Department of Psychiatry, Geneva University Hospitals and University of Geneva, Switzerland.
J Psychiatry Neurosci. 2012 Feb;37(2):95-105. doi: 10.1503/jpn.110033.
Earlier contributions have documented significant changes in sensory, attention-related endogenous event-related potential (ERP) components and θ band oscillatory responses during working memory activation in patients with schizophrenia. In patients with first-episode psychosis, such studies are still scarce and mostly focused on auditory sensory processing. The present study aimed to explore whether subtle deficits of cortical activation are present in these patients before the decline of working memory performance.
We assessed exogenous and endogenous ERPs and frontal θ event-related synchronization (ERS) in patients with first-episode psychosis and healthy controls who successfully performed an adapted 2-back working memory task, including 2 visual n-backworking memory tasks as well as oddball detection and passive fixation tasks.
We included 15 patients with first-episode psychosis and 18 controls in this study. Compared with controls, patients with first-episode psychosis displayed increased latencies of early visual ERPs and phasic θ ERS culmination peak in all conditions. However, they also showed a rapid recruitment of working memory-related neural generators, even in pure attention tasks, as indicated by the decreased N200 latency and increased amplitude of sustained θ ERS in detection compared with controls.
Owing to the limited sample size, no distinction was made between patients with first-episode psychosis with positive and negative symptoms. Although we controlled for the global load of neuroleptics, medication effect cannot be totally ruled out.
The present findings support the concept of a blunted electroencephalographic response in patients with first-episode psychosis who recruit the maximum neural generators in simple attention conditions without being able to modulate their brain activation with increased complexity of working memory tasks.
早期的研究已经记录了精神分裂症患者在工作记忆激活期间，感觉和与注意力相关的内源性事件相关电位（ERP）成分以及θ波段振荡反应的显著变化。在首发精神病患者中，此类研究仍然很少，且主要集中在听觉感觉处理上。本研究旨在探索首发精神病患者在工作记忆表现下降之前是否存在皮质激活的细微缺陷。
我们评估了首发精神病患者和健康对照组在成功执行改编后的 2 背工作记忆任务时的外源性和内源性 ERP 以及额部θ事件相关同步（ERS），其中包括 2 个视觉 n 背工作记忆任务以及Oddball 检测和被动注视任务。
本研究共纳入 15 名首发精神病患者和 18 名对照者。与对照组相比，首发精神病患者在所有条件下均显示早期视觉 ERP 和相位θ ERS 顶峰的潜伏期增加。然而，与对照组相比，他们在纯注意任务中也显示出工作记忆相关神经发生器的快速募集，这表现为在检测中 N200 潜伏期缩短和持续θ ERS 幅度增加。
由于样本量有限，我们没有对阳性和阴性症状的首发精神病患者进行区分。尽管我们控制了神经阻滞剂的总体负荷，但不能完全排除药物的影响。
本研究结果支持首发精神病患者的脑电图反应迟钝的概念，他们在简单注意条件下招募最大的神经发生器，而无法通过增加工作记忆任务的复杂性来调节大脑激活。
