Physiological characteristics of capacity constraints in working memory as revealed by functional MRI
Physiological characteristics of capacity constraints in working memory as revealed by functional MRI
复制标题
DOI：
10.1093/cercor/9.1.20
复制
发表时间：
1999-01-01
期刊：
影响因子：
3.7
通讯作者：
Weinberger, DR
中科院分区：
文献类型：
--
作者：
Callicott, JH;Mattay, VS;Weinberger, DR
工作记忆的一个基本特征是它处理信息的能力是有限的。虽然有许多关于工作记忆的脑图研究，但其容量限制的生理基础尚未得到解释。我们使用功能磁共振成像（fMRI）识别健康受试者的软木塞记忆容量特征。工作记忆容量的研究采用参数化的“n-back”工作记忆任务，该任务涉及认知负荷的增加和任务表现的最终降低。背外侧前额叶皮层（DLPFC）内的基因座仅表现出从最低到最高的“倒u”型神经生理反应，与能力受限反应一致。相比之下，DLPFC以外的区域在响应上更加异质性，并且经常表现出早期平台或持续增加的响应，这并没有反映出容量限制。然而，包括运动前皮层、丘脑和顶叶上小叶在内的零星位点也表现出假定的容量限制反应，这可能是DLPFC限制的上游效应，也可能是更广泛的网络容量限制的一部分。这些结果表明，工作记忆网络中的区域特定节点在生理领域受到容量限制，为当前工作记忆容量特征的探索提供了缺失的一环。
A fundamental characteristic of working memory is that its capacity to handle information is limited. While there have been many brain mapping studies of working memory, the physiological basis of its capacity limitation has not been explained. We identified characteristics of Corking memory capacity using functional magnetic resonance imaging (fMRI) in healthy subjects. Working memory capacity was studied using a parametric 'n-back' working memory task involving increasing cognitive load and ultimately decreasing task performance. Loci within dorsolateral prefrontal cortex (DLPFC) evinced exclusively an 'inverted-U' shaped neurophysiological response from lowest to highest toad, consistent with a capacity-constrained response. Regions outside of DLPFC, in contrast, were more heterogeneous in response and often showed early plateau or continuously increasing responses, which did not reflect capacity constraints. However, sporadic loci, including in the premotor cortex, thalamus and superior parietal lobule, also demonstrated putative capacity-constrained responses, perhaps arising as an upstream effect of DLPFC limitations or as part of a broader network-wide capacity limitation. These results demonstrate that regionally specific nodes within the working memory network are capacity-constrained in the physiological domain, providing a missing link in current explorations of the capacity characteristics of working memory.