Boyd Jenna E, Patriciu Iulia, McKinnon Margaret C, Kiang Michael
Department of Psychiatry and Behavioural Neurosciences, McMaster University, Ontario L8S 4K1, Canada; St. Joseph's Healthcare Hamilton, Hamilton, Ontario L8N 3K7, Canada; Homewood Research Institute, Guelph, Ontario N1E 6K9, Canada.
St. Joseph's Healthcare Hamilton, Hamilton, Ontario L8N 3K7, Canada.
Schizophr Res. 2014 Sep;158(1-3):195-203. doi: 10.1016/j.schres.2014.06.018. Epub 2014 Jul 9.
The N400 event-related brain potential (ERP), a negative voltage deflection occurring approximately 400ms after onset of any meaningful stimulus, is reduced in amplitude when the stimulus is preceded by related context. Previous work has found this N400 semantic priming effect to be decreased in schizophrenia, suggesting impairment in using meaningful context to activate related concepts in semantic memory. Thus, N400 amplitude may be a useful biomarker of abnormal semantic processing and its response to treatment in schizophrenia. To help assess the validity of N400 amplitude as a longitudinal measure in schizophrenia, we evaluated its test-retest reliability. ERPs were recorded in sixteen schizophrenia patients who viewed prime words, each followed at 300- or 750-ms stimulus-onset asynchrony (SOA) by a target that was either a related or unrelated word, or nonword. Participants' task was to indicate whether or not the target was a real word. They were retested on the same procedure one week later. Test-retest reliability was assessed by calculating Pearson's r and intraclass correlation coefficients (ICCs) across timepoints for N400 amplitudes for related and unrelated targets, at each SOA. Consistent with previous results, there were no significant differences between patients' N400 amplitudes for related and unrelated targets, at any SOA/timepoint combination. Pearson's r and ICCs for N400 amplitudes at Fz across timepoints were significant for both target types at each SOA (ranges: r 0.52-0.64, ICC 0.52-0.63; all p<.04). The results suggest potential utility of N400 amplitude as a longitudinal neurophysiological biomarker of semantic processing abnormalities in schizophrenia.
N400事件相关脑电位（ERP）是在任何有意义刺激开始后约400毫秒出现的负电压偏转，当刺激之前有相关背景时，其振幅会降低。先前的研究发现，精神分裂症患者的这种N400语义启动效应会减弱，这表明在利用有意义的背景激活语义记忆中的相关概念方面存在损害。因此，N400振幅可能是精神分裂症中异常语义加工及其对治疗反应的有用生物标志物。为了帮助评估N400振幅作为精神分裂症纵向测量指标的有效性，我们评估了其重测信度。对16名精神分裂症患者进行ERP记录，他们观看启动词，每个启动词之后在300毫秒或750毫秒的刺激起始异步（SOA）时出现一个目标词，该目标词要么是相关词、不相关词，要么是无意义词。参与者的任务是指出目标词是否为真实单词。一周后，他们按照相同程序进行重新测试。通过计算每个SOA下相关和不相关目标的N400振幅在各时间点之间的皮尔逊r系数和组内相关系数（ICC）来评估重测信度。与先前结果一致，在任何SOA/时间点组合下，患者相关和不相关目标的N400振幅之间均无显著差异。在每个SOA下，Fz处N400振幅在各时间点之间的皮尔逊r系数和ICC对两种目标类型均具有显著性（范围：r为0.52 - 0.64，ICC为0.52 - 0.63；所有p <.04）。结果表明，N400振幅作为精神分裂症语义加工异常的纵向神经生理生物标志物具有潜在效用。
