Dokument: Connectivity and Morphology of the Primate Brain

Titel:	Connectivity and Morphology of the Primate Brain
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=15657
URN (NBN):	urn:nbn:de:hbz:061-20100921-065528-9
Kollektion:	Dissertationen
Sprache:	Englisch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Reid, Andrew [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 6,79 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 05.07.2011 / geändert 05.07.2011
Stichwörter:	cortical connectivity, cortical thickness, cortical morphometry, cortical hierarchies, cerebral microangiopathy
Dewey Dezimal-Klassifikation:	100 Philosophie und Psychologie » 150 Psychologie
Beschreibung:	Modern neuroscientific research is built upon the solid foundation of over a century of pioneering efforts by anatomists, physiologists, physicians, surgeons, and more recently physicists, mathematicians, and computer scientists. The study of the neocortex – its structural organization and function – has proven a particularly difficult undertaking, and yet it may be fundamental to the understanding of human cognition, as well as neurological pathologies such as the loss of memory, sensation, motor function, and various forms of dementia. This dissertation focuses on both the structure and function of cortex using a number of distinct approaches. Firstly, drawing on graph and game theory, I present a novel formulation of the Shapley value, originally devised to analyze economic systems, to assess the degree to which individual vertices in a graph (representing connected cortical regions), contribute to the global connectivity of that graph. Shapley values were calculated for both intact and lesioned networks, obtained from macaque tract tracing literature, to demonstrate their utility for analyzing real cortical networks, and predicting the effects of insults to these networks. The Shapley value is compared to existing graph measures of cortical networks, demonstrating a fair degree of covariance – but not complete redundancy – particularly with the betweenness centrality measure. Secondly, I present an extension of the cortical hierarchy idea, first presented by Felleman and Van Essen (1991), which associates the anatomical patterns of cortical projections with their position in a functional hierarchy. A novel optimization framework is described, which uses continuous scales and ranges of values as constraints which define hierarchical relationships. The results of this optimization produce a hierarchy which is optimal, but which still has a number of constraint violations, corresponding to a number of regions which may be interesting for future anatomical investigation. Finally, a new measure based upon cell counting techniques, called the SLN%, is considered as a novel constraint for the optimization. Thirdly, I present the results from morphometric analyses of a large cohort of elderly adults with symptomatic small vessel disease, called the Radboud University Nijmegen Diffusion tensor- and Magnetic resonance imaging Cohort (RUN-DMC). Cortical surface representations of 485 subjects were obtained from structural MRI scans, and analyzed for the effects of age, sex, hemisphere, and white matter lesion volume, both as whole-surface and region-of-interest analyses. A distinct pattern of age-related cortical thinning was observed, which was greatest in prefrontal cortex, lateral and medial temporal cortex, and parts of primary visual and primary auditory cortex. The relationship of white matter lesion volume with cortical thickness was investigated across three age groups, indicating a strong negative correlation in most Brodmann areas for adults aged 60-85, as well as two paradoxical positive correlation in motor and sensory association regions. Fourthly, and finally, I present a novel method for assessing the degree to which an interregional projection is compromised by a white matter lesion, based upon diffusion-weighted MRI probabilistic tractography. Preliminary results from this method indicate that connectivity for long-range projections is difficult to detect using this technique; however, ways in which to resolve this issue are discussed. In light of the above research, I conclude by discussing the implications for clinical and basic research, and illustrate a number of future research prospects.
Lizenz:	Urheberrechtsschutz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Psychologie » Experimentelle Biologische Psychologie
Dokument erstellt am:	21.09.2010
Dateien geändert am:	05.07.2011
Promotionsantrag am:	02.07.2010
Datum der Promotion:	02.07.2010