Dissociating the effects of Sternberg working memory demands in prefrontal cortex
Dissociating the effects of Sternberg working memory demands in prefrontal cortex
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DOI：
10.1016/j.pscychresns.2006.08.002
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发表时间：
2007-02-28
影响因子：
2.3
通讯作者：
Goldberg, Terry E.
中科院分区：
文献类型：
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作者：
Altamura, Mario;Elvevag, Brita;Goldberg, Terry E.
早期对工作记忆(WM)的神经成像研究表明，随着维持和负荷需求的增加，背外侧前额叶皮质(DLPFC)的活动增加。然而，很少有研究在行为和生理水平上仔细地消除这两个工作记忆过程的歧义。目前的功能磁共振成像(FMRI)研究的目的是在前额叶皮质内定位选择性负荷敏感、延迟敏感或两者兼而有之的部位。我们对18名右撇子正常受试者进行了3特斯拉下的功能磁共振成像研究，采用的是Sternberg任务的区块设计。通过改变内存集大小(3、5或8个字母)来处理WM负载。采用字母组刺激和探测刺激之间的两个时延(S和S)来考察记忆维持的效果。在负荷操作中，DLPFC被强烈激活，而作为延迟函数的激活仅限于左侧运动前区和Broca区。此外，右侧的前额叶皮质区域(BA 46)被发现仅受负荷的影响。这些结果表明，在编码和/或决策过程中，自上而下调节注意力或认知控制的可能性可能是由这些区域调节的。爱思唯尔爱尔兰有限公司出版。
Earlier neuroimaging studies of working memory (WM) have demonstrated that dorsolateral prefrontal cortex (DLPFC) activity increases as maintenance and load demand increases. However, few studies have carefully disambiguated these two WM processes at the behavioral and physiological levels. The objective of the present functional resonance imaging (fMRI) study was to map within prefrontal cortex locales that are selectively load sensitive, delay sensitive, or both. We studied 18 right-handed normal subjects with fMRI at 3 Tesla during a block design version of the Sternberg task. WM load was manipulated by varying the memory set size (3, 5, or 8 letters). The effect of memory maintenance was examined by employing two time delays (I s and 6 s) between the letter set and probe stimuli. The DLPFC was strongly activated in load manipulation, whereas activation as a function of delay was restricted to the left premotor regions and Broca's areas. Moreover, regions of prefrontal cortex on the right (BA 46) were found to be exclusively affected by load. These results suggest the possibility that top-down modulation of attention or cognitive control at encoding and/or decisionmaking may be mediated by these areas. Published by Elsevier Ireland Ltd.