Department of Neurology, Division of Cognitive Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
Department of Biological Psychology, Institute of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany.
Brain Struct Funct. 2019 Jan;224(1):485-499. doi: 10.1007/s00429-018-1784-0. Epub 2018 Nov 2.
Verbal working memory is one of the most studied non-motor functions with robust cerebellar involvement. While the superior cerebellum (lobule VI) has been associated with articulatory control, the inferior cerebellum (lobule VIIIa) has been linked to phonological storage. The present study was aimed to elucidate the differential roles of these regions by investigating whether the cerebellum might contribute to verbal working memory via predictions based on sequence learning/detection. 19 healthy adult subjects completed an fMRI-based Sternberg task which included repeating and novel letter sequences that were phonologically similar or dissimilar. It was hypothesized that learning a repeating sequence of study letters would reduce phonological storage demand and associated right inferior cerebellar activations and that this effect would be modulated by phonological similarity of the study letters. Specifically, while increased phonological storage demand due to high phonological similarity was expected to be reflected in increased right inferior cerebellar activations for similar relative to dissimilar study letters, the reduction in activation for repeating relative to novel sequences was expected to be more profound for phonologically similar than for dissimilar study letters, especially at higher memory load. Results confirmed the typical effects of cognitive load (5 vs. 2 study letters) and phonological similarity in several cerebellar and neocortical brain regions as well as in behavioral data (accuracy and response time). Importantly, activations in superior and inferior cerebellar regions were differentially modulated as a function of similarity and sequence novelty, indicating that particularly lobule VIIIa may contribute to verbal working memory by generating predictions of letter sequences that reduce the likelihood of phonological loop failure before stored items need to be retrieved. The present study is consistent with other investigations that support prediction, which can be based on sequence learning or detection, as an overarching cerebellar function.
言语工作记忆是研究最多的非运动功能之一，与小脑有很强的关联。虽然上小脑（VI 小叶）与发音控制有关，但下小脑（VIIIa 小叶）与语音存储有关。本研究旨在通过基于序列学习/检测的预测来阐明这些区域的差异作用，以探讨小脑是否可以通过预测来促进言语工作记忆。19 名健康成年受试者完成了一项基于 fMRI 的 Sternberg 任务，该任务包括重复和新的字母序列，这些序列在语音上相似或不同。假设学习重复的学习字母序列将减少语音存储需求和相关的右小脑下叶激活，并且这种效应将受到学习字母的语音相似性的调节。具体来说，由于高语音相似性而增加的语音存储需求预计会反映在相似学习字母相对于不相似学习字母的右小脑下叶激活增加上，而重复序列相对于新序列的激活减少预计在语音相似的情况下比在不相似的学习字母情况下更为明显，尤其是在较高的记忆负荷下。结果证实了认知负荷（5 个与 2 个学习字母）和语音相似性的典型影响，这些影响在几个小脑和新皮质脑区以及行为数据（准确性和反应时间）中都得到了体现。重要的是，小脑上叶和下叶的激活受到相似性和序列新颖性的差异调节，这表明特别是 VIIIa 小叶可能通过生成减少存储项目需要检索之前语音环路失败可能性的字母序列预测来促进言语工作记忆。本研究与其他支持预测的研究一致，预测可以基于序列学习或检测，作为小脑的一个总体功能。
