Tan Hao-Yang, Choo Wei-Chieh, Fones Calvin S L, Chee Michael W L
Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Republic of Singapore.
Am J Psychiatry. 2005 Oct;162(10):1849-58. doi: 10.1176/appi.ajp.162.10.1849.
Working memory, a critical cognitive capacity that is affected in schizophrenia, can be divided into maintenance and manipulation processes. Previous behavioral research suggested that manipulation is more affected than maintenance in patients with chronic schizophrenia. In this study of first-episode schizophrenia patients, the authors evaluated the extent to which the two working memory processes are affected early in the course of schizophrenia.
Study subjects were 11 first-episode schizophrenia patients and 11 matched healthy comparison subjects. Each group performed two verbal working memory tasks while undergoing functional magnetic resonance imaging. One task required maintenance of information; the other required manipulation of information in addition to maintenance.
Under behaviorally matched conditions, both groups activated a predominantly left-sided frontal-parietal network. The manipulation plus maintenance task elicited activation of greater magnitude and spatial extent. With both tasks, patients showed less bilateral dorsolateral prefrontal cortex activation and greater ventrolateral prefrontal cortex activation, relative to the comparison subjects. A group-by-task interaction was observed for activation at the left dorsolateral and ventrolateral prefrontal cortex. The increase in activation when patients engaged in the manipulation plus maintenance task was disproportionately less in the dorsolateral prefrontal cortex and greater in the ventrolateral prefrontal cortex.
These functional neuroanatomical findings add support to earlier suggestions that manipulation of information is selectively more affected than maintenance of information in persons with schizophrenia. They also suggest the presence of interacting regions of dysfunctional and compensatory prefrontal responses in the dorsolateral and ventrolateral prefrontal cortex, respectively, that are more prominent when information is manipulated. This disrupted prefrontal network is present relatively early in the course of schizophrenia.
工作记忆是一种在精神分裂症中会受到影响的关键认知能力，可分为维持和操作过程。先前的行为研究表明，慢性精神分裂症患者的操作过程比维持过程受到的影响更大。在这项针对首发精神分裂症患者的研究中，作者评估了精神分裂症病程早期这两种工作记忆过程受影响的程度。
研究对象为11名首发精神分裂症患者和11名匹配的健康对照者。每组在进行功能磁共振成像时执行两项言语工作记忆任务。一项任务要求维持信息；另一项任务除了维持信息外，还要求对信息进行操作。
在行为匹配的条件下，两组均激活了主要位于左侧的额顶网络。操作加维持任务引发的激活在幅度和空间范围上更大。在两项任务中，与对照者相比，患者双侧背外侧前额叶皮质激活较少，腹外侧前额叶皮质激活较多。在左侧背外侧和腹外侧前额叶皮质的激活上观察到了组间任务交互作用。患者在进行操作加维持任务时，背外侧前额叶皮质激活的增加不成比例地较少，而腹外侧前额叶皮质激活的增加较多。
这些功能性神经解剖学发现支持了早期的观点，即精神分裂症患者中信息的操作比信息的维持受到的选择性影响更大。它们还表明，背外侧和腹外侧前额叶皮质分别存在功能失调和代偿性前额叶反应的相互作用区域，在信息被操作时更为突出。这种前额叶网络的破坏在精神分裂症病程中相对较早出现。
