The posterior parietal cortex (PPC) is a cortical region receiving inputs from different sensory modalities which has been shown to subserve a visuospatial function. The potential contribution of PPC in audiospatial behaviours and recognition of amodal spatial correspondences were postulated and assessed in the present study. Adult male Long- Evans rats received PPC lesions by aspiration, and they were compared to sham operated control rats on three behavioural tasks. In the Morris water maze, the rats had to learn to use the distal visual cues to locate an escape platform hidden in the pool. In an open field task, the rats were assessed on their reactions to a spatial relocation of a visual or an auditory object. In a spatial cross-modal transfer (CMT) task (Tees & Buhrmann, 1989), rats were trained to respond to light signals using spatial rules, and were then subjected to transfer tests using comparable sound signals. Results from the Morris water maze, the open field, and the initial training phase of the spatial CMT task confirmed a visuospatial deficit in PPC lesioned rats. However, if given sufficient training, PPC lesioned rats could learn the location of a hidden platform in the Morris water maze, and they could also acquire spatial rules in the CMT task. Such results indicated that the visuospatial deficits in PPC lesioned rats were less severe than previously thought. On the other hand, a persistent navigational difficulty characterized by a looping pattern of movement was observed in the PPC lesioned rats in the Morris water maze. Results from the open field indicated that PPC was less involved in audiospatial behaviours. Moreover, results also indicated that PPC was not necessary for spatial CMT. Hence, data from the present study did not support the idea that PPC played an essential role in supramodal spatial abilities in the rats. Instead, data from the spatial CMT task seemed to imply a role of PPC in managing conflicting spatial information coming from different sensory modalities.

During his twelve years of life, T., a gifted boy who was born with severe cerebral palsy, achieved the ability to communicate with "the rest of the world" at an advanced level, though he used facilitated and augmentative communication. The author of this narrative and interpretive study is T.'s father, who maintained a unique dialogue with his son. T. himself volunteered to contribute actively to the study by helping to plan and to edit, and by supplying a number of autobiographical sketches. The pedagogical relationship that existed between T. and his father is prominently featured. The study explores T.'s individual case through thirteen narrative "scenes" (beginning with his birth and ending with his twelfth year), which address various particulars of his lifeworld and his language development. Each narrative scene is followed by two, three, or four interpretive passages, each of which interprets one of seven themes that emerged from T.'s life. The seven themes are: memory, observation, scientific/technological assessment, not foreclosing on the future, integration, communication, and growth. The interpretive passages treat the seven themes at four levels of interpretation: the literal level, the moral level, the allegorical level, and the anagogic level. The attempt is to revive an exegetic practice common in the days before the Enlightenment, Cartesian doubt, and the "mathematical project" (Heidegger, 1993c, p. 293). Following the dictum that "the hermeneutic imagination is not limited in its conceptual resources to the texts of the hermeneutic tradition itself" (Smith, 1991, p. 201), the study borrows from a variety of sources, including Astrology, Waldorf education, and Zen. The reader is offered a direct experience of "the fecundity of the individual case" (Gadamer, cited in Jardine, 1994, p. 143). Emerging, through the thirteen scenes, the seven themes, and the four levels of interpretation, is a unique picture of an exceptional boy's language development.

Systems biologists use interaction graphs to model the behaviour of biological systems at the molecular level. In an iterative process, such biologists observe the reactions of living cells under various experimental conditions, view the results in the context of the interaction graph, and then propose changes to the graph model. These graphs represent dynamic knowledge of the biological system being studied and evolve as new insight is gained from the experimental data. While numerous graph layout and drawing packages are available, these tools did not fully meet the needs of our immunologist collaborators. In this thesis, we describe the data display needs of these immunologists and translate these needs into visual encoding decisions. These decisions led us to create Cerebral, a system that uses a biologically guided graph layout and incorporates experimental data directly into the graph display. Our graph layout algorithm uses simulated annealing with constraints, optimized with a uniform grid to have an expected runtime of o(E/V). Small multiple views of different experimental conditions and a measurement-driven parallel coordinates view enable correlations between experimental conditions to be analyzed at the same time that the measurements are viewed in the graph context. This combination of coordinated views allows the biologist to view the data from many different perspectives simultaneously. To illustrate the typical analysis tasks performed, we analyze two datasets using Cerebral. Based on feedback from our collaborators, we conclude that Cerebral is a valuable tool for analyzing experimental data in the context of an interaction graph model.

A persistent unanswered question in cognitive neuroscience has been what are the neural origins of human brain lateralization? Language is strongly lateralized to the left-hemisphere, however, lateralization varies with language experience. Bilinguals demonstrate a greater extent and variability of right-hemisphere involvement for language relative to monolinguals. Here, bilingualism is used as a lens into the conditions that drive brain lateralization. Why does bilingual language processing yields more robust bilateral neural activation relative to monolingual language processing? Neural activation and functional connectivity were measured to test hypotheses about the temporal dynamics of hemispheric recruitment during language processing in monolingual and bilingual children with varying ages of first bilingual language exposure. Hypothesis (1), The human brain is strongly left-hemisphere lateralized for language, but, when faced with the demands of two languages, additional right-hemisphere resources are recruited. Hypothesis (2), The human brain has the potential for enhanced dual hemispheric language processing that can be either potentiated or not based on early life bilingual versus monolingual language experience. If dual language experience places increased cognitive demands on the bilingual brain requiring additional right-hemisphere resources, asynchronous neural activation in left and right hemispheres was predicted. If dual language experience potentiates dual hemispheric language processing, synchronous neural activation in left and right hemispheres was predicted. Furthermore, only early-exposed bilinguals but not later-exposed bilinguals or monolinguals, would show synchronous neural activation across the hemispheres. Early experience with one language (monolinguals) or two languages at different times during a child's development (early-exposed bilinguals, later-exposed bilinguals) revealed differences in the time-course of activation across the two hemispheres' language areas, supporting Hypothesis (2). Monolinguals and later-exposed bilinguals showed asynchronous activation between the hemispheres. Early-exposed bilinguals showed synchronous activation between the hemispheres. The results provide a new view on how different experiences can drive lateralization in development and reveal the neural basis of bilateral activation in the bilingual brain. Synchronous temporal accessing of the hemispheres in bilinguals suggests early life bilingual language experience may support more equal and efficient hemispheric involvement, and, in turn, constitute the brain-based mechanism that makes possible the widely observed linguistic and cognitive advantages in young bilinguals.

La investigación pertenece al paradigma sociocrítico y abordaje de investigación acción participación OPS (1999), tuvo como objetivos: conocer, analizar y modificar el afrontamiento de las madres con hijos que padecen parálisis cerebral en la Clínica San Juan de Dios. El referencial teórico estuvo sustentado en los conceptos de afrontamiento de madres, Badia (2009), parálisis cerebral infantil, NINDES (2007) y modelo de atención de Callista Roy, Marriner (1999); los sujetos de investigación fueron 9 madres con niños entre 2 a 5 años de edad, que padecen parálisis cerebral de tipo espástica. La técnica de recolección de datos fue la entrevista semiestructurada, la muestra se obtuvo por saturación recolectándose datos antes y después de la intervención, luego se utilizó el análisis de contenido temático. Se tomó en cuenta los criterios de rigor científico y ético. Surgieron 3 categorías: De la incapacidad de afrontar de la enfermedad a afrontar los conflictos externos e internos a través del amor maternal y la fe en Dios, De las secuelas físicas propias de la enfermedad a mejorar la calidad de vida de los niños con parálisis cerebral infantil y como último Del abandono paterno al apoyo familiar en el cuidado compartido de un niño con parálisis cerebral infantil; cada una de ellas respectivamente analizadas y confrontadas de acuerdo a la realidad vivida. Finalmente, con el Programa Educativo “Afrontando Nuevos Desafíos” se logró, que muchas de las madres, alcancen condiciones satisfactorias que conlleven a un cuidado de calidad en su hijo con parálisis cerebral infantil.

The cerebral tissue requires a constant supply of oxygen and nutrients. This is maintained through delivering a constant supply of blood. The delivery of sufficient blood is preserved by the cerebral vasculature and its autoregulatory function. The cerebral vasculature is composed of the Circle of Willis (CoW), a ring-like anastomoses of arteries at the base of the brain, and its peripheral arteries. However, only 50% of the population have a classical complete CoW network. This implies that the route of blood flow through the cerebral vasculature is different and dependent on where the blood is needed most in the brain. Autoregulation is a mechanism held by the peripheral arteries and arterioles downstream of the CoW. It ensures the delivery of the essential amount of cerebral blood flow despite changes in the arterial perfusion pressure, through the vasoconstriction and vasodilation of the vessels. The mechanisms that control the vessels’ vasomotion could be attributed to myogenic, metabolic, neurogenic regulation or a combination of all three. However, the variations in the CoW structure, combined with different pathological conditions such as hypertension, a stenosis or an occlusion in one or more of the supplying cerebral arteries may alter, damage or abolish autoregulation, and consequently result in a stroke. Stroke is the most common cerebrovascular disease that affects millions of people in the world every year. Therefore, it is essential to understand the cerebral hemodynamics via mathematical modelling of the cerebral vasculature and its regulation mechanisms. This thesis presents the developed model of the cerebral vasculature coupled with the different forms of autoregulation mechanisms. The model was developed over multiple stages. First, a linear model of the CoW was developed, where the peripheral vessels downstream of the CoW efferent arteries are represented as lumped parameter variable resistances. The autoregulation function in the efferent arteries was modelled using a PI controller, and a metabolic model was added to the lumped peripheral variable resistances. The model was then modified so the pressure losses encountered at the CoW bifurcations, and the vessels’ tortuosity are taken into account resulting in a non-linear system. A number of cerebral autoregulation models exist in the literature, however, no model combines a fully populated arterial tree with dynamic autoregulation. The final model presented in this thesis was built by creating an asymmetric binary arterial vascular tree to replace the lumped resistance parameters for the vasculature network downstream of each of the CoW efferent arteries. The autoregulation function was introduced to the binary arterial tree by implementing the myogenic and metabolic mechanisms which are active in the small arteries and arterioles of the binary arterial tree. The myogenic and metabolic regulation mechanisms were both tested in the model. The results indicate that because of the low pressures experienced by the arterioles downstream of the arterial tree, the myogenic mechanism, which is hypothesised by multiple researchers as the main driver of autoregulation, does not provide enough regulation of the arterioles’ diameters to support autoregulation. The metabolic model showed that it can provide sufficient changes in the arterioles’ diameters, which produces a vascular resistance that support the constancy of the autoregulation function. The work carried out for this research has the potential of being a significant clinical tool to evaluate patient-specific cases when combined with the graphical user interfaces provided. The research and modelling performed was done as part of the Brain Group of the Centre of Bioengineering at the University of Canterbury.

This study investigated the effects of interference from a center stimulus on the recognition of faces presented in each visual half-field using the tachistoscoptic presentation. Based on prior studies, it was hypothesized that faces would be recognized nnre accurately based on outline features when presented to the Left visual field - Right hemisphere and on inner features for the Right visual field - Left hemisphere. It was also hypothesized that digits presented at center fixation would interfere most with the recognition of the inner details of faces presented to the right hemisphere, since recognizing both faces and digits requires high-frequency spectral analysis (Sergent, 1982b).Each stimulus was cinposed of either a number or a blank at center fixation and a face placed either to the left or right of fixation. The results indicated no performance differences due to the visual field of presentation. Recognition was most accurate when no center stimulus was present, and recognition of outer details was more accurate than recognition of inner details. Subjects tended to use top-to--bottan processing for faces in both visual fields.

This study investigated the hypothesis that bilateral stimulation of the cortex would facil_tate the performance of a letter matching task as compared to unilateral stimulation.Furthermore, the study expected to observe a RVH superiority for a NI letter match and a LVH superiority for making a PI letter match as observed in an earlier study (Cohen, 1972). These results were not found. The only conclusive result found was that the NI letter match was a more difficult match to make than any of .he other letter matches. Possible sources for this factcr were discussed.

No description available.

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.