Department of Psychology,
Center for Complex Systems and Brain Sciences, and.
J Neurosci. 2018 Oct 3;38(40):8538-8548. doi: 10.1523/JNEUROSCI.1566-18.2018. Epub 2018 Aug 20.
Working memory (WM) enables the flexible representation of information over short intervals. It is well established that WM performance can be enhanced by a retrospective cue presented during storage, yet the neural mechanisms responsible for this benefit are unclear. Here, we tested several explanations for retrospective cue benefits by quantifying changes in spatial WM representations reconstructed from alpha-band (8-12 Hz) EEG activity recorded from human participants (both sexes) before and after the presentation of a retrospective cue. This allowed us to track cue-related changes in WM representations with high temporal resolution (tens of milliseconds). Participants encoded the locations of two colored discs for subsequent report. During neutral trials, an uninformative cue instructed participants to remember the locations of both discs across a blank delay, and we observed a monotonic decrease in the fidelity of reconstructed spatial WM representations with time. During valid trials, a 100% reliable cue indicated that the color of the disc participants would be probed to report. Critically, valid cues were presented immediately after the termination of the encoding display ["valid early" (VE) trials] or midway through the delay period ["valid late" (VL) trials]. During VE trials, the gradual loss of location-specific information observed during neutral trials was eliminated, while during VL trials it was partially reversed. Our findings suggest that retrospective cues engage several different mechanisms that together serve to mitigate information loss during WM storage. Working memory (WM) performance can be improved by a cue presented during storage. This effect, termed a retrospective cue benefit, has been used to explore the limitations of attentional prioritization in WM. However, the mechanisms responsible for retrospective cue benefits are unclear. Here we tested several explanations for retrospective cue benefits by examining how they influence WM representations reconstructed from human EEG activity. This approach allowed us to visualize, quantify, and track the effects of retrospective cues with high temporal resolution (on the order of tens of milliseconds). We show that under different circumstances retrospective cues can both eliminate and even partially reverse information loss during WM storage, suggesting that retrospective cue benefits have manifold origins.
工作记忆 (WM) 使信息能够在短时间内灵活表示。已经证实，在存储过程中呈现回溯提示可以增强 WM 性能，但负责这种益处的神经机制尚不清楚。在这里，我们通过量化从人类参与者 (男女皆有) 在呈现回溯提示前后记录的 alpha 波段 (8-12 Hz) EEG 活动中重建的空间 WM 表示的变化，来测试回溯提示益处的几种解释。这使我们能够以高时间分辨率 (几十毫秒) 跟踪与提示相关的 WM 表示变化。参与者为随后的报告编码两个彩色圆盘的位置。在中性试验中，一个无信息提示指示参与者在空白延迟期间记住两个圆盘的位置，我们观察到重建的空间 WM 表示的保真度随着时间的推移呈单调下降。在有效试验中，100%可靠的提示指示参与者要报告的圆盘颜色。关键的是，有效提示在编码显示结束后立即呈现(“有效早期”(VE) 试验)或在延迟期间中途呈现(“有效晚期”(VL) 试验)。在 VE 试验中，消除了在中性试验中观察到的位置特异性信息的逐渐丧失，而在 VL 试验中，部分得到了逆转。我们的发现表明，回溯提示利用了几种不同的机制，这些机制共同有助于减轻 WM 存储过程中的信息损失。工作记忆 (WM) 性能可以通过存储过程中呈现的提示来提高。这种效果称为回溯提示益处，已被用于探索 WM 中注意力优先化的局限性。然而，负责回溯提示益处的机制尚不清楚。在这里，我们通过检查它们如何影响从人类 EEG 活动重建的 WM 表示，来测试回溯提示益处的几种解释。这种方法使我们能够以高时间分辨率(几十毫秒)可视化、量化和跟踪回溯提示的影响。我们表明，在不同情况下，回溯提示既可以消除，甚至部分逆转 WM 存储过程中的信息损失，这表明回溯提示益处具有多种来源。
