工作记忆和长时记忆共享信息表征的ERP证据

Common Representations between Working Memory and Long-term Memory: Evidence from Event-Related Potentials

工作记忆和长时记忆共享记忆系统的信息表征网络,关系密切。实验采用事件相关电位技术记录长时记忆信息对工作记忆的长时语义启动和工作记忆对相关长时记忆信息的长时语义启动。结果显示:与新项目相比,学习项(即长时记忆信息)对工作记忆的目标信息产生了明显的行为启动效应,N2潜伏期、波幅和P3潜伏期也表现出明显的神经启动效应,即,学习项比新项目的反应时更短、N2和P3的潜伏期更短、N2更正,但学习对非记忆项的影响不大;工作记忆对相关的长时记忆信息也产生了神经启动,表现在类别比较任务中记忆类信息比其他信息(即,与工作记忆任务中的信息无关的内容)的N400更正。而且,这种神经启动也会因刺激重复次数的增多而降低:与新项目相比,学习项会使与之语义类似信息的N400更负。上述两种长时语义启动的存在及其ERPs的神经启动均为长时记忆和工作记忆使用共同信息表征的观点提供了证据支持。证据还表明,在工作记忆和长时记忆的相互作用中注意是关键的调节因素。

Human memory can be characterized as an elaborate network of stored representations. Researchers propose that both working memory （WM） and long-term memory （LTM） utilize same representations, and the representations they activate are in diverse patterns. So the similarity and coherence between WM and LTM are emphasized in the activation-based model, and the priming effect of LTM on WM and vice versa should be both found. By simultaneously recording event-related potentials （ERPs）, the present study aimed to investigate two long-term semantic priming effects to illustrate the common representations involved in WM and LTM. Fifteen college students （mean age=20.33±91; 7 male） participated in the experiment. The participants were all right-hand, had normal or corrected-to-normal vision and had no neurological or psychological disorders. Each participant signed a consent form prior to experiment and was paid after experiment. We combined a WM component （short-term verbal encoding） and a LTM component （category comparison） into one task, so that WM and LTM processing could be concurrently investigated. LTM priming on WM was manipulated by asking participants to learn before short-term verbal encoding, and the priming effect of WM on related LTM should be found in category comparison. Results revealed two long-term semantic priming effects in behavior data and ERPs. The first effect was found in short-term encoding phase, which was reflected as the priming of LTM on WM. Compared with new targets in WM, the reaction time of studied targets was shorter. They elicitedearlier N2 and P3, and they also decreased N2 amplitude. These may index the so-called neural priming （or repetition suppression） of scalp potentials. However, there was no difference between new and studied distractors in WM. Furthermore, the neural priming of WM on LTM also exhibited in category comparison. Specific contents, which were formerly concerned or ignored in short-term encoding phase, led relevant representations of LTM to diverse activation patterns. N400 elicited by target category （items in which were the same category as the targets in short-term encoding phase）was more positive than that of unprimed category, which also index the neural priming of scalp potentials. But this neural priming was modulated by repetation, that is, when target category was relevant to studied targets rather than new ones, the N400 would be more negative. Results indicate that common representations are used both in WM and in LTM, supporting the activation-based model. Furthermore, these results point to the key role of attention as a modulator in the linkage between WM and LTM.