[原著］Abnormal Fronto-Temporal Network in First-Episode Schizophrenia Revealed by Low-Resolution Electromagnetic Tomography (LORETA) of P300 Auditory Event-Related Potentials
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The P300 component of auditory event-related potentials (ERPs) is an electrophysiological marker of cognitive operation. Previous studies had found dysfunction of the frontotemporal network in schizophrenia using P300 current density analysis. However, whether this abnormality is a primary effect of schizophrenia remains unclear, because chronic patients had been included in previous studies. In this study, P300 current density analysis was performed in 30 first-episode and drug-free schizophrenic patients and 30 normal controls. P300 was elicited using an auditory oddball paradigm. ERPs were recorded from 16 scalp electrodes. A new method of low-resolution electromagnetic tomography (LORETA) was applied to perform P300 current density analysis in this study. The cortical P300 sources were computed from grand average wave forms. A significant probability map of P300 cortical current density differences between two groups was constructed, based on the point-by-pomt t-test. The 3-D cortical current density map demonstrated activation of the bilateral fronto-temporal network as the major neural generator of the scalp-recorded P300 in control subjects. However, in schizophrenics, this activation was decreased as compared with control subjects. Furthermore, inter-group differences in P300 current density were more prominent over the left versus the right hemisphere. It is suggested that the dysfunction of the fronto-temporal network, especially over the left hemisphere, might be a primary effect of schizophrenia, possibly being involved in the mechanism of schizophrenia.