Clinical Neuroscience Division, Laboratory of Neuroscience, VA Boston Healthcare System-Brockton Division, Department of Psychiatry, Harvard Medical School, Brockton, MA, United States.
Schizophr Res. 2013 May;146(1-3):95-102. doi: 10.1016/j.schres.2013.01.015. Epub 2013 Feb 19.
P300 deficits in schizophrenia patients are well established, especially in the auditory modality. Several studies have also reported P300 abnormalities in schizophrenia in visual tasks, but these findings are inconsistent. Furthermore, reports on P300 in visual modality in prodromal subjects are very limited. While P300 indexes relatively late and complex cognitive functions such as context updating in working memory, sensory-evoked components such as the P1/N1 primarily index early stages of perceptual processing. Several previous studies suggest that P300 reduction in schizophrenia patients may be dissociable from these earlier components. Therefore, in this study, we measured the P300 component as well as the P1/N1 in a visual oddball paradigm in prodromal subjects and first episode schizophrenia patients, and compared them with those of healthy controls.
Visual P300 and P1/N1 were obtained from prodromal (PRO, n = 23), first episode schizophrenia patients (SZ, n = 17), and healthy control subjects (HC, n = 31), who silently counted infrequent target stimuli ("X") amid standard stimuli ("Y") presented on the screen while 64-channel EEG was recorded.
Both PRO and SZ subjects showed reduced P300 amplitudes and delayed P300 peak latencies in comparison to control subjects. On the other hand, N1 amplitude was significantly reduced only in SZ but not in PRO. Increased severity of positive symptoms was significantly associated with smaller P300 amplitude in PRO.
These results suggest that visual P300 is affected already at the prodromal stage and could be a marker of the prodromal phase of schizophrenia.
精神分裂症患者的 P300 缺陷已得到充分证实，尤其是在听觉模态中。几项研究还报告了精神分裂症在视觉任务中 P300 的异常，但这些发现并不一致。此外，关于前驱期受试者视觉模态中 P300 的报告非常有限。虽然 P300 指数相对较晚和复杂的认知功能，如工作记忆中的上下文更新，但感觉诱发的成分，如 P1/N1，主要指数知觉处理的早期阶段。几项先前的研究表明，精神分裂症患者的 P300 减少可能与这些早期成分分离。因此，在这项研究中，我们在前驱期受试者和首发精神分裂症患者中测量了视觉Oddball 范式中的 P300 成分和 P1/N1，并将其与健康对照组进行了比较。
视觉 P300 和 P1/N1 是从前驱期（PRO，n=23）、首发精神分裂症患者（SZ，n=17）和健康对照组（HC，n=31）中获得的，他们在屏幕上呈现标准刺激（“Y”）时默默地对低频目标刺激（“X”）进行计数，同时记录 64 通道 EEG。
与对照组相比，PRO 和 SZ 受试者的 P300 振幅降低，P300 峰值潜伏期延迟。另一方面，只有 SZ 而不是 PRO 的 N1 振幅显著降低。阳性症状的严重程度增加与 PRO 中的 P300 振幅减小显著相关。
这些结果表明，视觉 P300 在前驱期已经受到影响，可能是精神分裂症前驱期的一个标志物。
