Department of Psychology, Neuroscience and Behaviour, McMaster University, Ontario, Canada.
Brain Res. 2010 Aug 6;1347:90-103. doi: 10.1016/j.brainres.2010.05.085. Epub 2010 Jun 4.
Over the past decade, neuroimaging and electrophysiological studies of working memory (WM) have made progress in distinguishing the neural substrates of central executive (CE) functions from substrates of temporary storage subsystems. However, the degree to which CE-related processes and their substrates may be further fractionated is less clear. The present study measured event-related potentials (ERPs) in a running memory paradigm, to study modality-specific CE-related processes in verbal and spatial WM. Participants were asked to remember either verbal (digit identity) or spatial (digit location) information for the first or last three items in a variable length sequence of spatially distributed digit stimuli. Modality-specific WM demand-sensitive ERP amplitude effects were selectively observed over left prefrontal areas under verbal WM performance and over right prefrontal areas under spatial WM performance. In addition, distinct patterns of item-by-item sensitivity under high-CE-demand conditions suggested qualitatively different processing strategies for verbal versus spatial tasks. These results suggest that both modality-specific and task-general CE-related processes are likely operational in many WM situations and that careful dissociative methods will be needed to properly further fractionate and characterize these component CE-related processes and their neurological substrates.
在过去的十年中，工作记忆（WM）的神经影像学和电生理学研究在区分中央执行（CE）功能的神经基质与临时存储子系统的基质方面取得了进展。然而，CE 相关过程及其基质可能进一步细分的程度尚不清楚。本研究在连续记忆范式中测量了事件相关电位（ERPs），以研究言语和空间 WM 中与模态特异性 CE 相关的过程。要求参与者记住在空间分布的数字刺激的可变长度序列中的前三个或最后三个项目中的言语（数字身份）或空间（数字位置）信息。在言语 WM 表现下，仅在左前额区域观察到与模态特异性 WM 需求敏感的 ERP 幅度效应，而在空间 WM 表现下，仅在右前额区域观察到与模态特异性 WM 需求敏感的 ERP 幅度效应。此外，在高 CE 需求条件下的逐个项目的敏感性的不同模式表明，言语任务与空间任务的处理策略本质上不同。这些结果表明，在许多 WM 情况下，可能会涉及特定模态和任务一般的 CE 相关过程，并且需要仔细的分离方法来适当进一步细分和描述这些组件的 CE 相关过程及其神经基础。
