LORETA imaging of P300 in schizophrenia with individual MRI and 128-channel EEG

한글 요약

조현병 환자에서 인지적 사건관련전위인 P300의 발생원이 어디에 있고 어떻게 달라지는지를 살핀 연구입니다. 128채널 뇌파(EEG)와 개인별 MRI 기반 현실적 두부 모델을 결합한 저해상도 전자기 단층촬영(LORETA)으로 전류밀도 영상을 재구성하고, 이를 표준 공간으로 정규화한 뒤 복셀 단위 통계 지도화(SPM)로 환자군과 대조군을 비교했습니다. 정상인에서는 P300 발생원이 일관되게 좌측 상두정엽에 위치했지만 환자에서는 흩어져 있었고, 좌측 내측 측두엽과 하두정엽의 전류밀도가 감소한 반면 좌측 전전두엽과 우측 안와전두엽은 상대적으로 활성화되어 있었습니다. 좌측 두정측두 영역의 활성이 낮을수록 증상이 심한 경향도 있어, 조현병의 병태생리에 전두엽-측두엽 회로의 이상이 관여함을 시사합니다.

We investigated the characteristics of P300 generators in schizophrenics by using voxel-based statistical parametric mapping of current density images. P300 generators, produced by a rare target tone of 1500 Hz (15%) under a frequent nontarget tone of 1000 Hz (85%), were measured in 20 right-handed schizophrenics and 21 controls. Low-resolution electromagnetic tomography (LORETA), using a realistic head model of the boundary element method based on individual MRI, was applied to the 128-channel EEG. Three-dimensional current density images were reconstructed from the LORETA intensity maps that covered the whole cortical gray matter. Spatial normalization and intensity normalization of the smoothed current density images were used to reduce anatomical variance and subject-specific global activity and statistical parametric mapping (SPM) was applied for the statistical analysis. We found that the sources of P300 were consistently localized at the left superior parietal area in normal subjects, while those of schizophrenics were diversely distributed. Upon statistical comparison, schizophrenics, with globally reduced current densities, showed a significant P300 current density reduction in the left medial temporal area and in the left inferior parietal area, while both left prefrontal and right orbitofrontal areas were relatively activated. The left parietotemporal area was found to correlate negatively with Positive and Negative Syndrome Scale total scores of schizophrenic patients. In conclusion, the reduced and increased areas of current density in schizophrenic patients suggest that the medial temporal and frontal areas contribute to the pathophysiology of schizophrenia, the frontotemporal circuitry abnormality.