Comparison Of Brain Mechanisms Of Spatial Working Memory And Classification Of Various Mental Disorder

Working memory is a capacity-limited memory system for temporary storage and processing of information.As a subsystem of working memory,spatial working memory is responsible for processing spatial information,such as the spatial location of targets and the spatial location relationships between targets.Studies have shown that various mental disorders exhibit impaired spatial working memory,but few studies have compared the neural mechanisms of spatial working memory in patients with various mental disorders.To address this issue,present thesis uses behavioral and brain imaging data from open databases to investigate common and distinct brain mechanism when performing spatial working memory tasks among healthy and schizophrenic populations,bipolar disorder populations,and attention deficit hyperactivity disorder populations.In addition,three mental disorder populations were classified from healthy populations based on imaging data.The results of the behavioral data of the spatial working memory task showed that the spatial working memory ability of the schizophrenic population was significantly lower than that of the healthy population,and there was no significant difference in the spatial working memory ability of the bipolar disorder population,the attention deficit hyperactivity disorder population and the healthy population.The task state MRI data showed that the brain activation in the left cingulate gyrus,right superior frontal gyrus and right precentral gyrus during the probe phase of spatial working memory was significantly different in schizophrenia than in healthy subjects,and the strength of connections between some brain regions in the frontal lobe during this phase was lower than in healthy subjects.In the bipolar disorder population,there were brain regions with significantly different activation from the healthy population in the delay and probe stages of spatial working memory,and the strength of connections between some brain regions in the occipital lobe and between the occipital lobe and the parietal lobe were lower than those in the healthy population in these two stages.The brain regions with significant activation differences from healthy subjects during the target,delay,and probe phases of spatial working memory tasks were found in the frontal,parietal,occipital,and temporal lobes of the population with attention deficit hyperactivity disorder.Resting-state MRI data showed that in the visual network,fractional amplitude of low-frequency fluctuation were lower in the schizophrenia and bipolar disorder populations than in the healthy population,and regional homogeneity was lower in the three psychiatric disorder populations than in the healthy population.However,in the limbic network schizophrenia and bipolar disorder had higher fractional amplitude of low-frequency fluctuation,regional homogeneity and degree centrality than the healthy population.Using the above brain features obtained from the task state and resting state data analysis as classification features,the results of dichotomous classification of the healthy population and different mental disorder populations using support vector machines showed that the best classification results were obtained for the schizophrenia population with a maximum classification accuracy of 85%,the bipolar disorder population with a maximum classification accuracy of 80.08%,and the attention deficit hyperactivity disorder with the worst classification results with a maximum classification accuracy of 72.91%.In summary,this thesis used functional magnetic resonance imaging to reveal the differences in specific brain mechanisms between the three mental disorder populations and healthy populations in performing spatial working memory tasks,as well as the the intrinsic brain activity characteristics of the three mental disorder populations,and to suggest the significance of these brain characteristics in population classification.