Leibniz-Research Centre for Working Environment and Human Factors, TU, Dortmund, Germany.
Leibniz-Research Centre for Working Environment and Human Factors, TU, Dortmund, Germany.
Neuroimage. 2017 Nov 15;162:73-85. doi: 10.1016/j.neuroimage.2017.08.057. Epub 2017 Aug 26.
Attention can be allocated toward mental representations in working memory also after the initial encoding of information has been completed. It was shown that focusing on only one item within working memory transfers this representation into a protected state, reducing its susceptibility to interference by incoming signals. The present study investigated the nature of this retroactive cue (retro-cue) benefit by means of oscillatory activity in the EEG. In a working memory task with a retro-cue indicating one, two or three memory representations as relevant and a block-wise distractor display presented after the retro-cue, participants had to remember the orientation of a colored bar. On behavioral level, we found that the interfering effect of the distractor display on memory performance could be prevented when a retro-cue reduced the number of attended representations in working memory. However, only the one-item retro-cue led to an overall increase in task performance compared to a condition without a retro-cue. The neural basis of this special representational status was investigated by means of oscillatory parameters in the EEG and a clustering approach on level of the independent components (ICs) in the signal. The retroactive reduction of attended working memory representations was reflected in a suppression of alpha power over right parietal and parieto-occipital sites. In addition, we found that an IC cluster representing oscillatory activity in the mu/beta range (10-12 Hz and 20-24 Hz) with a source in sensorimotor cortex revealed a power suppression already prior to the memory probe following the one-item retro-cue. This suggests that the retro-cue benefit results in large parts from the possibility to focus attention on one particular item in working memory and initiate motor planning processes already ahead of the probe stimulus indicating the respective response.
注意力也可以在信息的初始编码完成后分配到工作记忆中的心理表象上。研究表明，专注于工作记忆中的一个项目会将该表象转移到受保护的状态，从而降低其受到传入信号干扰的敏感性。本研究通过 EEG 中的振荡活动来研究这种回溯提示（回溯提示）的好处的性质。在一项带有回溯提示的工作记忆任务中，回溯提示指示一个、两个或三个记忆表象为相关，并且在回溯提示后呈现块式干扰显示，参与者必须记住彩色条的方向。在行为水平上，我们发现，当回溯提示减少工作记忆中被注意的表象数量时，可以防止干扰显示对记忆表现的干扰效应。然而，只有一个项目的回溯提示与没有回溯提示的条件相比，会导致任务表现的整体提高。通过 EEG 中的振荡参数和信号水平上的独立成分（ICs）聚类方法，研究了这种特殊表示状态的神经基础。回溯提示减少被注意的工作记忆表象反映在右顶叶和顶枕叶区域的 alpha 功率抑制上。此外，我们发现，一个代表感觉运动皮层中振荡活动的 IC 集群（10-12 Hz 和 20-24 Hz）在一个项目的回溯提示后，在记忆探针之前就已经显示出功率抑制。这表明回溯提示的好处主要来自于将注意力集中在工作记忆中的一个特定项目上的可能性，并在指示相应反应的探针刺激之前，启动运动计划过程。
