High-Density Recording and Topographic Analysis of the Auditory Oddball Event-Related Potential in Patients with Schizophrenia

Background: Prior research has shown reductions of the N1, N2, and P300 auditory event-related potential (ERP) components in schizophrenic patients. Most studies have shown a greater P300 reduction in left versus right temporal leads in schizophrenic patients. These studies were done with sparse electrode arrays, covering re-stricted areas of the head, thus providing an incomplete representation of the topographic field distribution. Methods: We used a 64-channel montage to acquire auditory oddball ERPs from 24 schizophrenic patients and 24 controls subjects. The N1, P2, N2, P300, and N2 difference (N2d) amplitudes and latencies were tested for group and laterality differences. Component topographies were mapped onto a three-dimensional head model to display the group differences. Results: The schizophrenic group showed reduction of the N1 component, perhaps reflecting reduced arousal or vigilance, but no N1 topographic difference. An N2d was not apparent in the schizophrenic patients, perhaps re-flecting severe disruption in neural systems of stimulus categorization. In the patients, the P300 was smaller over the left temporal lobe sites than the right. Conclusions: The increased ERP spatial sampling al-lowed a more complete representation of the dipolar nature of the P300, which showed field contours consistent with neural sources in the posterior superior tempora