Sliwinska Magdalena W, Violante Inês R, Wise Richard J S, Leech Robert, Devlin Joseph T, Geranmayeh Fatemeh, Hampshire Adam
Department of Medicine, Imperial College London, London, W12 0NN, United Kingdom, and
Department of Medicine, Imperial College London, London, W12 0NN, United Kingdom, and.
J Neurosci. 2017 Aug 9;37(32):7606-7618. doi: 10.1523/JNEUROSCI.3857-16.2017. Epub 2017 Jul 4.
It is well established that networks within multiple-demand cortex (MDC) become active when diverse skills and behaviors are being learnt. However, their causal role in learning remains to be established. In the present study, we first performed functional magnetic resonance imaging on healthy female and male human participants to confirm that MDC was most active in the initial stages of learning a novel vocabulary, consisting of pronounceable nonwords (pseudowords), each associated with a picture of a real object. We then examined, in healthy female and male human participants, whether repetitive transcranial magnetic stimulation of a frontal midline node of the cingulo-opercular MDC affected learning rates specifically during the initial stages of learning. We report that stimulation of this node, but not a control brain region, substantially improved both accuracy and response times during the earliest stage of learning pseudoword-object associations. This stimulation had no effect on the processing of established vocabulary, tested by the accuracy and response times when participants decided whether a real word was accurately paired with a picture of an object. These results provide evidence that noninvasive stimulation to MDC nodes can enhance learning rates, thereby demonstrating their causal role in the learning process. We propose that this causal role makes MDC candidate target for experimental therapeutics; for example, in stroke patients with aphasia attempting to reacquire a vocabulary. Learning a task involves the brain system within which that specific task becomes established. Therefore, successfully learning a new vocabulary establishes the novel words in the language system. However, there is evidence that in the early stages of learning, networks within multiple-demand cortex (MDC), which control higher cognitive functions, such as working memory, attention, and monitoring of performance, become active. This activity declines once the task is learnt. The present study demonstrated that a node within MDC, located in midline frontal cortex, becomes active during the early stage of learning a novel vocabulary. Importantly, noninvasive brain stimulation of this node improved performance during this stage of learning. This observation demonstrated that MDC activity is important for learning.
众所周知，当人们学习各种技能和行为时，多需求皮层（MDC）中的神经网络会变得活跃。然而，它们在学习中的因果作用仍有待确定。在本研究中，我们首先对健康的女性和男性人类参与者进行了功能磁共振成像，以确认MDC在学习由可发音的非单词（假词）组成的新词汇的初始阶段最为活跃，每个假词都与一个真实物体的图片相关联。然后，我们在健康的女性和男性人类参与者中研究了扣带回-脑岛MDC的额中线节点的重复经颅磁刺激是否在学习的初始阶段特别影响学习速度。我们报告说，刺激这个节点，而不是对照脑区，在学习假词-物体关联的最早阶段显著提高了准确性和反应时间。这种刺激对已建立词汇的处理没有影响，通过参与者判断一个真实单词是否与一个物体的图片准确配对时的准确性和反应时间来测试。这些结果提供了证据，表明对MDC节点的非侵入性刺激可以提高学习速度，从而证明它们在学习过程中的因果作用。我们提出，这种因果作用使MDC成为实验性治疗的候选靶点；例如，对于试图重新学习词汇的失语症中风患者。学习一项任务涉及该特定任务得以确立的大脑系统。因此，成功学习一个新词汇会在语言系统中确立这些新单词。然而，有证据表明，在学习的早期阶段，控制更高认知功能（如工作记忆、注意力和表现监测）的多需求皮层（MDC）中的神经网络会变得活跃。一旦任务学会，这种活动就会下降。本研究表明，位于额中线皮层的MDC中的一个节点在学习新词汇的早期阶段会变得活跃。重要的是，对这个节点的非侵入性脑刺激在这个学习阶段提高了表现。这一观察结果表明MDC活动对学习很重要。
