Department of Psychology, University of California, Los Angeles, Los Angeles, CA, 90095, USA; Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104, USA; Department of Psychology, Tsinghua University, Beijing, 100084, China.
Department of Psychology, University of Chicago, Chicago, IL, 60637, USA.
Neuropsychologia. 2023 Mar 12;181:108489. doi: 10.1016/j.neuropsychologia.2023.108489. Epub 2023 Jan 18.
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.
一种提高记忆效率的关键方法是采用选择性编码策略，优先处理更有价值的信息。过去的神经影像学研究表明，价值导向的言语记忆调制在很大程度上依赖于左侧语义处理区域的参与，特别是在腹外侧前额叶皮层（VLPFC）。在本研究中，我们使用高清晰度经颅直流电刺激（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。三组健康年轻成年参与者被呈现要记住的单词列表，每个单词都伴随着任意分配的分数。在第一阶段，所有参与者在编码 5 个 30 个单词的列表时都接受了假刺激。其中两个列表立即进行自由回忆测试，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分。第二阶段与第一阶段完全相同，但组间差异在于他们是否继续接受假刺激（N=22）或左 VLPFC（N=21）或右 VLPFC（N=20）的阳极刺激。未进行即时回忆测试的列表在一天后进行识别判断测试。由于在第二天的测试中没有应用脑刺激，因此任何性能差异都可以归因于刺激对第一天编码过程的影响。左 VLPFC 的阳极刺激显著提高了参与者的记忆编码选择性。相比之下，接受右 VLPFC 或假刺激的参与者则没有这种效果。对回忆和熟悉度反应的估计表明，左 VLPFC 刺激特别放大了项目价值对回忆的影响。这些结果表明，左 VLPFC 在实施选择性价值导向编码策略中起因果作用，推测通过增强高价值单词的深层语义处理。我们的发现还为价值导向言语记忆编码的半球偏侧化提供了进一步的证据。
