Institute for Brain and Behaviour, Vrije Universiteit Amsterdam, the Netherlands.
Department of General Practice & Elderly Care Medicine, Amsterdam Public Health Research Institute, Amsterdam University Medical Center, Location VUmc, Amsterdam, the Netherlands.
Cortex. 2021 Feb;135:61-77. doi: 10.1016/j.cortex.2020.11.011. Epub 2020 Dec 3.
To optimize task sequences, the brain must differentiate between current and prospective goals. We previously showed that currently and prospectively relevant object representations in working memory can be dissociated within object-selective cortex. Based on other recent studies indicating that a range of brain areas may be involved in distinguishing between currently relevant and prospectively relevant information in working memory, here we conducted multivoxel pattern analyses of fMRI activity in additional posterior areas (specifically early visual cortex and the intraparietal sulcus) as well as frontal areas (specifically the frontal eye fields and lateral prefrontal cortex). We assessed whether these areas represent the memory content, the current versus prospective status of the memory, or both. On each trial, participants memorized an object drawn from three different categories. The object was the target for either a first task (currently relevant), a second task (prospectively relevant), or for neither task (irrelevant). The results revealed a division of labor across brain regions: While posterior areas preferentially coded for content (i.e., the category), frontal areas carried information about the current versus prospective relevance status of the memory, irrespective of the category. Intraparietal sulcus revealed both strong category- and status-sensitivity, consistent with its hub function of combining stimulus and priority signals. Furthermore, cross-decoding analyses revealed that while current and prospective representations were similar prior to search, they became dissimilar during search, in posterior as well as frontal areas. The findings provide further evidence for a dissociation between content and control networks in working memory.
为了优化任务序列，大脑必须区分当前和预期目标。我们之前曾表明，工作记忆中当前和预期相关的目标表示可以在目标选择皮层内分离。基于其他最近的研究表明，一系列大脑区域可能参与区分工作记忆中当前相关和预期相关的信息，在这里，我们对额外的后区（特别是早期视觉皮层和顶内沟）以及前区（特别是额眼区和外侧前额叶皮层）的 fMRI 活动进行了多体素模式分析。我们评估了这些区域是否代表记忆内容、记忆的当前与预期状态，或者两者兼而有之。在每次试验中，参与者记忆三个不同类别中的一个对象。该对象是第一个任务（当前相关）、第二个任务（预期相关）或两个任务（不相关）的目标。结果显示，大脑区域之间存在分工：后区优先编码内容（即类别），而前区则携带关于记忆当前与预期相关性的信息，而与类别无关。顶内沟既表现出强烈的类别敏感性，又表现出强烈的状态敏感性，这与其作为结合刺激和优先级信号的枢纽功能一致。此外，交叉解码分析表明，当前和预期的表示在搜索之前是相似的，但在搜索过程中，无论是在后区还是在前区，它们都会变得不同。这些发现为工作记忆中内容和控制网络的分离提供了进一步的证据。
