Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

Thesis (Ph. D.)--York University, 2000. Graduate Programme in Psychology. / Typescript. Includes bibliographical references (leaves 209-273). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ59157.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 232-242).

This study examined processing speed and executive function late effects in survivors of pediatric ALL (hereafter referred to as Survivors). Late effects are long-term, treatment-related health problems associated with the neurotoxic side-effect of cancer treatment on brain development. Processing speed —mental and motor speed with which a person can solve nonverbal problems — was estimated via an composite of processing speed attained from several measures of processing speed. Executive function — a collection of processes orchestrated in the performance of purposeful, goal-directed behavior — was measured using the Parent and Teacher forms of the Behavior Rating Inventory of Executive Function (BRIEF). This study also explored the effect of previously identified risk factors for processing speed and executive function late effects. Finally, executive function late effects were further explored via the use of performance-based measures, including the Tower and Trail Making (Condition 4) tests of the Delis-Kaplan Executive Function System (D-KEFS). Hypotheses included (1) Survivors would demonstrate significantly poorer processing speed; (2) late effects risk factor variables (i.e., greater elapsed time since completion of treatment, lower age at diagnosis, and higher intensity of treatment) would predict poorer processing speed; (3) female gender would predict poorer processing speed; (4) parents and teachers would demonstrate both low interrater agreement (Hypothesis 4a) and differ significantly in the severity (Hypothesis 4b) of their ratings of Survivor executive function; (5) parent and teacher ratings of executive function would indicate significantly poorer Survivor metacognition (Hypothesis 5a), whereas Survivor behavioral regulation would not differ significantly (Hypothesis 5b); (6) risk factor variables would predict poorer Parent and Teacher ratings of Survivor metacognition; (7) female gender would predict poorer Parent and Teacher ratings of Survivor metacognition; (8) survivor processing speed and Parent and Teacher ratings of executive function would exhibit a positive relationship; and (9) poorer Survivor processing speed would predict poorer parent and teacher ratings of executive function. Results provided support for hypothesis 1 and 5a. Partial support was obtained for hypotheses 4a, 4b, and 7. Hypotheses 2, 3, 5b, 6, 8, and 9 were not supported. / text

published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

The purpose of this study was to determine the relationship between anxious/depressed and withdrawn symptoms and performance on a variety of cognitive and academic achievement measures. The sample included 343 subjects, drawn from a pool of subjects aged 6 to 11 years who were part of a sleep apnea study. A comprehensive battery of selected tests that measured cognitive and academic achievement function was administered to all sampled subjects. Parents of the subjects were given an instrument to complete in order to assess behavior function.The obtained data were analyzed by using Pearson Product Moment Correlation Coefficient analyses, T test procedures, and chi-square analyses. A significant negative correlation was found between anxious/depressed and withdrawn symptoms and the following cognitive and academic measures: general intelligence including verbal and nonverbal abilities, language, specific executive function skills, attention and processing speed, psychomotor speed and coordination with the dominant hand trial, and a subtest assessing math problem solving skills.There were statistically significant differences found between those subjects who obtained approaching borderline and clinically significant anxious/depressed, withdrawn, and both anxious/depressed and withdrawn symptoms on the following cognitive and academic measures: general intelligence including verbal and nonverbal abilities, language, specific executive function skills, attention and processing speed, psychomotor speed and coordination with the dominant hand, the interference and/or delayed recall trial of a memory task, and basic reading, math problem solving, and early spelling/writing skills.There was a significant difference found with regard to parent education level for children identified with withdrawn symptoms as compared to children without these symptoms but there were no other differences with regard to age, gender, ethnicity, or parent education level for children identified with anxious/depressed or withdrawn symptoms as compared to children without these symptoms. Additionally, Caucasian children performed significantly better than Hispanic children on a variety of the cognitive and academic measures.Overall, these findings support the hypotheses that depressive symptomatology does impact performance on cognitive and academic measures. Additionally, methodological problems for exercising caution in the interpretation of obtained findings were discussed. The implications of these findings for psychological practitioners, educators, and physicians were described.

Current models of face perception suggest independent processing of identity and expression, though this distinction is still unclear. Using converging methods of psychophysics and functional magnetic resonance imaging (fMRI) in healthy and patient populations we assessed the relationship between these two perceptual processes. First, using perceptual aftereffects, we explored the neural representations underlying identity and expression. The expression aftereffect only partially transferred across different identities, suggesting adaptation within identity-invariant and identity-dependent expression representations. Contrarily, the identity aftereffect fully transferred across different expressions. This asymmetry cannot be explained through low-level adaptation. The identity-dependent component of the expression aftereffect relies on adaptation to a coherent expression, not low-level features, in the adapting face. Thus adaptation generating the expression aftereffect must occur within high-level representations of facial expression. Second, using fMRI adaptation, we examined identity and expression sensitivity in healthy controls. The fusiform face area and posterior superior temporal sulcus showed sensitivity for both identity and expression changes. Independent sensitivity for identity and expression changes was observed in the precuneus and middle superior temporal sulcus respectively. Finally, we explored identity and expression perception in a neuropsychological population. Selective identity impairments were associated with inferior occipitotemporal damage, not necessarily affecting the occipital or fusiform face areas. Impaired expression perception was associated with superior temporal sulcus damage, and also with deficits in the integration of identity and expression. In summary, psychophysics, neuroimaging and neuropsychological methods all provide converging evidence for the independent processing of identity and expression within the face network. However, these same methods also supply converging evidence for a partial dependence of these two perceptual processes: in the expression aftereffect, the functional sensitivities of the FFA and pSTS, and identity deficits observed in a patient with primarily impaired expression perception and a spared inferotemporal cortex. Thus, future models of face perception must incorporate representations or regions which independently process identity or expression as well as those which are involved in the perception of both identity and expression.

A significant goal in studies on learning and memory is to relate cellular plasticity to the modification of behaviour. The phenomenon of dual-process learning affords an ideal opportunity to explore the complexities inherent in establishing this relationship. Dual-process learning occurs when depression (habituation) and facilitation (sensitization) are expressed simultaneously within a neural network and compete to determine the behavioural outcome. A large body of literature is reviewed to define characteristics which are common across the neural networks that exhibit dual-process learning: depression occurs at loci early in the reflex pathway, upstream of the modulatory system necessary for the induction of facilitation. Consequently, depression not only competes directly with facilitation for the determination, of behavioural change (by serial and/or parallel expression), but depression also precludes the ongoing development and maintenance of sensitization (by serial induction). A mathematical model is presented to formally describe the nature of this competition and how this competition leads to the kinetics of dual-process learning. The tentacle withdrawal reflex of the snag Helix aspersa exhibits dual-process learning and was further investigated in this study. The neural circuit mediating tentacle withdrawal is described along with the nature and the location of plasticity which occurs within that circuit. In turn, plasticity at the cellular level is related, via the network level, to plasticity at the behavioural level. The data demonstrate the importance of localizing the sites of plasticity within a neural network in order to explain (1) how plasticity at a particular locus influences plasticity occurring elsewhere in the network and (2) how plasticity at different loci affect different aspects of behaviour.

A preterm birth is associated with increased risk for neurocognitive deficits, but there is a need to further investigate brain/behavior relations among younger school age children born preterm. The main purpose of this study was to investigate relations between brain volumes and neuropsychological functioning, with an additional aim of examining side preference, among 18 school age children, nine born extremely/very preterm and nine born at-term. Brain volumes were examined using 3T MRI, neuropsychological functioning by WISC-IV and side preference through laterality observations. The children born preterm had, in general lower total brain volume, gray matter and WISC-IV score. Contrary to previous findings no difference was found regarding white matter volumes. Stronger right hand preference was associated to higher perceptual reasoning ability among both preterm and at-term born children, but the associations between right hand preference and brain volumes differed between the groups. The results in this study support previous findings showing long-term neurocognitive effects of a preterm birth.

The purpose of this study was: (a) to replicate those parts of the Pontius and Ruttiger (1976) study in which they found a lower frequency of the ability to express maturity in narrative stories (appropriate change of behavior during an intervening circumstance) within a group(b) to verify with an accepted measure of frontal lobe dysfunction (Wisconsin Card Sorting Test) the conclusion of Pontius and Ruttiger that subjects can be classified into two groups, one demonstrating frontal lobe dysfunction and Level IV of juvenile delinquents versus a group ofnormal controls; the other demonstrating normal frontal lobe development, on the basis of the Narratives Test; and (c) to determine the efficacy of a newly developed Perseveration Response as a measure of frontal lobe dysfunction.The effectiveness of the Narratives Test as a measure of fronal lobe dysfunction could not be verified as determined by its relationship with the Wisconsin Card Sorting Test.It was, however, concluded, on the basis of a successful replication, that the Narratives Test canconsistently measure Level IV maturity but that there is no basis to specifically associate an inability to change behavior appropriately in reponse to an intervening circumstance in narrative stories with frontal lobe dysfunction.Even though that part of the Pontius and Ruttiger (1976) study dealing specifically with juvenile delinquents was successfully replicated, results of the present study relating to normals differed significantly from the Pontius and Ruttiger findings.The present study identified a significantly lower frequency of Level IV maturity failures among normals than was true in the Pontius and Ruttiger study.Based on the correlation between the Wisconsin Card Sorting Test and the Perseveration Category Error Score, the present study did not support the validity of this scoring procedure as a viable measure of frontal lobe dysfunction. A verification of the Perseveration Category Error Score with a sample of documented frontal lobe patients and matched control groups is suggested.