Johnson Matthew R, Morris Nicholas A, Astur Robert S, Calhoun Vince D, Mathalon Daniel H, Kiehl Kent A, Pearlson Godfrey D
Olin Neuropsychiatry Research Center, The Institute of Living at Hartford Hospital, Hartford, CT, USA.
Biol Psychiatry. 2006 Jul 1;60(1):11-21. doi: 10.1016/j.biopsych.2005.11.012. Epub 2006 Feb 28.
Previous neuroimaging studies of working memory (WM) in schizophrenia, typically focusing on dorsolateral prefrontal cortex, yield conflicting results, possibly because of varied choice of tasks and analysis techniques. We examined neural function changes at several WM loads to derive a more complete picture of WM dysfunction in schizophrenia.
We used a version of the Sternberg Item Recognition Paradigm to test WM function at five distinct loads. Eighteen schizophrenia patients and 18 matched healthy controls were scanned with functional magnetic resonance imaging at 3 Tesla.
Patterns of both overactivation and underactivation in patients were observed depending on WM load. Patients' activation was generally less responsive to load changes than control subjects', and different patterns of between-group differences were observed for memory encoding and retrieval. In the specific case of successful retrieval, patients recruited additional neural circuits unused by control subjects. Behavioral effects were generally consistent with these imaging results.
Differential findings of overactivation and underactivation may be attributable to patients' decreased ability to focus and allocate neural resources at task-appropriate levels. Additionally, differences between encoding and retrieval suggest that WM dysfunction may be manifested differently during the distinct phases of encoding, maintenance, and retrieval.
先前针对精神分裂症工作记忆（WM）的神经影像学研究通常聚焦于背外侧前额叶皮层，结果相互矛盾，这可能是由于任务和分析技术的选择各异。我们在几种工作记忆负荷水平下研究神经功能变化，以更全面地了解精神分裂症中工作记忆功能障碍的情况。
我们使用了一种版本的斯特恩伯格项目识别范式，在五种不同负荷水平下测试工作记忆功能。18名精神分裂症患者和18名匹配的健康对照者接受了3特斯拉的功能磁共振成像扫描。
根据工作记忆负荷的不同，观察到患者存在过度激活和激活不足的模式。患者的激活对负荷变化的反应通常不如对照对象，并且在记忆编码和检索方面观察到组间差异的不同模式。在成功检索的特定情况下，患者动用了对照对象未使用的额外神经回路。行为效应总体上与这些影像学结果一致。
过度激活和激活不足的差异结果可能归因于患者在任务适当水平上集中和分配神经资源的能力下降。此外，编码和检索之间的差异表明，工作记忆功能障碍在编码、维持和检索的不同阶段可能表现不同。
