网络成瘾者工作记忆水平受影响的机制:来自ERP的证据

本研究采用事件相关电位技术(ERP),以N-back范式为实验任务,考察20名网络成瘾大学生和23名对照组大学生的工作记忆水平,结果发现:对照组的工作记忆具有一定加工优势的趋势,正确率高于成瘾组,反应时低于成瘾组,但均未达到显著差异。网络成瘾组与对照组工作记忆加工时,网络成瘾组P2波幅更高,N2波幅更低,N2潜伏期更长,说明与网络成瘾组相比,对照组工作记忆水平更高。

The Brain Mechanism on Working Memory Level of Internet Addicts:From the Evidence of ERP

Internet Addiction Disorder (IAD) is a kind of pathological internet using. It features in overusing or uncontrolled using internet and thus has a negative effect on mentality, society and working. The number of people who has IAD is increasing rapidly. There is a growing concern on IAD because of its dangerous. Relevant researches on IAD are urgently required. The scholars did a lot of researches on the neural mechanism of IAD in recent years and found out that IAD had different kinds of brain dysfunction. The abnormality in working memory is one of those dysfunctions. Based on event-related potentials (ERP), the paper discusses the effects of working memory on executive control for IAD and compares the differences between the IAD group and control group on working memory level. The various patterns of ERP time course under increasing memory loads are studied.Employing the technology of ERP, setting N-back model as research task, using letters as material, dividing the tasks into three load levels: 0, 1, 2. The whole experiment was divided into practice and formal experiments. To assure subject understand the experiment, practice experiments include three load levels that required subjects complete. After that, subjects accomplished the formal experiment. Formal experiment contained 8 blocks. Each block contained three load levels, and each memory load had 20 trials. Before the start of each memory load, it will appear a empty screen for 2000ms (n = 0, n = 1, n = 2), and then subjects should response to the letter presented as quickly as possible. Participants had 2 minutes to rest after completing every block. The experiment will last about half an hour. 20 subjects with IAD were selected as the IAD group and another 23 normal college students as control group by using Young’s Internet Addiction Scale to measure their network addition level. We used SPSS 17.0 to process the data.We used the method of 2×3 repeated measure analysis of variances to analyze the behavioral data, and use 2×3×9 repeated measure analysis of variances to analyze the ERP data. The analyzed ERP components mainly include P2, N2. The study purpose is to find out the brain mechanism on the working memory of internet addicts by comparing the ERP components between two groups.Based on the analyses and discussions of the above-mentioned studies, following conclusions were drawn: (1) With the increase of memory load, the accuracy rate declined and the reaction time become longer both IAD and control groups. Compared with IAD group, the college students in control group have processing advantages on the working memory task. Their accuracy rate is higher and their reaction time is shorter than those in IAD group. However, the differences do not reach significance.(2) There are significant differences in P2 and N2 components between the IAD group and the control group. Compared with the control group, the average amplitude of P2 is larger while the average amplitude of N2 is smaller in the IAD group. This reflects that the IAD group need more cognitive resources for working memory processing to get the same achievements than the control group. In the mean time, it also demonstrates that the executive control ability of IAD group is lower than control group. The latency of N2 in the IAD group is longer than control group, which indicates the refresh and time needed for short-term storage in the IAD group are higher than the control group.