Abstract：
One critical approach for promoting the efficiency of memory is to adopt selective encoding strategies to prioritize more valuable information. Past neuroimaging studies have shown that value-directed modulation of verbal memory depends heavily on the engagement of left-lateralized semantic processing regions, particularly in the ventrolateral prefrontal cortex (VLPFC). In the present study, we used high-definition transcranial direct current stimulation (HD-tDCS) to seek evidence for a causal role of left VLPFC in supporting the memory advantage for high-value items. Three groups of healthy young adult participants were presented with lists of words to remember, with each word accompanied by an arbitrarily assigned point value. During the first session, all participants received sham stimulation as they encoded five lists of 30 words each. Two of these lists were immediately tested with free recall, with feedback given to allow participants to develop metacognitive insight and strategies to maximize their point total. The second session had the exact same structure as the first, but the groups differed in whether they received continued sham stimulation (N = 22) or anodal stimulation of the left VLPFC (N = 21) or right VLPFC (N = 20). Those lists not tested with immediate recall were tested with recognition judgments after a one-day delay. Since no brain stimulation was applied during this Day 2 test, any performance differences can be attributed to the effects of stimulation on Day 1 encoding processes. Anodal stimulation of left VLPFC significantly boosted participants\' memory encoding selectivity. In comparison, no such effect was seen in participants who received right VLPFC or sham stimulation. Estimates of recollection- and familiarity-based responding revealed that left VLPFC stimulation specifically amplified the effects of item value on recollection. These results demonstrate a causal role for left VLPFC in the implementation of selective value-directed encoding strategies, putatively by boosting deep semantic processing of high-value words. Our findings also provide further evidence on the hemispheric lateralization of value-directed verbal memory encoding.
摘要：
提高记忆效率的一个关键方法是采用选择性编码策略来优先考虑更有价值的信息。过去的神经影像学研究表明，言语记忆的价值导向调制在很大程度上取决于左侧语义处理区域的参与，特别是在腹外侧前额叶皮质（VLPFC）。在本研究中,我们使用高清直流电刺激(HD-tDCS)来寻找左VLPFC在支持高价值项目记忆优势方面的因果作用的证据.向三组健康的年轻成年人参与者展示了要记住的单词列表，每个单词都带有任意分配的点值。在第一届会议期间，所有参与者都接受了假刺激,因为他们编码了5个列表,每个列表30个单词.其中两份名单立即进行了免费召回测试，提供反馈，让参与者发展元认知洞察力和策略，以最大限度地提高他们的总积分。第二届会议的结构与第一届会议完全相同，但两组在是否接受左侧VLPFC(N=21)或右侧VLPFC(N=20)的持续假刺激(N=22)或阳极刺激方面存在差异.那些未经立即召回测试的列表在延迟一天后进行了识别判断测试。由于在第2天测试中没有施加脑刺激，任何性能差异都可以归因于刺激对第1天编码过程的影响。左侧VLPFC的阳极刺激显着提高了参与者的记忆编码选择性。相比之下,在接受右VLPFC或假刺激的参与者中未观察到这种效应.基于回忆和熟悉度的响应估计显示，左VLPFC刺激特别放大了项目价值对回忆的影响。这些结果证明了左VLPFC在选择性价值导向编码策略的实施中的因果作用，通过促进高价值词的深度语义处理来推测。我们的发现还为价值导向的言语记忆编码的半球偏侧化提供了进一步的证据。
