The study of pathophysiological mechanism for the subcortical dementia- an evaluation using event-related potentials tomography

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To evaluate the pathophysiological changes in subcortical dementia, electrical filed of the event-related potentials were analyzed. As the fundamental study, we examined the effect of task relevance and the novelty of P3a components in an auditory study. Our data suggest that the characterization of novelty P300 may depend on the mental resources that can be devoted to novel stimuli during parallel processing.After the fundamental study, we evaluated the characteristics of information processing disturbance in patients with vascular dementia (VaD) using auditory oddball and 4-tone paradigms. The data suggest that the characteristics of mental dysfunction in mild VaD patients do not only depend on abnormal information processing speed but also abnormal mental resource allocation.The 3rd study is the evaluation of pathophysiological mechanism for the Parkinson's disease as subcortical dementia. Event-related potentials topography produced by novel and target stimuli was used to detect dysfunction of mental switching (perseveration) in Parkinson's disease Parkinson's disease patients (PDPs). Our findings suggest that decreased mental switching causes lack of novelty P3 habituation in PDPs and that this is related to learning disability based on dysfunction of frontal lobe and basal ganglia.Finally, we investigated whether early information processing for auditory sensory input would be hindered in PDPs. The data indicated that there are dysfunction both of automatic and controlled processing in the information processing for auditory sensory input in the PDP.