Source modelling of the P300 with variation of probability in two modalities using the dipole localization method

摘要: Available evidence suggests that the P300, an endogenous activity believed to be index of cognitive activity, is comprised functionally distinct multiple sources overlap spatially and temporally. Specifically, two questions are addressed in present thesis. Is P300 a reflection more than one neural source, if so, these indexing processes? The classic oddball paradigm was used with visual auditory stimuli occurring at levels probability. This design since literature variables may independently influence subcomponents therefore distinguish them. As well, reflects unitary source processing, then this should invariant across sensory modalities. A spatio-temporal dipole localization modelling procedure applied data determine whether single or varied as experimental modality, task probability were varied. rationale produce different results conditions. models equivalent dipoles head four-sphere volume conductor.The model employs least-squares iterative compare observed electrical fields those produced by assumed spherical conductor. While has necessary limitations, suggest it useful determining multiple, distributed comprise P300. Furthermore, demonstrate components distinct, which involved processing information about frequency events. It not clear target nontarget events processed sources. concluded umbrella component actually manifestation modes space time.