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"The purpose of this study was to develop an assessment tool to measure musical training and experiences for grouping participants in human neuroimaging research studies. To fulfill the purpose of this study, the researcher: 1. Completed a comprehensive review of the research literature to establish the essential content of the assessment tool; 2. Developed an assessment tool to survey subjects about their musical training and experiences; 3. Pilot tested the assessment tool, and revised the tool according to the preliminary analyses of the validity, reliability, and usefulness of the assessment tool; 4. Established the content validity and reliability of the assessment tool with subjects participating in a neuroimaging study designed to analyze the influences of musical training and experiences on brain structures and functions, and 5. Determined if the assessment tool functioned effectively in the selection and grouping of musically trained and musically untrained subjects for neuroimaging studies. The assessment tool was administered to a purposive sample (N = 42) in the southeastern region of the United States. Participants were recruited on the basis of musical training, both the existence and lack thereof. The assessment was completed via the web-based platform, Qualtrics. Coding of survey responses indicated differences in the participant pool that resulted in two groups: Musicians and Non-musicians. Further investigation yielded two subgroups within the Musician participant group: Moderate and Advanced. Validity of the assessment tool was established using a three-step construction process, (a) development of a draft based on the existing literature and the musical training knowledge of the researcher, (b) a review of the assessment tool by five music educators and performers, and (c) administration to a pilot group of five additional people with varying levels of musicianship. Additional content validity was completed by external reviewers by rating each assessment item using a Likert-type scale: 1 - Not important, 2 - Slightly important, 3 - Fairly important, 4 - Important, and 5 - Very important. Reliability was established using interrater reliability and was determined to be 88.9%. A discussion was presented that included the differences among participants that made their musical training and experiences unique compared with other participants. Implications were discussed regarding the usage possibilities for the survey, as well as the potential effects of the survey on human neuroimaging research."--Abstract from author supplied metadata

Schizophrenia is the most extreme manifestation of schizotypy, a continuum of symptoms and impairment that ranges from minimal impairment to full-blown psychosis. "Schizophrenia has been described as a disorder of disrupted context integration (CI), the ability to assimilate internal and external information into coherent mental representations. CI in schizotypy is often measured with the AX-Continuous Performance Task (AX-CPT) and the Dot Pattern Expectancy (DPX) task. Research using these tasks indicated CI deficits along the schizotypy spectrum, but has primarily been conducted with schizophrenia patients. There have been mixed findings regarding outcomes such as error patterns and the association of CI deficits with schizotypy symptom dimensions. Further, conclusions were limited by generally small sample sizes, heterogeneous patient variables, and varied task parameters across studies. The current study used systematic review and meta-analysis to collect and synthesize data on AX-CPT and DPX performance across the schizotypy spectrum. CI impairment was present across the schizotypy spectrum. CI deficits in schizophrenia were substantial in magnitude and correlated with disorganized and negative symptom dimensions. Error patterns suggested a specific deficit in CI, which was larger than deficits attributed to broader cognitive impairment and general psychopathology. When examining subgroups, CI performance was comparable between chronic and first-episode schizophrenia patients. Groups at risk to develop schizophrenia demonstrated moderate CI impairment. The results were generally robust across task parameters and there was no evidence of reporting biases. In sum, these findings lend additional support to theories suggesting that CI is a stable vulnerability factor for schizophrenia."--Abstract from author supplied metadata

Response inhibition is the suppression of actions that are inappropriate given some wider context or goal, a capacity that is vital for everyday functioning. In this thesis the theoretical backdrop of executive functioning is discussed, before exploring current research into response inhibition and its neural underpinnings. A theory by Mostofsky and Simmonds (2008) holds that when the decision to inhibit a behavior is a complex one, task dependent parts of an inhibitory network in the prefrontal cortex are utilized. The current thesis argues on the basis of observed biases in the literature, for the possibility that this task dependent engagement features domain specific lateralization. In order to investigate this, a transcranial magnetic stimulation [TMS] experiment is then presented where four go/no-go tasks, spread across language and spatial domains in complex and simple forms, are performed following TMS. Stimulation sites include the right posterior inferior frontal gyrus, the left posterior inferior frontal gyrus, and sham stimulation. Results are then discussed, however implications are limited, likely due to low statistical power.

Cognitive neuroscience of aging research investigates neural mechanisms associated with cognitive stability and decline in older versus younger adults. This field has been dominated by neuroimaging techniques that emphasize brain function over structure, gray over white matter, and isolated brain regions over neural networks. Furthermore, the scope of the field has been limited by a focus on explicit cognitive processes (e.g., working memory, executive functions). To broaden our current understanding, this dissertation examined relationships among healthy aging, implicit sequence learning, and white matter integrity. In the first study, diffusion tensor imaging (DTI), which measures diffusion of molecular water, was used to characterize age-related differences in multiple measures of white matter integrity. Results revealed age-related declines in fractional anisotropy (FA), a measure of diffusion coherence, with the magnitude of these differences being largest in frontal white matter. Additional measures of diffusion parallel (axial diffusivity, AD) and perpendicular (radial diffusivity, RD) to the primary diffusion direction revealed region-specific patterns of age group differences that may reflect differential aging of microstructural (e.g., degree of myelination) and macrostructural (e.g., coherence of fiber orientation) properties of white matter. In the second study, white matter integrity correlates of implicit sequence learning were examined in younger and healthy older adults. Implicit sequence learning was assessed with the alternating serial reaction time task (ASRT). Significant learning was seen in both age groups (i.e., faster and more accurate responses to frequent, pattern-related events compared to intervening, random events), with an age-related decline in the late learning stage. In line with functional imaging studies that identified subcortical (e.g., caudate, hippocampus) and cortical (e.g., dorsolateral prefrontal cortex, DLPFC) correlates of implicit sequence learning, integrity of caudate-DLPFC and hippocampus-DLPFC tracts was related to sequence learning in the ASRT, and these relationships did not differ with age group. Additionally, age-related differences in caudate-DLPFC tract integrity mediated age-related differences in sequence learning. Taken together, results of these studies support the theory of white matter disconnection, which proposes that age-related declines in white matter integrity may explain age-related cognitive declines, as communication between distributed cortical regions involved in the task is disrupted.