Abstract：
The role hemispheric lateralization in the prefrontal cortex plays for episodic memory formation in general, and for emotionally valenced information in particular, is debated. In a randomized, double-blind, and sham-controlled design, healthy young participants (n = 254) performed 2 runs of encoding to categorize the perceptual, semantic, or emotionally valenced (positive or negative) features of words followed by a free recall and a recognition task. To resolve competing hypotheses about the contribution of each hemisphere, we modulated left or right dorsolateral prefrontal cortex (DLPFC) activity using transcranial direct current stimulation during encoding (1 mA, 20 min). With stimulation of the left DLPFC, but not the right DLPFC, encoding and free recall performance improved particularly for words that were processed semantically. In addition, enhancing left DLPFC activity increased memory formation for positive content while reducing that for negative content. In contrast, promoting right DLPFC activity increased memory formation for negative content. The left DLPFC assesses semantic properties of new memory content at encoding and thus influences how successful new episodic memories are established. Hemispheric laterlization-more active left DLPFC and less active right DLPFC-at the encoding stage shifts the formation of memory traces in favor of positively valenced content.
摘要：
大脑半球偏侧化在前额叶皮层中的作用通常是形成情景记忆，特别是对于情感上有价值的信息，正在辩论。在一个随机的，双盲,和假控制设计，健康的年轻参与者(n=254)进行了2次编码来对感知进行分类，语义，或情感上有价（积极或消极）的单词特征，然后是自由回忆和识别任务。为了解决关于每个半球贡献的相互竞争的假设，我们在编码过程中使用经颅直流电刺激（1mA，20分钟）。在左侧DLPFC的刺激下，但不是正确的DLPFC，编码和自由召回性能得到了改善，特别是对于语义处理的单词。此外,增强左侧DLPFC活性可增加阳性内容的记忆形成，而降低阴性内容的记忆形成。相比之下,促进正确的DLPFC活动增加了负面内容的记忆形成。左边的DLPFC在编码时评估新记忆内容的语义属性，从而影响如何成功建立新的情景记忆。在编码阶段，半球侧向化-更活跃的左侧DLPFC和更不活跃的右侧DLPFC-改变了记忆痕迹的形成，有利于积极的含量。
