Kandemir Güven, Wolff Michael J, Karabay Aytaç, Stokes Mark G, Axmacher Nikolai, Akyürek Elkan G
Department of Experimental Psychology, University of Groningen, Groningen, The Netherlands.
Department of Experimental and Applied Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
Imaging Neurosci (Camb). 2024 May 20;2. doi: 10.1162/imag_a_00173. eCollection 2024.
In the dynamic environment we live in, the already limited information that human working memory can maintain needs to be constantly updated to optimally guide behaviour. Indeed, previous studies showed that leading up to a response, representations maintained in working memory representations are transformed continuously. This goes hand-in-hand with the removal of task-irrelevant items. However, does such removal also include the representations of stimuli as they were originally, prior to transformation? Here, we assessed the neural representation of task-relevant transformed representations, and the no-longer-relevant veridical representations they originated from. We applied multivariate pattern analysis to electroencephalographic data during maintenance of orientation gratings with and without mental rotation. During maintenance, we perturbed the representational network by means of a visual impulse stimulus, and were thus able to successfully decode veridical as well as imaginary, transformed orientation gratings from impulse-driven activity. The impulse response reflected only task-relevant (cued), but not task-irrelevant (uncued) items, suggesting that the latter were quickly discarded from working memory. By contrast, even though the original cued orientation gratings were also no longer task-relevant after mental rotation, these items continued to be represented next to the rotated ones, in different representational formats. This seemingly inefficient use of scarce working memory capacity was associated with reduced probe response times and may thus serve to increase precision and flexibility in guiding behaviour in dynamic environments.
在我们生活的动态环境中，人类工作记忆能够维持的本就有限的信息需要不断更新，以最优地指导行为。事实上，先前的研究表明，在做出反应之前，工作记忆中维持的表征会持续转变。这与去除任务无关项是同时进行的。然而，这种去除是否也包括刺激最初未经转变时的表征呢？在这里，我们评估了任务相关转变表征以及它们所源自的不再相关的真实表征的神经表征。我们在有和没有心理旋转的情况下，对定向光栅维持期间的脑电图数据应用了多变量模式分析。在维持期间，我们通过视觉脉冲刺激干扰表征网络，从而能够从脉冲驱动的活动中成功解码真实的以及想象中的、转变后的定向光栅。脉冲反应仅反映任务相关（被提示的）项目，而不反映任务无关（未被提示的）项目，这表明后者被迅速从工作记忆中丢弃。相比之下，尽管在心理旋转后最初被提示的定向光栅也不再与任务相关，但这些项目继续与旋转后的项目一起以不同的表征形式被表征。这种对稀缺工作记忆容量看似低效的利用与缩短的探测反应时间相关，因此可能有助于提高在动态环境中指导行为的精度和灵活性。
