Assessments of cognitive function of schizophrenic patients using fMRI, ERP and LORETA

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Functional MRI, ERP, LORETA and can complement the time and spatial resolution of each other. The combination of functional MRI and LORETA is a strong method to evaluate information processing in schizophrenia. We focused on the two main systems ; visual processing system and working memory system. Visual sensory inputs are processed in occipitemporal regions through feedforwad and feedback interactions between top-down and bottom-up process. And then mapping between stimulus and responses can be governed in the working memory system in prefrontal cortex. Experimental tasks and summaries results of are as follows :Working memory systemAuditory oddball paradigm ; front-temporal dysfunction in passive auditory novelty discrimination.Response competition ; deteriorated central executive systemVisual Processing System in Occipitemporal RegionsFace, eyes, eye-movement recognition ; underactive in face processing in occipitemporal cortex, extrastriatelOveractive for eyes and moving-eyes in the amygdale, insula, and extrastriate cortex.Illusory contour perception ; Underactive in IC processing in extrastriate, overactive for IC in ACC and insula.Global-Local perception ; underactive in Global processing in right occipitemporal cortex, overactive in Local processing in left occipitemporal cortex and PFC. Left hemisphere overactive-right hemisphere underactive in schizophrenic patients.Deficient in perceptual integration during processing in the extrastriate cortex, which might consequently increase the loads needed in the higher processing in the prefrontal cortex. Furthermore, the patients might have different profiles of hemispheric functional laterality from healthy control subjects.