Bernstein Center for Computational Neuroscience and Berlin Center for Advanced Neuroimaging and Clinic for Neurology, Charité Universitätsmedizin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin 10115, Germany.
Department of Psychology, City, University of London, London EC1V 0HB, United Kingdom.
Neuroimage. 2021 Feb 1;226:117595. doi: 10.1016/j.neuroimage.2020.117595. Epub 2020 Nov 26.
Representations of sensory working memory can be found across the entire neocortex. But how are verbal working memory (VWM) contents retained in the human brain? Here we used fMRI and multi-voxel pattern analyses to study Chinese native speakers (15 males, 13 females) memorizing Chinese characters. Chinese characters are uniquely suitable to study VWM because verbal encoding is encouraged by their complex visual appearance and monosyllabic pronunciation. We found that activity patterns in Broca's area and left premotor cortex carried information about the memorized characters. These language-related areas carried (1) significantly more information about cued characters than those not cued for memorization, (2) significantly more information on the left than the right hemisphere and (3) significantly more information about Chinese symbols than complex visual patterns which are hard to verbalize. In contrast, early visual cortex carries a comparable amount of information about cued and uncued stimuli and is thus unlikely to be involved in memory retention. This study provides evidence for verbal working memory maintenance in a distributed network of language-related brain regions, consistent with distributed accounts of WM. The results also suggest that Broca's area and left premotor cortex form the articulatory network which serves articulatory rehearsal in the retention of verbal working memory contents.
感觉工作记忆的表现可以在整个新皮质中找到。但是，人类大脑如何保留言语工作记忆（VWM）的内容？在这里，我们使用 fMRI 和多体素模式分析来研究母语为汉语的人（男性 15 名，女性 13 名）记忆汉字。汉字非常适合研究 VWM，因为它们复杂的视觉外观和单音节发音鼓励了言语编码。我们发现，布罗卡区和左前运动皮层的活动模式携带了关于记忆字符的信息。这些与语言相关的区域携带的信息为：（1）提示字符的信息量明显多于未提示记忆的字符；（2）左半球的信息量明显多于右半球；（3）汉字符号的信息量明显多于难以言语化的复杂视觉模式。相比之下，早期视觉皮层携带关于提示和未提示刺激的信息量相当，因此不太可能参与记忆保留。这项研究为言语工作记忆在与语言相关的大脑区域的分布式网络中的维持提供了证据，与 WM 的分布式描述一致。结果还表明，布罗卡区和左前运动皮层形成了发音网络，该网络在言语工作记忆内容的保留中进行发音复述。
