Cairo Tara A, Woodward Todd S, Ngan Elton T C
Department of Research, Riverview Hospital, Coquitlam, Canada.
Biol Psychiatry. 2006 Apr 15;59(8):740-6. doi: 10.1016/j.biopsych.2005.08.009. Epub 2005 Oct 17.
Working memory deficits are a cardinal feature of schizophrenia that contribute to social and occupational dysfunction.
We used functional magnetic resonance imaging to compare the response to varying task demands during the performance of an item recognition task. Study design and analysis procedures were optimized for the detection of load dependent activity during the encoding phase of working memory.
At the lowest load conditions the schizophrenia group performed as well as controls, however to achieve this equivalent performance the schizophrenia group had a significantly higher magnitude of activation compared to the controls. At the higher load conditions, the magnitude of activation between groups became more similar and we began to see performance deficits in the schizophrenic group.
These results suggest that patients with schizophrenia have decreased efficiency in the cognitive processes that underlie the early encoding phase of this task. For lower demand tasks, patients with schizophrenia can compensate for decreased efficiency by working harder to achieve equivalent performance. Encoding utilizes attentional and perceptual cognitive operations that are likely common to many other cognitive tasks; therefore, inefficiency may underlie the deficits observed in a wide range of cognitive tasks in schizophrenia compared to healthy controls.
工作记忆缺陷是精神分裂症的一个主要特征，会导致社会和职业功能障碍。
我们使用功能磁共振成像来比较在执行项目识别任务期间对不同任务需求的反应。研究设计和分析程序针对工作记忆编码阶段负荷依赖性活动的检测进行了优化。
在最低负荷条件下，精神分裂症组的表现与对照组一样好，然而，为了达到同等表现，与对照组相比，精神分裂症组的激活程度明显更高。在较高负荷条件下，两组之间的激活程度变得更加相似，并且我们开始在精神分裂症组中看到表现缺陷。
这些结果表明，精神分裂症患者在该任务早期编码阶段所依赖的认知过程中效率降低。对于需求较低的任务，精神分裂症患者可以通过更加努力地工作来弥补效率下降，以达到同等表现。编码利用了许多其他认知任务可能共有的注意力和感知认知操作；因此，与健康对照组相比，效率低下可能是精神分裂症患者在广泛认知任务中观察到的缺陷的潜在原因。
