No description available.

Thesis (B.Med.Sc.Hons. 1970) from the Department of Psychology, University of Adelaide.

Thesis (Ph.D.)--Australian National University, 2005.

Thesis (Ph.D.)--University of Alberta, 1997. / Submitted to the Faculty of Graduate Studies and Research in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Department of Psychology. Also available online.

No description available.

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor off Philosophy Johannesburg, 2015 / Background Objective volumetric assessment of white matter in children with HIV involves post M processing, while corpus callosum (CC) thickness measurement on midMsagittal MRI may represent a rapid surrogate marker. Aim To determine whether the thickness of the CC on midMsagittal MRI can be used as a surrogate marker of brain volume in children with HIV Mrelated brain disease and in appropriate controls and to determine whether thickness at particular locations correlates with mental developmental scores and laboratory markers of immunity. Methods A retrospective analysis of 33 children with HIV Mrelated neurology(range 7 M 49 months; median31 months; mean 30 months; 16 boys and 17 girls) and matched controls (range 13 – 48 months; median 34 months; mean 32 months; 6 boys and 5 girls) was performed. A custom software tool imported sagittal MRI images, divided the midline CC contour into 40 segments and measured the thickness of each segment as well as the length of the CC. Brain volume (total brain volume (TBV); white matter volume (WMV);grey matter volume (GMV)) was determined using MATLAB and Statistical Parametric Mapping software. Overall and segmental CC mean and maximum thickness and CC length were checked for correlation with brain volume, Griffiths mental development scores(GMDS) and laboratory parameters. Results Griffiths scores in patients were ‘low average’ (mean Griffiths general quotient (GQ) of 84, range 72 – 101; ‘locomotor’ 84, range 59 – 116; ‘language’ 80; range57 –118). There was no statistical difference in overall and regional CC thickness, CC length, TBV, GMV and WMV between patients and controls. Significant correlation was found in patients for the premotor CC mean with age (p = 0.04). Other significant correlations of CC measurements and laboratory / clinical parameters were the prefrontal CC max with in adir CD4 (p=0.046)(+vecorrelation); motor CC max with GQ (p=0.028) (Mve!correlation) and CC length with CD4(p=0.04) (Mve correlation). Significant correlations between CC thickness and brain volume were found in patients and controls for the CC mean and TBV (p=0.049)(+ve correlation);premotor CC mean and TBV (p=0.039)(+ve correlation); sensory CC mean and TBV (p=0.022)(+ve correlation); prefrontal CC max and WMV (p=0.019)(+ve correlation); premotor CC mean and WMV (p=0.019)(+ve correlation and for the premotor CC max and WMV (p=0.023)(+ve correlation). Conclusion: This research met its objectives in demonstrating a statistically significant, albeit weak, correlation between CC thickness and brain volume in patients and controls, even though patients were not shown to have significantly diminished brain volumes as compared to controls.

Thesis (Ph. D.)--University of Chicago, Department of Psychology, December 1999. / Includes bibliographical references. Also available on the Internet.

Long-term potentiation (LTP), a long-lasting enhancement of synaptic efficacy, is believed to be the mechanism by which memory storage occurs in the brain. Several studies have shown that LTP can be induced in various neural sites, not only by electrical stimulation, but also as a result of behavioural modifications. It has previously been shown that LTP in the primary motor cortex accompanies motor skill learning. One study showed that potentiation occurred following training on a lateralised skilled reaching task. In this task, animals are trained to use only one paw to grasp a small food pellet. An interesting finding that has been uncovered from these studies is that, although only one hemisphere actively participates in the task (the trained hemisphere), the other hemisphere (untrained hemisphere) also shows potentiation. This has led to the hypothesis that the corpus callosum is involved in the transfer of information from one hemisphere to another during training on the reaching task. The nature of this communication, however, is unknown. Two possibilities were considered. The first was that the callosum transfers information that allows the animal to maintain its balance while the reaching paw is elevated. Careful observation of videorecording made while animals performed the task however, failed to reveal any deficits in balance in animals that had undergone a callosal transection. A second possibility is that the corpus callosum transfers information about the task from the trained to the untrained hemisphere such that, even though it does not actively participate in the task, the untrained paw may "know" how to perform above chance level. Analysis of the rate of successful reaching with the untrained paw revealed no advantage for normal animals over transected animals. Work is however, currently underway to increase the number of animals in the study in order to obtain a more conclusive result. / Thesis / Master of Science (MS)

Thesis advisor: Ellen Winner / Recent studies have shown differences between several structures in the brains of professional level musicians and non-musicians. Professional musicians form an ideal group to study changes in the human brain due to the unique abilities required of them. Since many musicians begin training at a young age, it is assumed that these differences are attributable to intense, early experience brought on by the cognitive and motor demands of music training. However, it remains to be seen whether these structural differences are due to changes brought on by experience or preexisting ones which draw children to music lessons. Using magnetic resonance images, I compared the size of the corpus callosums in two groups of children who ranged between the ages of five and seven, one just beginning music lessons and another not beginning music lessons. I also compared the groups in terms of their performance on a finger tapping test for differences in speed and accuracy. A second set of comparisons of callosal size was conducted between nine-to-eleven-year-olds who had been taking music lessons for at least a year and those who had not. Differences in the five-to-seven-year-olds were seen in the anterior corpus callosum corrected for brain volume between the musician and non-musician groups. Differences in accuracy of finger tapping were seen between the musicians and non musicians, as well as between those in the musician group who had received less than sixteen or twenty-five weeks of training versus those who had received less. These findings indicate that while musicians start out with at least one slightly larger measure of corpus callosum size, differences in finger skill tend to develop slowly. / Thesis (BA) — Boston College, 2004. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Psychology. / Discipline: College Honors Program.

Heparan sulphate proteoglycans (HSPGs) are a family of molecules that are found on the surface of cells or in the extracellular matrix, where they are involved in regulating key signalling events required for normal mammalian brain development. It is thought that specificity of HSPGs for particular signalling processes is encoded by their heparan sulphate (HS) sugar side chains, which can be modified post-translationally to yield huge variation in HS structure. Different sulphation patterns are generated by the action of the heparan sulphate sulfotransferases (HSTs) and sulfatase enzymes, which add or remove sulphate groups to specific positions on residues of the HS side chains. Depending on the expression of these enzymes and the resulting heparan sulphate ‘code’, it is proposed that cells are then able to regulate signals they receive and send in the ligand rich extracellular environment of the developing forebrain. Hs6st1 and Hs2st catalyse 6-O and 2-O HS sulphation, respectively. Following loss of either of these two HSTs, commissural tracts including the corpus callosum fail to develop normally during late mouse embryogenesis. The telencephalic midline environment is perturbed, with a striking mis-positioning of glial cell populations that normally act to guide axons towards the contralateral hemisphere. Too many radial glial cells at the glial wedge (GW) migrate towards the indusium griseum (IG) in mutant embryos. The running hypothesis to explain this phenotype is a change in critical signalling pathways required to set up the correct midline glia environment, such as Fgf8/ERK signalling which has already been identified as up-regulated at the Hs6st1-/- corticoseptal boundary (CSB). In order to further study what changes are occurring at the developing midline of HST-/- embryos compared to WT, we took a hypothesis free approach using RNA-sequencing analysis. RNA extracted from dissected midline regions of WT, Hs2st-/- and Hs6st1-/- mouse embryos at E16.5 was sent for sequencing, and a list of differentially expressed genes obtained. Overall we find few differentially expressed genes at the Hs6st1-/- midline compared to WT. At the Hs2st- /- midline there are a larger number of differentially expressed genes. Following validation studies, we find a significant and specific increase in Fgf17 protein distribution at the CSB of Hs2st-/- embryos compared to WT at E14.5. The results suggest the hypothesis that Hs2st’s normal role is to regulate Fgf17 protein distribution to limit exposure of GW radial glia cells to this translocation signal. When 2-O HS sulphation is lost then in Hs2st-/- embryos, ectopic Fgf17 signalling induces aberrant glia migration which ultimately prevents callosal axons from crossing the telencephalic midline to form the corpus callosum. To test this hypothesis, we used ex vivo slice culture experiments and showed ectopic Fgf17 protein expression is sufficient to trigger precocious translocation of midline glia in WT CSB, phenocopying the glia behaviour of Hs2st-/- embryos. Also consistent with the hypothesis, the Hs2st-/- glia phenotype can be rescued by addition of an FgfR1 inhibitor which reduces number of translocated glia cells. From these results we find for the first time that 2-O sulphated HS plays a remarkably specific role in regulating Fgf17-mediated translocation of midline glia cells at the developing mammalian telencephalic midline.