Rehearsal of tactile working memory: Premotor cortex recruits two dissociable neuronal content representations,Human Brain Mapping

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Rehearsal of tactile working memory: Premotor cortex recruits two dissociable neuronal content representations
Human Brain Mapping ( IF 3.5 ) Pub Date : 2020-10-03 , DOI: 10.1002/hbm.25220
Timo Torsten Schmidt ₁ , Pia Schröder ₁ , Pablo Reinhardt ₁ , Felix Blankenburg ₁

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Recent working memory (WM) research has focused on identifying brain regions that retain different types of mental content. Only few neuroimaging studies have explored the mechanism of attention‐based refreshing, which is a type of rehearsal and is thought to implement the dynamic components of WM allowing for update of WM contents. Here, we took advantage of the distinct coding properties of the superior parietal lobe (SPL), which retains spatial layout information, and the right inferior frontal gyrus (IFG), which retains frequency information of vibrotactile stimuli during tactile WM. In an fMRI delayed match‐to‐sample task, participants had to internally rehearse sequences of spatial layouts or vibratory frequencies. Our results replicate the dissociation of SPL and IFG for the retention of layout and frequency information in terms of activation differences between conditions. Additionally, we found strong premotor cortex (PMC) activation during rehearsal of either stimulus type. To explore interactions between these regions we used dynamic causal modeling and found that activation within the network was best explained by a model that allows the PMC to drive activity in the SPL and IFG during rehearsal. This effect was content‐specific, meaning that the PMC showed stronger influence on the SPL during pattern rehearsal and stronger influence on the IFG during frequency rehearsal. In line with previously established PMC contributions to sequence processing, our results suggest that it acts as a content‐independent area that flexibly recruits content‐specific regions to bring a WM item into the focus of attention during the rehearsal of tactile stimulus sequences.

中文翻译：

触觉工作记忆的排练：前运动皮层招募两个可分离的神经元内容表征

最近的工作记忆（WM）研究重点是识别保留不同类型心理内容的大脑区域。只有少数神经影像学研究探索了基于注意力的刷新机制，这是一种排练，被认为实现了 WM 的动态组件，允许更新 WM 内容。在这里，我们利用了顶叶上叶（SPL）和右额下回（IFG）的独特编码特性，前者保留了空间布局信息，后者保留了触觉 WM 期间振动触觉刺激的频率信息。在功能磁共振成像延迟匹配样本任务中，参与者必须在内部排练空间布局或振动频率的序列。我们的结果复制了 SPL 和 IFG 的分离，以根据条件之间的激活差异保留布局和频率信息。此外，我们发现在任何一种刺激类型的排练过程中，前运动皮层（PMC）都会被强烈激活。为了探索这些区域之间的相互作用，我们使用动态因果模型，发现网络内的激活最好通过一个模型来解释，该模型允许 PMC 在排练期间驱动 SPL 和 IFG 中的活动。这种效果是特定于内容的，这意味着 PMC 在模式排练过程中对 SPL 表现出更强的影响，在频率排练过程中对 IFG 表现出更强的影响。与之前建立的 PMC 对序列处理的贡献一致，我们的结果表明，它充当内容独立区域，灵活地招募内容特定区域，以便在排练触觉刺激序列期间将 WM 项目引入注意焦点。

更新日期：2020-12-08

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