Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / Not embargoed. Vita. Bibliography: 207-220.

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2005. / On campus access only. Vita. Bibliography: 124-141.

Thesis advisor: Elizabeth Altmaier, Daniel Tranel. Includes bibliographic references (p. 142-155).

Thesis (Ph.D.)--Fairleigh Dickinson University, 1998. / Source: Dissertation Abstracts International, Volume: 59-10, Section: B, page: 5592. Chairperson: Neil A. Massoth. Includes bibliographical references (leaves [99]-111).

Disputats, Umeå universitet, 2006. / Härtill 3 uppsatser.

Five experiments were carried out to discover whether there is a subjective enhancement of temporal contours analogous to the Mach band effects in spatial vision. A transient overshoot in the incremental threshold occurred immediately after the crest of rising linear ramps at photopic levels. A psychophysical matching experiment verified that this peaking effect is perceived as a bright pulse and can be considered the temporal equivalent of the bright Mach band. No equivalent of the dark Mach band at the foot of rising linear ramps was found. Rather there was an anticipatory decrease of sensitivity (Crawford effect) at the base of ascending gradients. The magnitude of this effect was directly proportional to the rate of change of the stimulus at photopic levels. Data from descending ramps was less simple to interpret. A small rise in incremental threshold was sometimes observed at the crest of ramps, but this effect was much less pronounced than the peak at the crest of equivalent ascending ramps. Matching procedures located troughs at the foot of descending ramps which correspond to the dark spatial Mach band. This effect was less apparent when incremental threshold techniques were employed. An experiment using exponential rather than linear change in luminance over time gave results in general accord with the above. The Crawford effect was found to follow the Bunsen-Roscoe Law. It was found that the transient undershoot and overshoot effects were related to the rate of change rather than the actual form of the ramp when the rate of change was greater than about 300mL per second. Impulse responses were derived by differentiating step responses. Ascending steps generated a biphasic impulse response and descending steps give a triphasic unit impulse response. This lack of equivalence over conditions is diagnostic of system nonlinearity. Fourier analysis of the impulse responses showed equivalent spectral components and lowpass filter action in each case, indicating change in gain and phasing rather than time constants occur between 'on' and 'off' conditions. The system was shown to be quasilinear within conditions since linear convolution of the impulse responses with appropriate ramps generated functions that were a fair approximation to the psychophysical response to such ramps. The relationship between the impulse response and the spatial equivalent line spread function was discussed and the similarity of the impulse responses to dynamic changes in sensitivity inferred from results of masking experiments pointed out. The results were then considered in relation to a multichannel model for processing spatiotemporal information.

Working memory is involved in a variety of cognitive tasks, with working memory capacity predicting an individual's ability to process information and focus attention on taskrelated information. Subsequently, recent research has investigated whether working memory capacity can be improved through training and whether improvements generalise to other cognitive, behavioural or emotional domains. This training is typically adaptive in nature, changing in difficulty according to participant ability, and can be completed in the participant's home on a computer, giving it the potential to be an easily accessible intervention for a range of clinical populations. The first paper presents a systematic review evaluating the effectiveness of computerised working memory training for individuals with neurodevelopmental disorders, which are often associated with working memory difficulties. The review found that to date, working memory training has been investigated in four neurodevelopmental disorders: attention deficit/hyperactivity disorder; autism spectrum disorder; intellectual disability and specific learning disorder. The findings indicate that although training appears to produce short-term improvements in the working memory capacity, this does not reliably generalise to other cognitive processes or disorder-specific symptoms. The second paper presents a randomised controlled trial investigating the effects of working memory training for reducing worry in high-worriers. Working memory capacity limitations, and subsequent difficulties in attentional control, are believed to be central to the maintenance of worry. Participants were randomly assigned to complete 15 days of nonadaptive working memory training using a 1-back task, or adaptive working memory training using a n-back task. Training led to improvements in working memory capacity and worry symptoms post-training and at four-week follow-up, with improvements on the adaptive training task significantly correlating with improvements in working memory capacity and worry. These findings are discussed in terms of implications for clinical practice and future research, together with the limitations of the study.

To be accepted into social groups, individuals must internalise and reproduce appropriate group conventions, such as rituals. The high fidelity copying of such rigid and socially stipulated behavioural sequences places heavy demands on executive function abilities. Given previous research showing that challenging executive functioning also improves it, it was hypothesised that prolonged engagement in ritualistic behaviours would improve executive functioning in children, in turn improving their ability to delay gratification. A three month circle-time-games intervention with primary school children in two contrasting cultural environments (Slovakia and Vanuatu) was conducted. In both environments we found the intervention improved children's executive function and in turn their ability to delay gratification. Moreover, these effects were amplified when the intervention task was imbued with ritual, rather than instrumental, cues. The findings presented in this thesis have potentially far-reaching implications for child-rearing and educational practices, suggesting ritual participation may be necessary for the cultivation of future mindedness.

The aim of this thesis was to investigate the neural underpinnings of persistent developmental stuttering. We explored neural systems important for speech-motor integration and focused on subcortical control systems: the basal ganglia and cerebellum. A secondary aim of this work was to distinguish effects related to general traits of the disorder from those reflecting specific states of stuttered speech. To address these aims we used a variety of neuroimaging methodologies as well as an extensive neuropsychological and empirical test battery. Our examination of neural pathway microstructure using diffusion-tensor imaging replicated previous findings of widespread disorganisation of white matter in people who stutter. This disruption included all major white matter pathways leading in and out of the cerebellum. In our second, third, and fourth studies we examined functional activity at rest and during different types of speech. The brain networks used by people who stutter and controls largely overlapped. The brain regions that distinguished general traits and specific states of stuttering were somewhat task-specific. Subcortical activation in the basal ganglia and cerebellum was related to the frequency of dysfluent speech in the scanner. In our final study we examined performance on a variety of classical tasks of motor learning. We observed evidence of delayed learning in response to changes in environmental feedback in the stuttering group relative to controls. Within people who stutter, subgroups who differ according to heritability of the disorder may also differ in the balance of dopamine in the basal ganglia. Overall, we concluded that cerebellar alterations contribute to the general trait of stuttering, while basal ganglia disruption may reflect specific effects within stuttering. Our work supports a broader role of the subcortical system in speech production, generally.

O diagnóstico de uma doença grave e a hospitalização trazem consigo diversas situações adversas para a criança e o adolescente (e suas famílias). Os retornos constantes ao ambiente hospitalar para controlar os efeitos da progressão da doença podem influenciar no seu desenvolvimento integral. Dentre as doenças que necessitam de acompanhamento hospitalar durante período prolongado, o câncer infanto-juvenil vem sendo preocupação de estudos nas diferentes áreas do conhecimento, devido às diversas implicações associadas aos tratamentos necessários. O objetivo principal da presente dissertação foi investigar as associações e dissociações entre os diferentes fatores que podem contribuir para um perfil cognitivo mais preservado em crianças com leucemia na fase ativa do tratamento (aspectos psicossociais, acadêmicos, neuropsicológicos e clínicos propriamente ditos). Foram avaliadas habilidades neuropsicológicas (atenção, memória de trabalho, velocidade do processamento e funções executivas), estratégias metacognitivas, características comportamentais e competência social em crianças hospitalizadas com Leucemias. Igualmente foram investigados dados referentes ao nível socioeconômico, frequência/intensidade da participação à classe hospitalar, além de variáveis relacionadas ao tempo/tipo de tratamento médico elegido. Foi também examinado o panorama geral a respeito das práticas atuais em Classes Hospitalares, para servirem da base para as análises. Os resultados apontaram para uma tendência das habilidades de atenção, funções executivas (componentes controle inibitório, fluência verbal e flexibilidade cognitiva) e memória de trabalho (componente fonológico) se mostrarem mais preservadas ao longo do tratamento. Os componentes executivo central e memória de trabalho visuoespacial do modelo de memória de trabalho e velocidade do processamento parecem estar mais deficitários nestas crianças com leucemias. Quanto aos aspectos comportamentais e às competências sociais, pode ser observado que crianças com perfis mais preservados nesses quesitos tiveram melhores desempenhos em tarefas neuropsicológicas. A partir dos achados analisados ao longo da pesquisa, pode-se perceber que, apesar da heterogeneidade da amostra e dos resultados obtidos, a necessidade da avaliação neuropsicológica e do planejamento de estratégias que desenvolvam o potencial de aprendizagem em crianças com câncer durante e após o tratamento em Oncologia, sendo de suma importância a pesquisa de propostas educativas e de reabilitação que auxiliem essa população em suas especificidades. / The diagnosis of a severe disease and the hospitalization carry within’ many adverse situations for children and adolescents (and of their families). The constantly returns to the hospital setting to control the effects of disease’s progression may influence in their integral development. Within the diseases that need longer monitoring at the hospital setting, childhood cancer is a major concern in research of different areas of knowledge, due to many implications associated with treatments needed. The aim of the present thesis was to investigate associations and dissociations between the different factors that may contribute to a most preserved cognitive profile within children with leukemia in active phase of treatment (psychosocial, academic, neuropsychological and clinical aspects). It was evaluated neuropsychological skills (attention, working memory, processing speed and executive functions), metacognitive strategies measures and brief assessment of their behavior and social competences (CBCL) of hospitalized children with Leukemia. Socioeconomic aspects and frequency/intensity of Hospital-School attendance were also investigated, as well as the time/type of medical treatment chosen. It was also examined a general scenery of current practices in Hospital Schooling, to serve as a reference for the analyses. The results shows a tendency in attention and executive functions tasks, as well as working memory (phonological component), into a more preserved presentation, while the central executive and visuo-spatial working memory and processing speed were with deficits in children with leukemia. On behavioral and social competences, it could be observed that children with most preserved profiles in this question have better performance in neuropsychological tasks. Through the findings analyzed over the research, it’s possible to understand the importance in attention to protection/risk factors to cognitive development in childhood leukemia, especially in conjuncture of different factor with concomitant impairment. In this way, we reiterate the need of neuropsychological assessment in this context and strategy planning that develop the potential learning in children with cancer during and after Oncology treatment.