Author's School

Graduate School of Arts & Sciences

Author's Department/Program

Biology and Biomedical Sciences: Neurosciences


English (en)

Date of Award

January 2009

Degree Type


Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

John Csernansky


Medial Temporal Lobe Structure and Function by Meghana Sunil Karnik Doctor of Philosophy in Biology and Biomedical Sciences: Neuroscience) Washington University in St. Louis, 2009 Professor John G. Csernansky, Chairperson My main goal was to examine the relationship between brain structure and function, specifically medial temporal lobe structure and episodic memory, in various groups of subjects who had schizophrenia, were at risk for schizophrenia because of genetic and disease influences, or who were healthy, in order to explore the influence of genetic and disease influences on brain structure-function relationships. Most of what is known about the neural structures thought to subserve episodic memory has been gleaned from studies of experimental lesions in animals, traumatic brain injury in humans, functional activation in healthy individuals, and age-related changes in specific structure-function relationships. By comparison, there has been a paucity of research on the variability of normative structure-function relationships and how such relationships might be influenced by disease. In conducting this work, I began with the assumption that medial temporal lobe structure-function relationships would be influenced by genetic factors. Thus, I chose to study the relationship between medial temporal lobe structure and episodic memory performance in the context of a disease known to have a strong genetic basis, namely schizophrenia. Moreover, schizophrenia has been frequently associated with altered medial temporal lobe structure and deficits in episodic memory. In this project, I subdivided the medial temporal lobe into two structural groupings - the hippocampus and the parahippocampal gyrus: PHG) and its subregions: entorhinal cortex, perirhinal cortex, and parahippocampal cortex: ERC, PRC and PHC. respectively). The subdivision of the PHG into its subregions was novel, and required the development of new methods for cortical assessment and parcelation. The specific aims of this project were: 1. To collect cognitive data and high resolution MR scans in groups of individuals with schizophrenia, healthy controls, and their siblings. 2. To extract a measure of episodic memory performance by selecting measures from the cognitive testing that assesses episodic memory. 3. To make measurements of hippocampal volume and the volume and thickness of the parahippocampal gyrus and its subregions. 4. Using a combined database of cognitive and structural data, to examine the relationship between medial temporal lobe structure and episodic memory performance in health and disease.


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