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Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Psychology." Includes bibliographical references (p. 73-86).

Thesis (B.A.)--Haverford College, Dept. of Psychology, 2008. / Includes bibliographical references.

Thesis (B.A.)--Haverford College, Dept. of Psychology, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Psychology." Includes bibliographical references (p. 85-91).

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 75-79). Also available via the World Wide Web.

Brain maturation is an important factor in cognitive, emotional, behavioural and motor development during childhood and adolescence. This study uses multi-modal magnetic resonance imaging (MRI) techniques to assess neural representations of devel opment in both healthy and abnormally developing populations. A novel face emotion stimulus set, designed to assess distinct dimensions of facial emotion, particularly to assess the e ect of averted faces, is introduced in a pilot functional MRI study of an adult cohort. Results from this pilot study show that interactions between face direction and emotion can infuence which brain areas are recruited for emo- tion processing, suggesting that the neural correlates of judging facial emotion content are modulated by face direction. Facial emotion perception was assessed as a neural task to investigate dimensions of emotion processing, and emotion processing development, in a group of children and adolescents. A number of correlations were found between dimensions of the task and developmental measures such as age, pubertal development and intelligence. In particular, intelligence was shown to be positively associated with the increasing utilization of regions associated with cognitive control, such as the prefrontal cortex. A voxel-based morphometry (VBM) study explored potential structural correlates of adolescent development. Age was found to correlate with changes in local brain regions, however pubertal development was shown to be a more accurate measure of those changes. A diusion tensor imaging assessment of white matter using fractional anisotropy has demonstrated important developmental di erences in white matter be- tween males and females over childhood and adolescence. Findings also suggest diff erent relationships between intelligence and white matter for males and females. Developmental Coordination Disorder, a common childhood disorder characterised by deficits in learning and automating motor skills, was assessed as an example of ab normal brain development. VBM was used to show that kinematic metrics of a simple visuomotor task correlated with regional grey matter volumes.

Ph.D., Faculty of Science, University of the Witwatersrand, 2011 / This study investigated the effect of exogenous melatonin administration on transient global cerebral ischemia and adult neurogenesis in adult male Sprague- Dawley rats. It also determined serum melatonin concentrations in all the experimental groups and established any effect of melatonin on estimated total granule cell numbers. Adult male Sprague-Dawley rats were divided into eight groups with each group consisting of 6 rats (n = 6). Post-induction time durations of 72 hours and 7 days was used. Single dose of 5 mg/kg exogenous melatonin was administered at each phases of 30 minutes before and after a 10 minutes transient bilateral occlusion of the common carotid arteries in the different groups, followed by reperfusion. Rats were anesthetized with 20 mg/kg of ketamine and 2.5 mls of blood was collected via cardiac puncture for estimation of serum melatonin concentration using commercially prepared radioimmunoassay ELISA kit. Free floating brain sections cut at 50 μm were immunostained for Ki-67, marker for proliferating cells. The total granule cell number in the dentate gyrus was estimated using the optical fractionator method on plastic embedded brain sections. Mean melatonin concentration (pg/mol) was 268.54 ± 28.73 (72 hours) and 277.83 ± 28.73 (7 days) compared to the sham control; 266.94 ± 37.6 and non surgical 262.96 ± 23.85 respectively. Differences in the concentration were not statistically significant (P<0.05). Histological finding indicated neuropil disruption with potentiation of restoration as the post ischemia days progressed in the melatonin administered groups. The estimated total granule cell number in the dentate gyrus of the hippocampus was not affected by exogenous melatonin administration. However, there was potentiation in proliferations of the neurogenic niche in the dentate gyrus of the hippocampus demonstrating a very strong indications that melatonin enhanced the generations of proliferating cells in adult male Sprague-Dawley rats.

Early life stress (ELS) leads to alterations in anatomy and function of the adult hippocampal dentate gyrus (DG), but the mechanisms by which these lasting changes occur have not been fully elucidated. We tested the hypothesis that the immediate decrease in cell proliferation and neurogenesis induced by stress is the key mediator of the negative long-term outcomes of ELS. First, we tested whether inhibition of cell proliferation during early life is sufficient to reproduce the ELS-induced reduction in adult DG neurogenesis. We demonstrate that targeting dividing stem cells for elimination during the first or third postnatal weeks leads to diminished adult neurogenesis and reduction of the stem cell pool. Also, we hypothesized that ELS leads to more persistent effects on DG function than stress later in life because of the stress-induced elimination of specific birth cohorts of DG granule cells (GCs) that have distinct functions. We tested whether different birth cohorts of DG GCs differ in function by assessing behavioral and stress response outcomes of pharmacogenetic elimination or optogenetic activation of adult GCs born during the first or third postnatal week. We demonstrate that dorsal GCs born during the first or third postnatal week may be involved in modulating exploratory and anxiety behavior, but that only third postnatal week born GCs stimulate HPA activity. These results suggest that mature DG GCs may differ in specific functions with birth date determining their functional role. Third, we directly assessed the effect of ELS on DG development to better understand the immediate effects of ELS on the DG and to identify other potential mediators of the long-term effects. We demonstrate that ELS using the limited bedding/nesting paradigm leads to developmental delay of the DG. The work presented in this dissertation contributes to our understanding of the mechanisms by which ELS produces lasting impairments in DG function and also to our knowledge of how DG GC function is specified.

Thesis (M.A.)--University of Delaware, 2009. / Principal faculty advisor: Anna Klintsova, Dept. of Psychology. Includes bibliographical references.