Division of Neuropsychiatry, Department of Brain and Neuroscience, Tottori University Faculty of Medicine, 36-1 Nishi-cho, Yonago, Tottori 683-8504, Japan.
Neurosci Res. 2011 May;70(1):91-7. doi: 10.1016/j.neures.2011.01.001. Epub 2011 Jan 15.
Many neuropsychological studies demonstrate impairment of working memory in patients with major depressive disorder (MDD). However, there are not enough functional neuroimaging studies of MDD patients seeking for the underlying brain activity relevant to working memory function. The objective of this study is to evaluate prefrontal hemodynamic response related to working memory function in patients with MDD. Twenty-four subjects with MDD and 26 age- and gender-matched healthy subjects were recruited for the present study. We measured hemoglobin concentration changes in the prefrontal and superior temporal cortical surface areas during the execution of working memory task (WM; 2-back, letter version) using 52-channel near-infrared spectroscopy (NIRS), which enables real-time monitoring of task-related changes in cerebral blood volumes in the cortical surface areas. MDD patients showed a smaller increase in lateral prefrontal and superior temporal cortex activation during the 2-back task and associated poorer task performance than healthy controls. The results coincided with previous findings in terms of working memory deficits and prefrontal cortex dysfunction in MDD patients, but contradicted with some previous fMRI studies that suggested increased cortical activity during the working memory task in patients with depression. The contradiction may, in part, be explained by a relatively low level of cognitive demand imposed on the subjects in the present study.
许多神经心理学研究表明，重度抑郁症（MDD）患者的工作记忆受损。然而，针对寻求与工作记忆功能相关的潜在大脑活动的 MDD 患者的功能性神经影像学研究还不够充分。本研究的目的是评估 MDD 患者的工作记忆功能相关的前额叶血液动力学反应。本研究共招募了 24 名 MDD 患者和 26 名年龄和性别匹配的健康对照者。我们使用 52 通道近红外光谱（NIRS）测量了执行工作记忆任务（WM；2 回，字母版）时前额叶和颞上皮质表面区域的血红蛋白浓度变化，这使得能够实时监测皮质表面区域的与任务相关的脑血流变化。与健康对照组相比，MDD 患者在执行 2 回任务时，外侧前额叶和颞上皮质的激活增加较少，并且与较差的任务表现相关。这些结果与 MDD 患者工作记忆缺陷和前额叶皮层功能障碍的先前发现一致，但与一些先前的 fMRI 研究相矛盾，这些研究表明抑郁症患者在工作记忆任务期间皮质活动增加。这种矛盾可能部分可以通过本研究中对受试者施加的相对较低的认知需求来解释。
