Distractor-resistant Short-Term Memory Is Supported by Transient Changes in Neural Stimulus Representations
Distractor-resistant Short-Term Memory Is Supported by Transient Changes in Neural Stimulus Representations
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DOI：
10.1162/jocn_a_01141
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发表时间：
2017-09-01
影响因子：
3.2
通讯作者：
Fiebach, Christian J.
中科院分区：
文献类型：
--
作者：
Derrfuss, Jan;Ekman, Matthias;Fiebach, Christian J.
在一个复杂的世界中，目标导向的行为需要保持与目标相关的信息，尽管有多种分心来源。然而，抵抗分心的工作或短期记忆(STM)背后的大脑机制还不完全清楚。尽管猴子的早期单一单位记录和人类的fMRI研究表明，大脑前额叶外侧皮质也参与其中，但最近的研究强调，在注意力分散的情况下，后脑皮质对于主动维持视觉信息也很重要。在这里，我们使用延迟的样本匹配任务和fMRI数据的多变量探照灯分析来研究STM在三个延长的延迟阶段的维护。参与者在未填充的前分心延迟、分心填充的延迟和未填充的分心后延迟中保持两个样本(面孔或房屋)。在枕区、颞区和顶后区的所有三个延迟期，STM内容(面部和房屋)都可以高于机会地被解码。被训练来区分面孔和房屋维护的分类器成功地从分心前到分心后延迟以及反之亦然，但没有概括到分心延迟时间段。此外，分类器在所有延迟阶段的表现与室内试验中的行为表现相关，但与面对面试验中的行为表现无关。我们的结果表明，在牵张过程中和牵张后，分布的后部皮质，而不是外侧前额叶，参与了主动维持。他们还表明，在干扰物存在的情况下，支持STM维持的神经编码会短暂改变，并在分散注意力后恢复。与行为的相关性表明，积极的STM维持在室内试验中尤其相关，而面孔试验可能更依赖于长期记忆的贡献。
Goal-directed behavior in a complex world requires the maintenance of goal-relevant information despite multiple sources of distraction. However, the brain mechanisms underlying distractor-resistant working or short-term memory (STM) are not fully understood. Although early single-unit recordings in monkeys and fMRI studies in humans pointed to an involvement of lateral prefrontal cortices, more recent studies highlighted the importance of posterior cortices for the active maintenance of visual information also in the presence of distraction. Here, we used a delayed match-to-sample task and multivariate searchlight analyses of fMRI data to investigate STM maintenance across three extended delay phases. Participants maintained two samples (either faces or houses) across an unfilled pre-distractor delay, a distractor-filled delay, and an unfilled post-distractor delay. STM contents (faces vs. houses) could be decoded above-chance in all three delay phases from occipital, temporal, and posterior parietal areas. Classifiers trained to distinguish face versus house maintenance successfully generalized from pre- to post-distractor delays and vice versa, but not to the distractor delay period. Furthermore, classifier performance in all delay phases was correlated with behavioral performance in house, but not face, trials. Our results demonstrate the involvement of distributed posterior, but not lateral prefrontal, cortices in active maintenance during and after distraction. They also show that the neural code underlying STM maintenance is transiently changed in the presence of distractors and reinstated after distraction. The correlation with behavior suggests that active STM maintenance is particularly relevant in house trials, whereas face trials might rely more strongly on contributions from long-term memory.