Assessment of executive functioning in neurodevelopmental disorders (e.g., autism) is a crucial aspect of neuropsychological evaluations. The executive functions are accomplished by the supervisory attentional system (SAS) and include such processes as inhibition, switching, and planning. Autism spectrum disorder (ASD) tends to present similarly to other neurodevelopmental disorders (e.g., ADHD). For example, ASD and ADHD may share similar etiological underpinnings in the frontostriatal system of the frontal lobe. Research on executive functioning in ASD has been mixed, thus the precise nature of executive functioning deficits in ASD remains equivocal. In recent years, simulation technologies have emerged as an avenue to assess neurocognitive functioning in individuals with neurodevelopmental disorders impacting frontostriatal function. Simulation technology enables neuropsychologists to assess neurocognitive functioning within a testing environment that replicates environments in which the subject is likely to be in everyday life, as well as present controlled, real-world distractions, which may be better able to tap “hot” executive functions. A Virtual Classroom Continuous Performance Test (CPT) has been used successfully to assess attention in individuals with neurodevelopmental disorders impacting frontostriatal function. The current study aimed to investigate executive functioning in individuals with high functioning ASD using a new construct driven Stroop assessment embedded into the Virtual Classroom. Group differences were found in the Virtual Classroom with distractions condition, indicating individuals with ASD may be more vulnerable to external interference control than neurotypical individuals.

Binge eating is a pervasive disordered eating behavior associated with numerous psychological and physical comorbidities. Preliminary research indicates that emotion regulation difficulties, behavioral impulsivity, and executive dysfunction may contribute to the onset and/or maintenance of these behaviors. However, few studies have utilized neuropsychological measures to examine this link, and the assessment of behavioral and cognitive emotion regulation strategies are limited in scope. The purpose of the current study was to gain a deeper understanding of the emotional, behavioral and cognitive processes associated with binge eating behavior. Greater clarity regarding how these factors relate to binge eating is critical to the development of effective treatment and prevention efforts. To address these aims, the current study examined the executive functioning, depression, behavioral impulsivity, distress tolerance, and emotion regulation strategies of 50 women engaging in weekly binge eating in the absence of compensatory behaviors; their outcomes were compared to 66 women with no history of binge eating. Hierarchical regression analyses revealed that groups did not significantly differ in executive functioning after controlling for depression, state anxiety, body mass, psychopharmaceutical use, and general intelligence; nonetheless, correlation analyses suggest that, among the binge eating group, individuals endorsing more frequent binge eating might have greater difficulties thinking flexibly or shifting attention. Secondary analyses indicated that individuals who binge eat are more depressed, are more likely to engage in impulsive behavior (but only when distressed), have more difficulties tolerating distress, are more likely to engage in rumination, self-blame, and catastrophizing, and less likely to focus on the positive. Although the current study is unable to determine whether these cognitive, emotional, and behavioral factors precede or follow binge eating episodes, outcomes have clinical implications. Specifically, programs focused on the prevention and treatment of binge eating should help individuals learn to better identify and tolerate difficult affective states and to utilize more adaptive means of coping. Outcomes also provide important directions for future research, including longitudinal designs to better understand the temporal associations of the current study’s variables, as well as suggestions to broaden and standardize neuropsychological assessment and scoring procedures to facilitate comparisons across studies.

The subthalamic nucleus (STN), which is the most common target for deep brain stimulation for Parkinson's disease, is known to be crucially involved in motor control. Recent appreciation of the potential non-motor side effects of STN deep brain stimulation, however, has led to speculation that the importance of this nucleus may also relate to processes involved in decision- making, particularly during high conflict scenarios. This thesis concerns itself with investigating the STN's role in action selection during conflict. I begin by recording local field potentials directly from the STN of Parkinson's disease patients while they perform a flanker task that has been shown to elicit theta (4-8 Hz) band activity in areas of the prefrontal cortex involved in cognitive control. I report that like the prefrontal cortex, the STN demonstrates elevated theta activity during conflict. I then test whether STN theta activity is related to that of the prefrontal cortex by recording from both sites simultaneously while patients perform a novel task that temporally separates conflict from stimulus onset or movement. This reveals that theta activity indeed becomes synchronized during conflict, with cortical oscillations driving those of the STN. Thirdly, I investigate how STN oscillations may affect firing rate dynamics by intra-operatively recording local field potentials and single unit activity from patients performing the flanker task. I report that both theta and beta (15-30 Hz) oscillations entrain STN neurons, but only during conflict. Finally, I record cortical and STN activity while a fourth group of patients performs the flanker task. This experiment confirms that cortico-STN theta synchrony is elevated during conflict and may also relate to across-trial adaptations to conflict and errors. Taken together these studies shed light on the mechanisms by which cortical structures may influence the STN during conflict and why STN deep brain stimulation may result in impulsivity.

Neuropsychological testing is one method used in the diagnosis of Alzheimer’s disease and other cognitive disorders. However, the testing process may be affected by subtle external factors which if not controlled for may have the ability to affect the scores obtained. The primary aim of this thesis was to investigate the effects of some of these external factors, namely caffeine, non-oily fish consumption and time of day. A secondary aim was to evaluate the use of a novel virtual assessment as a possible tool for the early detection of AD. Healthy elderly participants over the age of sixty with no existing cognitive impairment or neurological condition were recruited to take part. For each external factor investigated participants were required to undertake a cognitive assessment. The results demonstrated that subtle external factors present during a typical testing session have the ability to significantly affect the scores obtained. Scores on one part of the virtual test correlated with existing tests used for the early detection of cognitive impairment and were significantly lower in participants classified as mildly impaired. With further modification this test has the potential to be used as an early detection tool. The results have implications for the interpretation of neuropsychological test scores which may be considered when classifying participants, determining treatment interventions, selecting participants for research and making a diagnosis. These findings have important considerations for psychological and cognitive research that investigates human brain function.

Objective: Cultural neuropsychologists face barriers such as access to culturally appropriate psychometric instruments and norms. Further, three commonly encountered dilemmas in cultural neuropsychology include the following questions: (1) How do psychologists determine the best normative data to use for a given assessment scenario? (2) Do measures and models developed with North American samples also work in adaptations of instruments used with cross-cultural samples? (3) How can alternative and cost-effective measures be developed to meet the need for additional assessment tools? In response to these dilemmas, this dissertation consists of three papers aimed at developing Latinx and cultural neuropsychology psychometric resources for one of the most common cultural assessment scenarios: intelligence assessment amongst Spanish-speaking individuals using the Wechsler Adult Intelligence Scale – Fourth Edition (WAIS-IV). Chapter 1. A sample of 305 highly educated Colombian corporate executives completed the WAIS-IV. Data were scored using norms from Colombia, Chile, Mexico, Spain, United States, and Canada and scores were compared using ANOVA. Additionally, a comparative sociodemographic framework was established to contextualize our sample to the standardization samples and populations of the six countries. Chapter 2. Accumulating evidence indicates the original factor structures published in the Wechsler Intelligence Scales may not best describe the data captured by these tests, and instead supports a five factor Cattell-Horn-Carroll (CHC) model over a four factor Wechsler model, and a bifactor model over a higher-order model. Confirmatory factor analysis and structural equation modeling was used to evaluate factor structure of the Chilean-WAIS-IV (Wechsler, 2013) normative sample (ages 18-60; N=672) to better understand its psychometrics and to contribute to much needed cross-cultural study of alternative WAIS-IV factor models. Results marginally favored CHC and bifactor models but provided strong support for higher-order and Wechsler model variants as well, pointing to the need of further theoretical, methodological, clinical, and cross-cultural research. Chapter 3. The recent publication of the Chilean adaptation of the WAIS-IV has contributed to ongoing efforts to provide more psychometric instruments culturally appropriate for regions in South America. While not all assessment situations necessitate administration of the full WAIS and calculation of a full-scale intelligence quotient (FSIQ), there is virtually no published research on WAIS-IV short forms for estimating IQ in Latin America. This study used a rigorous series of methods (adapted from Smith et al., 2000) to develop robust estimated IQ short forms, aligned with Wechsler and CHC models, using the Chilean WAIS-IV standardization data (ages 18-90; N=887). Linear scaling was used to produce normative tables for the 28 best two-, three-, four-, and five subtest short forms of the Chilean WAIS-IV. Discussion. Together, the three papers of this dissertation provide psychometric guidance and resources not only for Latin American neuropsychologists in the area of intelligence assessment, but also more broadly for all cultural neuropsychology researchers and clinicians. / Graduate / 2020-06-25

In 2009 an estimated 33 million people were living with the Human Immunodeficiency Virus (HIV). Of this global population, 35% live in South Africa. Furthermore, sub-Saharan Africa is home to 80% of the world’s population of HIV-1 positive children and adolescents. The most prominent form of transmission of HIV in children in South Africa is from mother to child. Until 2004, South Africans had limited access to ARV treatment at and after birth due to the government legislation. As a consequence, treatment of HIV in children may only have been initiated after clinical presentation of immune deficiency. Therefore, currently, HIV-1 positive adolescents born during the period of restricted ARV-access may have experienced physical and developmental symptoms associated with the virus including neurological deficits, prior to initiating treatment. This study investigated the current psychomotor functioning, such as psychomotor speed, manual dexterity, graphomotor and visual-motor coordination of a group of low socio-economic HIV-1 positive adolescents in Johannesburg, South Africa, who are now on a managed antiretroviral programme and how this compared to a HIV negative contrast group. A Mann-Whitney U Test indicated a significant difference in mean non-dominant hand performance in the Grooved Pegboard Test between the two groups (U = 738, p < .05), with the HIV positive group performing slower than the HIV negative group. An independent samples t-test indicated a significant difference between groups in the Block Design subtest of the WISC-R [t(88) = -2.93, p < .01] where the HIV positive group performed significantly worse than the HIV negative group. Additionally, a Mann-Whitney U Test revealed a significant difference in number of errors made in the WISC-R Mazes subtest between groups (U = 736.50, p < .05), where the HIV negative group made more errors. Another Mann-Whitney U Test revealed a significant difference between groups in the ROCFT Copy score (U = 534.50, p < .01) where the HIV positive group achieved a significantly lower score than the HIV negative group. Lastly, a Mann-Whitney U Test demonstrated significant differences between the groups in the Trail Making Test A time (U = 445.00, p < .01), Trail Making Test B time (U = 509.00, p < .01), the number of errors made on the Trail Making Test B (U = 729.00, p < .05) and the difference between Trail Making Test B – A time (U = 769.50, p < .05) with the HIV positive group performing slower and making more errors in Part B than the contrast group. The findings of the current study imply that HIV-1 vertically-infected adolescents in Johannesburg, South Africa, on a delayed HAART programme appear to have persisting difficulties in complex psychomotor skills where an integration of functions is required. Furthermore, these results indicate an overall poor psychomotor performance in comparison to international normative data, supporting previous findings. Developmental, remedial and therapeutic recommendations were made.

South Africa has the most prominent percentage of individuals living with the Human Immunodeficiency Virus (HIV) in the world, with the most prominent form of transmission of HIV in South Africa being vertical mother-to-child transmission. From 1997 until 2004, South Africa had limited access to ARV treatment at and after birth due to the government legislation. As a consequence, treatment of HIV may only have been initiated after clinical presentation of immune deficiency. A paucity of information therefore exists regarding this population in addition to the specific age demographic of adolescents. Adolescents may be negatively influenced by the cortical thinning associated with HIV, and this study therefore aims to investigate the verbal fluency and vocabulary (in English) of 30 bi- or multilingual seropositive adolescents that are currently on a managed anti-retroviral programme in comparison to an HIV-negative contrast group of 70 bi- or multilingual adolescents in South Africa (matched for age, education, and socioeconomic status). The study found that there were no significant results between the HIV-positive and HIV-negative groups on the measures of vocabulary, semantic naming, or phonemic naming in ‘F’ as determined by their performance on the neuropsychological assessments. Significant results were noted between the HIV-positive and HIV-negative groups on the phonemic naming categories of ‘A’ and ‘S’ however, and negative correlations between performance in these categories and current viral load, and viral load at Highly Active Antiretroviral Therapy (HAART) initiation were also noted. This research formed part of a broader study examining the overall neurocognitive effects of HIV-1 infection in adolescents in South Africa.

Approximately 11.5 million Human Immunodeficiency Virus (HIV)-positive individuals were living in South Africa in 2007, many of whom were infected via mother-to-child transmission. The current study aimed to compare the attentional and concentration functioning of 30 seropositive adolescents on managed anti-retroviral (ARV) programmes, with a comparable group of 71 seronegative adolescents. The results showed that the uncorrected errors on trial 1; self-corrected errors on trial 2; time taken, uncorrected and self-corrected errors on trial 3 of the Stroop Colour-Word Interference Test; and the errors on the Trail Making Test Part B were significantly poorer in the seropositive sample. The results also indicated that the clinical variations in the HIV-positive sample, including the age at which ARVs were commenced; duration of ARV treatment; World Health Organisation (WHO) stage at diagnosis; starting and current CD4+ counts; and starting viral load, but with the exception of the current viral load, impacted significantly on test performance.

Mild traumatic brain injuries (MTBI) are the leading type of head injuries with appreciable risque of sequelae leading to functional and psychological deficits. Although mild traumatic brain injuries are frequently underdiagnosed by conventional imaging modalities, rapidly evolving techniques such as diffusion tensor imaging (DTI) reveal subtle changes in white matter integrity as a result of head trauma and play an important role in refining diagnosis, therapeutic interventions and management of MTBI. In this dissertation we use diffusion tensor imaging to detect the microstructural changes induced by axonal injuries and to monitor their evolution during the recovery process. DTI data were previously acquired from 11 subjects, football players of age 19-23 years (median age 20 years). Three players had suffered a mild traumatic brain injury during the season and underwent scanning within 24 hours after the injury with follow-ups after one and two weeks. A set of diffusion indices, such as fractional anisotropy, axial, radial and mean diffusivity were derived from the diffusion tensor. Changes in diffusion indices in concussed subjects were analyzed based on two different approaches: whole brain analysis, using tract-based spatial statistics (TBSS) and region of interest analysis (ROI). In both approaches we use a voxelwise analysis to examine group differences in diffusion indices between five controls and three concussed subjects for all DTI scans. Additional statistical analysis was performed between control groups consisting of five and three non-injured players. Both analyses demonstrated that the MTBI group reveals increase in fractional anisotropy and decreases in transversal and mean diffusivity in cortical and subcortical areas within 24 hours after the injury. / No changes were detected in TBSS analysis for the follow-up data sets. Furthermore, our ROI approach revealed multiples regions with significantly different voxels, non-uniformly distributed throughout the brain, for all diffusion indices in all three scans. Three of the diffusion indices fractional anisotropy, mean and transversal diffusivity showed higher vulnerability to head trauma in subcortical and cortical areas than in regions in the lower brain. Recovery of white matter pathways occured at different locations in the brain at one and two weeks after head trauma. Strong recovery was observed in mean and transversal diffusivity in subcortical areas that correspond to the corticospinal tract. No recovery was found for fractional anisotropy and axial diffusivity in the same region. Also, decreases in fractional anisotropy and increases in transversal and axial diffusivity were observed in the spleninum of the corpus callosum. As voxelwise analysis performed on DTI data revealed white matter regions, which exhibit changes in diffusion parameters in the concussed group for all three scans, we conclude that diffusion tensor imaging is a powerful technique for early detection of axonal injuries and may serve as an important tool for monitoring microstructural changes during the recovery process. / by Angelica Hotiu. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

A neuropsicologia infantil e uma area distinta dentro da neuropsicologia clinica e o seu surgimento e uma consequencia do reconhecimento de que as relacoes cerebrocomportamento na crianca diferem significativamente dessas relacoes no adulto. Diversos testes neuropsicologicos tem sido desenvolvidos especialmente para administracao em computador, incluindo a bateria CANTAB que tem sido amplamente utilizada em pesquisas com diferentes grupos de idade e patologias. Em relacao ao desenvolvimento, alguns aspectos da atencao estao presentes no inicio da infancia enquanto outros continuam a se desenvolver ao longo da infancia e adolescencia. A memoria sofre inumeras alteracoes ao longo da vida, especialmente na idade pre-escolar. E as funcoes executivas demoram mais tempo para se desenvolver por completo e estudos apontam que alguns componentes ja estao presentes de forma imatura em criancas entre os 6 e 12 anos de idade, mas a completa maturacao acontece com a idade. O objetivo dessa pesquisa foi investigar o desenvolvimento da atencao, memoria e funcoes executivas em criancas e adolescentes dos 6 aos 12 anos de idade com o CANTAB, buscando padroes especificos de desenvolvimento para os componente dessas funcoes. Foram avaliados 85 criancas e adolescentes (43 masculino) entre 6 e 12 anos de idade, sem historico de disturbios neurologicos e/ou psiquiatricos, exposicao cronica a agentes toxicos, lesao ou cirurgia cerebral e problemas de desenvolvimento. Foram utilizados o teste Matrizes Progressiva Coloridas de Raven e os seguintes subtestes do CANTAB: Choice Reaction Time, Rapid Visual Information Processing, Pattern Recognition Memory, Delayed Matching to Sample, Spatial Recognition Memory, Spatial Span, Stockings of Cambridge, Intra-Extra Dimensional Set Shift, Stop Signal Task e Information Sampling Task. Os resultados indicaram que a atencao, a memoria e as funcoes executivas apresentam melhora no desenvolvimento nas idades avaliadas. A atencao visual simples, percepcao visual e capacidade de conceituacao ja estao desenvolvidas aos 6 anos. A amplitude atencional, memoria visual, memoria espacial, flexibilidade mental e controle mental estao em desenvolvimento nas idades avaliadas e apresentam um bom desempenho aos 12 anos. O planejamento e atencao sustentada apresentaram melhoras, mas ainda nao alcancaram o pleno desenvolvimento. A, tomada de decisao e controle inibitorio nao apresentaram aprimoramentos significativos e sua maturacao deve ocorrer apos os 12 anos. A bateria CANTAB se mostrou eficaz na avaliacao de criancas e adolescentes brasileiros de 6 a 12 anos de idade com alta aplicabilidade nessa amostra e resultados compativeis com a literatura. A comparacao entre os nossos resultados e aqueles encontrados nos estudos internacionais com o CANTAB indica compatibilidade entre boa parte dos grupos etarios avaliados, independentemente das diferencas culturais existentes / Child neuropsychology is a distinct area in the clinical neuropsychology and its emergence is a consequence of the acknowledgment that the brain-behavior relationships in child differ significantly from those in adult. Several neuropsychology tests have been developed to be administered in computers, including the CANTAB that has been widely used by researchers concerning different ages and pathologies groups. In regard to the development, some aspects of attention are present in the beginning of childhood while others continue to develop along the childhood and youth. Memory processes undergo many changes throughout life, especially in preschool age. Executive functions take longer to fully develop and researches indicate that some components are present in immature form on child between 6 to 12 years old, but the complete ripening occurs with age increase. The aim of this work was to investigate the development of attention, memory and executive functions in children and teenagers from 6 to 12 years old using the CANTAB, and verify if there are specific patterns of development for the components of these functions. There were evaluated 85 children and teenagers (43 male) between 6 to 12 years old with no history of neurological and/or psychiatric disorders, chronic exposures to toxic agents, injury or brain surgery and development disorders. They were submitted to the Ravens progressive matrices and the following CANTABs subtests: Choice Reaction Time, Rapid Visual Information Processing, Pattern Recognition Memory, Delayed Matching to Sample, Spatial Recognition Memory, Spatial Span, Stockings of Cambridge, Intra-Extra Dimensional Set Shift, Stop Signal Task e Information Sampling Task. The results indicated improvements in attention, memory and executive functions in the development in the age groups evaluated. Simple visual attention, visual perception and conceptualization capacity seem to be developed at 6 years old. Attentional span, visual memory, spatial memory, mental flexibility and mental control are in ongoing development in the age groups evaluated, and a good performance is reached at 12 years old. Planning ability and sustained attention showed improvements in age groups evaluated but they have not reached fully development. Decision making and inhibitory control do not showed significant improvement and their ripening should occur after the 12 years old. The CANTAB battery was effective to evaluate Brazilians children and teenagers from 6 to 12 years old with high applicability in this sample and results consistent with the literature. The comparison between our results and those found in the international studies with CANTAB indicates compatibility in almost all age evaluated, regardless cultural differences