generated isopach maps are presented for each lobe, lobe-element and interlobe unit. Autogenic control on the depositional pattern of the Fan 3 lobe complex was inferred from the palaeoflow patterns of the composing lobes and lobe-elements. The majority of the lobes show a north-eastern palaeoflow direction in the south, with a gradual westward shift in the north. Inferred controls are basin-floor topography, the presence of pre-existing lobes, and characteristics of the depositional flow, such strength, density, sediment load, palaeoflow direction.

The hippocampal formation has been implicated in spatial formation for many decades. The hippocampus proper has received the most attention but other regions of the hippocampal formation contribute largely to spatial cognition. This thesis concentrated on one such region, the postsubiculum. The postsubiculum is considered important because it contains head direction cells and because it thought to be a major input to the hippocampus, via the entorhinal cortex. This thesis aims to test the functional role of the rat postsubiculum under two types of situation: one where the rat must rely on idiothetic cues for navigation, and another where the rat has visual cues present and can rely on these for orientation. The thesis also investigates hippocampal place cells and their stability over time after short exposures to novel environments. Chapter 3 of this thesis aimed to test whether the postsubiculum is necessary for path integration during a homing task. Rats were trained on a homing task on a circular platform maze. Once the task was acquired, rats were given lesions of the postsubiculum or sham lesions and then re-tested on the path integration task. The homing performance of rats with lesions of the postsubiculum was as good as that of the sham rats. A series of manipulations suggests that the rats were homing by path integration, confirmed by probe tests. The rats were then tested on a forced-choice delayed alternation T-maze task that revealed a significant impairment in alternation with delays of 5, 30, and 60 seconds. This suggests that the postsubiculum is not necessary for path integration in a homing task but is necessary for avoiding previously visited locations as is necessary in an alternation task. The experiments in Chapters 4 and 5 of this thesis aimed to investigate the effects of postsubiculum pharmacological inactivation on hippocampal CA1 place cells when rats were introduced to a novel environment with visual cues. A necessary first step was to assess place cells without any manipulation of the postsubiculum (Chapter 4) and then use information gained from this in the design of experiments in Chapter 5. Rats chronically implanted with recording electrodes in the CA1 region of the hippocampus were exposed to novel cue-rich environments whilst place fields were recorded. Following delays of 3, 6, or 24 hours, the same cells were recorded again in the same environment but with the cues rotated by 90°. Pixel-by-pixel correlations of the place fields show that stability of the place fields was significantly lower at 24 hours than at 3 hours. Stability after 6 hours was not significantly different from 3 hours. In the third set of experiments, rats were implanted with drug infusion cannulae in the postsubiculum and recording electrodes in CA1. Following infusions of either the AMPA receptor antagonist CXQX, the NMDA receptor antagonist D-AP5 or a control infusion of ACSF, place field stability was assessed as rats were exposed to a cylindrical environment with a single polarising cue card for 3 x 10 minute sessions and then again 6 hours later. There were no differences in place field correlations between the 3 drug conditions, although there was evidence of larger changes in spatial information content between cells in the CNQX and AP5 drug condition, but not the ACSF condition. The results suggest that, under the present testing conditions, place fields stability did not depend upon AMPA receptor-mediated transmission nor did it depend on NMDA receptor-mediated synaptic plasticity.

Orientador: Valéria Helena Alves Cagnon Quitete / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-11-05T17:40:47Z (GMT). No. of bitstreams: 1 Candido_EduardoMarcelo_D.pdf: 29056954 bytes, checksum: 56337986d8eaf83c84b1cf42b26d64df (MD5) Previous issue date: 2013 / Resumo: O objetivo do presente estudo foi caracterizar e comparar a estrutura e a biologia molecular dos receptores esteróides dos lobos prostáticos e da glândula de coagulação em ratos senis, submetidos a diferentes terapias hormonais exógenas, além de identificar os processos de proliferação e apoptose nesses órgãos. Trinta ratos da linhagem Sprague-Dawley com 10 meses de idade foram divididos em seis grupos experimentais e submetidos aos respectivos tratamentos: Grupo Senil/Controle (SC); Grupo Senil/Testosterona (ST); Grupo Senil/Estrógeno (SE); Grupo Castrado (CA); Grupo Castrado-Testosterona (CT); e Grupo Castrado-Estrógeno (CE). Após trinta dias de tratamento, os animais foram sacrificados e as amostras do lobo ventral (LV), lobo dorsal (LD) e glândula de coagulação (GC) foram coletados e processados para microscopia de luz, imunohistoquímica e Western Blotting. As concentrações séricas de hormônios esteróides em amostras sanguíneas também foram determinadas. Os resultados mostraram manutenção tecidual epitelial no LD e na GC após administração de testosterona (grupos ST). Já o LV apresentou espaçamento entre epitélio e estroma. Na administração de testosterona pós-castração (grupos CT), as respostas divergiram entre as glândulas analisadas. No LV tanto o epitélio quanto o estroma mantiveram-se alterados. O LD apresentou recuperação morfológica na comparação com o grupo CA. Já na GC, enquanto o epitélio mostrou sinais de recuperação, o estroma manteve características de hiperplasia e hipertrofia. A administração de estrógeno (grupos SE e CE) manteve ou pouco alterou a morfologia da GC, porém, provocou ampla desestruturação tecidual nos lobos ventral e dorsal, com geração de micro-ácinos, presença de NIPs e focos inflamatórios. A imunohistoquímica revelou diferenças quanto à imunorreatividade dos receptores androgênicos e estrogênicos em relação aos compartimentos epiteliais e estromal em todos os órgãos avaliados. O AR foi intensamente imunorreativo no epitélio dos lobos dorsal e ventral, situação oposta à observada nas glândulas de coagulação, onde o AR foi prevalentemente estromal. O ERa foi essencialmente estromal em todos os órgãos, enquanto que o ERb foi essencialmente encontrado no epitélio do lobo ventral e no estroma das glândulas de coagulação. No lobo dorsal, o ERb foi essencialmente estromal nos grupos SC e ST, com sua imunorreatividade alterando-se para epitelial nos grupos SE e CA, mostrando que esse receptor respondeu efetivamente à ação hormonal alterando sua localização. Assim, pode-se concluir que a terapia hormonal exógena, especialmente de testosterona, pode ser útil na manutenção tecidual prostática e que a imunorreatividade diferencial dos receptores hormonais pode sugerir uma forma lobo-específica de atuação dos hormônios sexuais na manutenção tecidual e promoção de patogênese prostática / Abstract: The aim of the present study was to characterize and compare the structure and the molecular biology of the steroid hormone receptors from prostatic lobes and coagulating gland in elderly rats submitted to different hormonal exogen therapies, besides identifying the apoptosis and proliferation processes in these organs. Thirty ten-month-old male rats were divided into six groups: Senile/Control group (SC); Senile/Testosterone group (ST); Senile/Estrogen group (SE); Castrated group (CA); Castrated-Testosterone group (CT); and Castrated-Estrogen group (CE). After 30-day treatment, the animals were sacrificed and the prostatic ventral lobe (VL), dorsal lobe (DL) and coagulating gland (CG) samples were collected and processed for light microscopy, immunohistochemistry and Western Blotting analyses. Serum steroid hormone concentrations in blood samples were also determined. The results showed epithelial tissue maintenance in DL and CG after testosterone administration (ST groups). However, the VL presented spacing between the epithelium and the stroma. After castration and testosterone administration, it was verified that both epithelium and stroma were changed in the VL. The DL showed morphological recovery in relation to the CA group. The CG showed signs of epithelial recovery in contrast to the glandular stroma, which maintained features of hyperplasia and hypertrophy. Estrogen administration (SE and CE groups) caused few changes in the CG morphology. However, the estrogen led to intense tissue disorganization in both VL and DL, showing microacini, prostatic intraepithelial neoplasia (PIN) and inflammatory foci. The immunohistochemical analysis showed intense AR immunoreactivity in the epithelium of the DL and VL, whereas AR immunoreaction was predominant in the stromal cells in the CG. ER? occurred preferentially in the stromal compartment in all the studied organs, while ER? was found preferentially in the VL epithelium and in the CG stroma. ER? immunoreactivity was predominantly stromal in the DL from SC and ST groups. In contrast, there was a change of the ER? reactivity to the epithelial cells in the DL from SE and CA groups. This fact showed that this hormone receptor actually was responsive to the hormonal action changing its localization. So, it could be concluded that hormonal exogen therapy, especially with testosterone, could be useful in prostatic tissue maintenance. In addition, the differential immunoreactivities of the hormonal receptors could suggest a lobe-specific way of action of the sex steroidal hormones in tissue maintenance and in the triggering of prostatic pathogenesis / Doutorado / Anatomia / Doutor em Biologia Celular e Estrutural

[pt] Correntes de turbidez são correntes gravitacionais turbulentas transportando grãos em alta velocidade e formando uma solução de água e sedimentos esparramados, sendo responsáveis pela formação de um tipo de reservatório petrolífero. O lobo turbidítico é um importante elemento arquitetural nos reservatórios turbidíticos e neste trabalho propomos uma modelagem assistida deste objeto, a partir de dados de pressão medidos durante um teste de formação. Para isto, foi desenvolvido um método de estimar as permeabilidades e parâmetros geométricos dos lobos com auxílio do simulador IMEX da CMG e da interpretação assistida do teste de formação simulado, utilizando como base os dados de pressão extraídos de testes de formação de referência. Na modelagem do lobo turbidítico incluímos a alocação de uma superfície de base. / [en] Turbidite currents are turbulent gravitational currents transporting grains in high speed creating a solution of water and dispersed sedments, being responsable for the formation of an oil reservoir. The turbidite lobe is an important architectural element for the turbidite reservoirs. In this work we propose an assisted modeling of this object based on measured well testing pressures. A method was developed to estimate permeabities and geometric parameters for this lobes using the IMEX fluid flow simulator and an assisted interpretation of the simulated well test comparing simulated pressures to those measured in a reference well test. In the modeling of the turbidite lobe, we allocate a base surface.

Cette thèse représente une étude pluridisciplinaire des dépôts actuels et anciens dans la<br />partie orientale du Golfe de Cadix afin d'améliorer la compréhension de la dynamique de la<br />MOW et de caractériser les forçages à l'origine des variations sédimentaires observées depuis<br />le Pléistocène terminal. Le schéma de circulation actuel est parfaitement conforme à la<br />distribution des faciès sédimentaires et montre l'omniprésence des cicatrices de glissement.<br />La morphologie du fond marin et la force de Coriolis exercent un contrôle important sur<br />l'orientation et l'intensité des différentes branches de la MOW. La diminution de la vitesse et<br />de la compétence de cet écoulement vers l'Ouest s'accompagne d'une diminution de la<br />granularité des dépôts. L'étude chronostratigraphique et sismique permet de contraindre dans<br />le temps et l'espace la mise en place des séquences contouritiques. Le climat est un facteur de<br />contrôle majeur de la sédimentation des 50 000 dernières années. Associées aux fluctuations<br />climatiques hautes fréquences, les variations glacio-eustatiques apparaissent responsables du<br />changement important des conditions de sédimentation mis en évidence dès l'entrée dans<br />l'interglaciaire actuel. Enfin, la mise en place polyphasée des systèmes chenal-lobes situés au<br />débouché des chenaux contouritiques montre l'interaction entre les processus contouritiques<br />et les processus gravitaires. L'activité de ces systèmes paraît contrôlée par la MOW, la<br />morphologie du fond et les changements climatiques ayant affecté le Quaternaire terminal.