xiii, 143 p. : ill. (some col.) / The cognitive ability to group information into chunks is a well known phenomenon, however, the effects of chunking on visual representations is not well understood. Here we investigate the effects of visual chunking using Gestalt grouping principles in two tasks: visual working memory change detection and multiple object tracking. Though both these tasks have been used to study cognitive functions in the past, including object-based attention, attentional control and working memory capacity, the effect of grouping on mental representations in these tasks has not been well characterized. That is, while researches have measured effects of grouping on behavioral output in similar tasks, there are few studies of the effects of grouping on neurophysiological indices of object representations. Indeed, these current studies are the first to use event-related potentials (ERPs) to elucidate the effect of grouping on active mental representations of visual stimuli. In the visual working memory task, observers remembered either the color or orientation of pacman stimuli across a delay. We manipulated the collinearity of these objects, whether or not they formed a Kanizsa triangle figure, and measured the behavioral and electrophysiological effects. In the multiple object tracking task, a subset of identical stimuli were briefly cued as targets and then their motion was tracked by participants. We manipulated whether and which Gestalt heuristics were used to bind targets together during their motion and measured the effects on behavior and electrophysiology. In both tasks we compared the grouped to ungrouped conditions. We found that across experiments and tasks behavioral performance was enhanced in grouping conditions compared to ungrouped conditions. Furthermore, the waveforms evoked by grouped stimuli were reduced compared to waveforms produced in response to locally identical but ungrouped stimuli. These data suggest that the mental representation of visual objects may be reshaped moment-by-moment by grouping cues or task demand, giving rise to a flexible, active and dynamic yet parsimonious representation of the visual world. / Committee in charge: Edward K. Vogel, Chair; Edward Awh, Member; Ulrich Mayr, Member; Paul van Donkelaar, Outside Member

abstract: Individual differences in working memory capacity partly arise from variability in attention control, a process influenced by negative emotional content. Thus, individual differences in working memory capacity should be predictive of differences in the ability to regulate attention in emotional contexts. To address this hypothesis, a complex-span working memory task (symmetry span) was modified so that negative arousing images or neutral images subtended the background during the encoding phase. Across three experiments, negative arousing images impaired working memory encoding relative to neutral images, resulting in impoverished symmetry span scores. Additionally, in Experiment 3, both negative and arousing images captured attention and led to increased hit rates in a subsequent recognition task. Contrary to the primary hypothesis, individual differences in working memory capacity derived from three complex span tasks failed to moderate the effect of negative arousing images on working memory encoding across two large scale studies. Implications for theories of working memory and attention control in emotional contexts will be discussed. / Dissertation/Thesis / Masters Thesis Psychology 2015

abstract: By examining the cognitive mechanisms behind human memory, the author hypothesizes that instrumental conductors can more quickly and effectively internalize music scores. With this theory, conductors could offer more informed and nuanced communications to their ensembles. Furthermore, these ideas could be incorporated into how conducting is taught to younger students by cultivating a more in-depth understanding of the music being studied. This research paper surveys current trends in cognitive science related to the interactions of long-term memory (LTM) and short-term memory (STM) concerning score study and memorization employed by instrumental conductors. The research is divided into three sections, beginning with an examination of the key literature from the field of cognitive science. It continues with an overview of current musicological research and applications and finally concludes with a review of current instrumental conducting pedagogy that include discussions of memory. Moreover, recommended steps and a potential framework to incorporate cognitive science research into future conducting pedagogies are further outlined. The primary cognitive theory of focus is the Working Memory Theory of Alan Baddeley and Graham Hitch. / Dissertation/Thesis / Doctoral Dissertation Music 2017

abstract: Working memory capacity and fluid intelligence are important predictors of performance in educational settings. Thus, understanding the processes underlying the relation between working memory capacity and fluid intelligence is important. Three large scale individual differences experiments were conducted to determine the mechanisms underlying the relation between working memory capacity and fluid intelligence. Experiments 1 and 2 were designed to assess whether individual differences in strategic behavior contribute to the variance shared between working memory capacity and fluid intelligence. In Experiment 3, competing theories for describing the underlying processes (cognitive vs. strategy) were evaluated in a comprehensive examination of potential underlying mechanisms. These data help inform existing theories about the mechanisms underlying the relation between WMC and gF. However, these data also indicate that the current theoretical model of the shared variance between WMC and gF would need to be revised to account for the data in Experiment 3. Possible sources of misfit are considered in the discussion along with a consideration of the theoretical implications of observing those relations in the Experiment 3 data. / Dissertation/Thesis / Doctoral Dissertation Psychology 2018

Introdução: Alterações no neurodesenvolvimento podem estar associadas à subnutrição. As consequências da subnutrição dependerão da idade da criança, do tipo, duração e grau da subnutrição. As possíveis alterações ocasionadas pela subnutrição são variáveis, porém, dentre essas alterações, a linguagem que é considerada uma das atividades cognitivas humanas mais elaboradas, apresenta grandes riscos. Objetivo: Caracterizar e analisar a linguagem oral e processamento fonológico de crianças que foram diagnosticadas com subnutrição em idade precoce adotando como referencial o desempenho de crianças na mesma faixa etária com bom e mau desempenho de linguagem receptiva e expressiva nas diferentes tarefas de memória de trabalho, consciência fonológica, fonologia e vocabulário. Método: Crianças com histórico de subnutrição em idade precoce (antes dos três anos de idade) e recuperadas nutricionalmente, foram avaliadas quanto à linguagem receptiva e expressiva, seu componente fonológico, vocabulário, consciência fonológica, memória de trabalho fonológica e memória visuo-espacial. Para possibilitar a análise desses componentes nessas crianças e se estabelecer parâmetro de comparação, foi realizada a avaliação de crianças eutróficas (sem histórico de subnutrição) na mesma faixa etária, pelos mesmos testes, e divididas em dois grupos (G1 crianças que apresentavam bom desempenho de linguagem e G2 - crianças que apresentavam mau desempenho de linguagem). O desempenho dos grupos foi comparado utilizando-se para inferência estatística dos resultados os testes t-student e Kruskal-Wallis. Para verificar possíveis associações entre os componentes avaliados foi utilizado o teste Exato de Fisher. Resultados: Nas crianças com histórico de subnutrição, observou-se que a criança que apresentou o quadro de subnutrição com menor idade, maior tempo de duração do diagnóstico e pior grau apresentou mau desempenho de linguagem e pior desempenho em todas as provas avaliadas no estudo quando comparada aos dois grupos de crianças eutróficas. Esse resultado sugere que essas variáveis (idade, duração e tipo) da subnutrição podem ser determinantes para os efeitos sobre a linguagem e processamento fonológico. As demais crianças que apresentaram variações na idade, duração e tipo de subnutrição assemelharam-se em algumas provas ao grupo G1 e em outras com o G2. Esse resultado reforça a suposição de que essas variáveis levam a diferentes prejuízos em linguagem e/ou processamento fonológico. Em relação à comparação de desempenho entre G1 e G2, os grupos apresentaram diferença significativa nas provas de memória de trabalho, tanto a fonológica quanto a visuo-espacial, não houve diferença para consciência fonológica. Os resultados não apontaram a existência de associação entre desempenho de linguagem, alteração fonológica e de vocabulário. Conclusões: Este estudo sugere que crianças que tiveram subnutrição no período crítico do desenvolvimento cerebral, mesmo após recuperação nutricional, apresentaram alterações cognitivas duradouras e importantes. / Introduction: Changes in the neurodevelopmental process may be related to undernutrition condition. The consequences of undernutrition appear to be dependent of childrens age, type, duration and degree of undernutrition. Undernutrition related alterations are diversified and the language that is considered to be one of the most relevant human cognitive skills may represent important risks. Objective: The aim of this study was to characterize and analyze the oral language and phonological processing of children diagnosed with undernutrition at early age using as standard of comparison the childrens performance in the same range age. Methods: Children presenting undernutrition at early age (diagnosed before reaching 3 years of age) with nutritional recovery were enrolled in this study and assessed for receptive and emissive language, phonology, vocabulary, phonological awareness, visuospatial and phonological working memories. Data obtained from these children were correlated with results collected from eutrophic children in the same range of age without undernutrition condition which were randomly divided in 2 groups (G1- children without language deficit and G2 children with language deficit) and submitted to the same tests. Data obtained from each group were averaged and compared using t-student and Kruskal-Wallis. Possible association between different language components was assessed by Fishers Exact tests. Results: In the children diagnosed with udernutrition, the infant with the highest level of disease (detected with the lower age and with the high long duration) shows significant language deficit and lower performance in all of the applied tests when compared with G1 and G2. This result suggests that age and duration and type of undernutrition may be determinant on the effects of language and phonological awareness. No significant differences were found between groups concerning phonological awareness. No association was found between language deficit and changes in phonology or vocabulary. Conclusions: Data obtained from this study suggest that children diagnosed with undernutrion during the critical period of brain development may present relevant and long-lasting cognitive alterations, even after nutritional recovering. In addition, data suggest that low performance may compromise working memories phonological and visuospatial.

No description available.

Schizophrenia is a complex and severe psychiatric disorder with positive symptoms, negative symptoms and cognitive deficits. Preclinical neurobiological studies showed that alterations of dopaminergic and glutamatergic neurotransmitter circuits involving the prefrontal cortex resulted in cognitive impairment such as working memory. Functional activation and functional connectivity findings of functional Magnetic Resonance Imaging (fMRI) data provided support for prefrontal dysfunction during fMRI working memory tasks in individuals with schizophrenia. However, these findings do not offer a neurobiological interpretation of the fMRI data. Biophysical modelling of functional large-scale networks has been designed for the analysis of fMRI data, which can be interpreted in a mechanistic way. This approach may enable the interpretation of fMRI data in terms of altered synaptic plasticity processes found in schizophrenia. One such process is gating mechanism, which has been shown to be altered for the thalamo-cortical and meso-cortical connection in schizophrenia. The primary aim of the thesis was to investigate altered synaptic plasticity and gating mechanisms with Dynamic Causal Modelling (DCM) within functional large-scale networks during two fMRI tasks in individuals with schizophrenia. Applying nonlinear DCM to the verbal fluency fMRI task of the Edinburgh High Risk Study, we showed that the connection strengths with nonlinear modulation for the thalamo-cortical connection was reduced in subjects at high familial risk of schizophrenia when compared to healthy controls. These results suggest that nonlinear DCM enables the investigation of altered synaptic plasticity and gating mechanism from fMRI data. For the Scottish Family Mental Health Study, we reported two different optimal linear models for individuals with established schizophrenia (EST) and healthy controls during working memory function. We suggested that this result may indicate that EST and healthy controls used different functional large-scale networks. The results of nonlinear DCM analyses may suggest that gating mechanism was intact in EST and healthy controls. In conclusion, the results presented in this thesis give evidence for the role of synaptic plasticity processes as assessed in functional large-scale networks during cognitive tasks in individuals with schizophrenia.

Background: Children with chromosome 22q11.2 deletion syndrome (22q11.2DS) exhibit nonverbal learning disability that may manifest in part because of working memory (WM) deficits. 22q11.2DS is a complex developmental disorder with serious physical, learning, cognitive, and psychiatric symptoms including a risk of developing schizophrenia 30 times that of the general population. WM impairment likely contributes to and exacerbates learning difficulties, school problems, existing neuropsychological disorders such as attention deficit hyperactivity disorder (ADHD); and a poor WM may be a biological risk marker for future mental illness. WM impairment is established in this population, but less is known about its neurological origins. Frontoparietal cortical development and function are key to WM processing. In the neurotypical developing brain, studies indicate activation associated with WM shifts from parietal to frontal regions with age. However, in children with 22q11.2DS, activation is restricted to the frontal cortex, and volumes are reduced in parietal regions where abnormal tractography abides. The overarching aim of this study was to determine the neural origins of WM impairment in people with 22q11.2DS. Methods: We measured WM in children and adolescents with (n = 29) and without (n = 27) 22q11.2DS using the WISC-IV and a computer-based spatial working memory task (SWMT) task. Participants’ brains were scanned using high-resolution magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI). Focusing on brain morphometry and structural connectivity within frontoparietal networks, we investigated neural underpinnings of WM processing in 22 children with 22q11.2DS and 19 typically developing (TD) controls ages 7 to 16 (M = 12.13 ± 2.41). A connectome mapping network involved in WM processing was constructed by superimposing cortical segmentations on white-matter tractography. Results: Children with 22q11.2DS had impaired working memory performance. Individuals’ performance on our SWMT moderated the association between diagnosis and gray and white matter macro and microstructure. Children with 22q11.2DS with better working memory had larger lateral orbitofrontal volumes, greater axial diffusivity in the left superior frontal to superior parietal tract, and smaller volume in the right superior frontal to lateral orbitofrontal tract. Poorer performance in children with 22q11.2DS was associated with smaller right superior parietal and superior frontal cortical volumes. Conclusions: Children with 22q11.2DS performed worse on measures of working memory. Their performance was related to regional cortical volume differences and white matter microstructure abnormalities in the frontal and parietal lobes. These are brain regions consistently implicated in WM processing.

The purpose of the current study was to examine neuropsychological functioning in patients with bipolar disorder (BD) with psychotic features. Data from a large, epidemiological study of patients with first-episode psychosis was used to examine verbal learning and working memory 10 years after onset of psychosis in patients with BD relative to patients with schizophrenia (SZ) and patients with psychotic major depressive disorder (MDD). Cross-sectional comparisons of verbal learning and working memory at the 10-year follow-up mirrored findings of relative performance at the 2-year follow-up (Mojtabai, 2000), as patients with SZ performed significantly worse than patients with psychotic affective disorders. When FEP patients' cognitive performance was examined longitudinally, all groups showed non-significant decline over time, with no significant diagnostic group differences after accounting for current symptoms. More frequent hospitalizations and longer treatment with antipsychotics were associated with poorer performance on cognitive testing 10 years after illness onset, but these associations disappeared when controlling baseline cognitive performance. Within the BD sample, current positive and negative psychotic symptoms were associated with poorer performance on cognitive testing. After controlling for baseline cognitive performance, markers of clinical course were unrelated to cognitive performance, consistent with existing literature on longitudinal cognitive functioning in patients with BD. The current findings support a neurodevelopmental model of verbal learning and working memory deficits in patients with bipolar disorder.

No description available.