O'Donnell B F, Hokama H, McCarley R W, Smith R S, Salisbury D F, Mondrow E, Nestor P G, Shenton M E
Department of Psychiatry (116A), Brockton VA Medical Center, Harvard Medical School, MA 02401.
Int J Psychophysiol. 1994 Aug;17(3):219-31. doi: 10.1016/0167-8760(94)90065-5.
The effects of task demands and stimulus probability on the N1 and P2 components of the auditory event-related potential (ERP) to non-target stimuli were investigated in normal and medicated schizophrenic subjects. Subjects either read a book while tones were presented, or counted the rare (low probability) tones in an auditory oddball paradigm. The mismatch negativity to rare tones in the reading condition was present, and did not differ between groups. N1 amplitude was smaller in schizophrenic patients in all conditions. When subjects counted the rare tones, the amplitude and latency of P2 increased. This task-related effect on P2 was much greater in control than in schizophrenic subjects. Difference ERPs were used to better characterize the effect of task demands by subtracting the ERP in the reading condition from the ERP in the counting condition. The difference ERP consisted of a negative deflection at 182 ms, and a positive deflection at 276 ms, which were both reduced in schizophrenic subjects. N2 and P3 amplitude to target stimuli were reduced in patients as well, but these abnormalities were uncorrelated with N1 and P2 abnormalities to non-target stimuli. Despite automatic registration of stimulus mismatch, and normal processing speed, patients showed deficient task-related modulation of processing to both non-target and target stimuli. Reduction of N1 amplitude in schizophrenia occurs regardless of task demands, and may reflect a chronic, early-stage disturbance in information processing.
在正常受试者和药物治疗的精神分裂症患者中，研究了任务要求和刺激概率对非目标刺激的听觉事件相关电位（ERP）的N1和P2成分的影响。受试者要么在呈现音调时读书，要么在听觉oddball范式中计数罕见（低概率）音调。在阅读条件下，对罕见音调的失配负波存在，且两组之间无差异。在所有条件下，精神分裂症患者的N1波幅较小。当受试者计数罕见音调时，P2的波幅和潜伏期增加。与精神分裂症患者相比，对照组中这种与任务相关的P2效应要大得多。通过从计数条件下的ERP中减去阅读条件下的ERP，使用差异ERP来更好地表征任务要求的影响。差异ERP包括182毫秒时的负向偏转和276毫秒时的正向偏转，这两种偏转在精神分裂症患者中均减小。患者对目标刺激的N2和P3波幅也降低，但这些异常与对非目标刺激的N1和P2异常无关。尽管刺激失配能自动记录且处理速度正常，但患者对非目标和目标刺激的处理均表现出与任务相关的调制不足。精神分裂症患者的N1波幅降低与任务要求无关，可能反映了信息处理中的慢性早期干扰。
