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Data-Driven Neuroanatomical Subtypes In Various Stages Of Schizophrenia: Linking Cortical Thickness, Glutamate, And Language Functioning, Liangbing Liang

Electronic Thesis and Dissertation Repository

The considerable variation in the spatial distribution of cortical thickness changes has been used to parse heterogeneity in schizophrenia. We aimed to recover a ‘cortical impoverishment’ subgroup with widespread cortical thinning. We applied hierarchical cluster analysis to cortical thickness data of three datasets in different stages of psychosis and studied the cognitive, functional, neurochemical, language and symptom profiles of the observed subgroups. Our consensus-based clustering procedure consistently produced a subgroup characterized by significantly lower cortical thickness. This ‘cortical impoverishment’ subgroup was associated with a higher symptom burden in a clinically stable sample and higher glutamate levels with language impairments in …

Inviting Hallucinatory Percepts During Speech-Listening To Detect Cognitive Changes In Early Psychosis, Ana-Bianca Popa

Electronic Thesis and Dissertation Repository

Treatment outcomes for people with schizophrenia are more favourable if treatment starts early in the course of the disorder. Current detection methods lack specificity and do not make use of cognitive markers. We presented individuals experiencing a first episode of psychosis (FEP) and matched control participants with acoustically degraded meaningful and matched nonsense sentences to examine the degree to which people reported words that were not actually presented. Intrusion errors were counted when reported words were unrelated to words in the original sentence. Intelligibility (measured as words reported correctly) did not differ between groups but intrusion errors were more frequent …

Measuring Brain Serine With Proton Magnetic Resonance Spectroscopy At 3.0 Tesla, Homa Javadzadeh

Electronic Thesis and Dissertation Repository

Proton magnetic resonance spectroscopy (MRS) non-invasively measures regional human brain chemistry in vivo, providing concentration estimates for several metabolites in a pre-selected region of interest. MRS has been applied to investigations of disease-related metabolic and neurochemical alterations in schizophrenia since the early 90’s.

The objective of this research is to implement a metabolite-selective MRS method to quantify endogenous concentrations of human brain serine. Serine is a naturally-occurring amino acid and an important co-modulator of the N-Methyl D-aspartic Acid (NMDA) glutamate receptor. Glutamate abnormalities have been implicated in the pathophysiology of schizophrenia, especially its so-called negative and cognitive symptoms, which can …

Addressing Very Short Stimulus Encoding Times In Modeling Schizophrenia Cognitive Deficit, Colleen D. Cutler

Electronic Thesis and Dissertation Repository

It is well known that encoding times in persons with schizophrenia are longer than those of normal controls. Neufeld and others have argued that this is the consequence of additional subprocesses being executed during the encoding process in the case of schizophrenia. In general they expressed an encoding time as the sum of $k^{\prime}$ independent exponentially-distributed subprocesses, each executed with rate $v$. A troubling consequence of their application of this model to real data was that under some circumstances some individuals appeared to encode instantaneously. This was accommodated in Neufeld et al. by placing a Poisson distribution on …