Lencz Todd, Bilder Robert M, Turkel Elihu, Goldman Robert S, Robinson Delbert, Kane John M, Lieberman Jeffrey A
Department of Psychiatry, the Zucker Hillside Hospital, North Shore-Long Island Jewish Health System, Glen Oaks, NY, USA.
Arch Gen Psychiatry. 2003 Mar;60(3):238-43. doi: 10.1001/archpsyc.60.3.238.
Deficits in working memory (WM) have been reported in patients with schizophrenia, but WM is a complex construct dependent on several subprocesses, including input representation (perceptual competency) and holding stimuli on-line (maintenance). A visual delayed match-to-sample task (DMST) was developed to isolate perceptual competency from maintenance during delays. It was hypothesized that patients in the first episode of schizophrenia would exhibit dissociable deficits in both WM domains.
Performance on the DMST was assessed in 57 patients in the first episode of schizophrenia or schizoaffective disorder and 22 healthy comparison subjects. In phase 1 of the DMST, a complex visual stimulus (target) was followed immediately by a forced choice between 2 test stimuli, and item difficulty (differences between the test stimuli) was titrated until each subject achieved a consistent accuracy (80%-90%) in this no-delay condition. In phase 2, a delay of 4 or 8 seconds with a mask of randomly illuminated pixels was introduced between target and test stimuli; test stimuli were fixed in difficulty level based on phase 1 titration. Main outcome measures were mean item difficulty attained in the no-delay condition and mean accuracy in matching after delay.
Compared with controls, patients attained a lower level of difficulty in the no-delay condition (P =.001) and significantly lower accuracy with delay (P =.002).
Deficits in both domains of WM suggest abnormality in the posterior and prefrontal cortexes. These deficits can be observed in a task involving complex visual pattern stimuli using only a brief delay and are present even in unmedicated patients in the first episode of illness.
已有报道称精神分裂症患者存在工作记忆（WM）缺陷，但WM是一个复杂的概念，依赖于多个子过程，包括输入表征（感知能力）和在线保持刺激（维持）。为了在延迟期间将感知能力与维持能力区分开来，开发了一种视觉延迟匹配样本任务（DMST）。据推测，首发精神分裂症患者在这两个WM领域都会表现出可分离的缺陷。
对57例首发精神分裂症或分裂情感性障碍患者和22名健康对照者进行了DMST测试。在DMST的第1阶段，一个复杂的视觉刺激（目标）之后紧接着是在2个测试刺激之间进行强制选择，并且调整项目难度（测试刺激之间的差异），直到每个受试者在这种无延迟条件下达到一致的准确率（80%-90%）。在第2阶段，在目标刺激和测试刺激之间引入4秒或8秒的延迟，并伴有随机点亮像素的掩蔽；根据第1阶段的调整确定测试刺激的难度水平。主要观察指标是在无延迟条件下达到的平均项目难度以及延迟后匹配的平均准确率。
与对照组相比，患者在无延迟条件下达到的难度水平较低（P =.001），延迟后的准确率显著较低（P =.002）。
WM两个领域的缺陷表明后额叶和前额叶皮质存在异常。这些缺陷可以在仅使用短暂延迟的涉及复杂视觉模式刺激的任务中观察到，并且即使在首发未用药的患者中也存在。
