Research On Event-related Potentials Based On N-back Paradigm Working Memory

This paper is to investigate the character of activated functional regions for different working memory loads and separate the neuroelectrophysiological outcome among different working memory process. The study used three lever loads(0-back, 1-back, 2-back) of the n-back paradigm with the single random capital consonant letters as trail material. E-Prime was used for presenting stimulus and collecting behavioral data. The EEG signal was collected by 64 leads acquisition system. Compare the behavior data and EEG signals of different loads dynamically, then discuss its' time course and characteristic of area distribution after pretreatment. The method of event-related potential(ERP) is used to separate the neuroelectrophysiological outcome among different working memory process. The Outcome Measurement was analyzed with 3-factor repeated measures analysis of variance.The result:1. The accuracy and response time have significant difference during different task. The accuracy will be decreased and the respond time will be prolonged with the increasing of working memory load.2. The evoked P300 component, occurred in three different task, is the obvious element in ERP during working memory task. The main effect of different memory load is significant. The average amplitude of P300 in 1-back task is higher than that in 0-back and 2-back. The effect for hemisphere is significant. The average amplitude of P300 in left regions is lower than center and right regions, which indicate the hyperfunction in right hemisphere. The two-way interaction of load×site-location is significant, and it presents an increased frontal activity in 2-back task, an increased central activity in 1-back, accompanied with the decrease of parietal regions.3. The difference waves(2-back minus 0-back and 1-back minus 0-back) present a significant P800 component, which mainly occurs in prefrontal regions during 700 ms-900 ms. As to P800 component, the main effect of load is significant. When the load increased, the difference level for P800 will be enhanced. The effect of site-location is significant. The amplitude of P800 is decreased from parietal regions to frontal regions consecutively. The two-way interaction of load×site-location is significant. The increased quantity of frontal regions in 2-0 task is higher than that in 1-0 task. The latency of P800 component is significant for difference load. And with the increasing of memory load, the latency will be prolonged.With the increasing of working memory task load, the participants overall function output efficiency decline gradually: the accuracy decrease and the reaction time extend. The P300 component of different working memory load has significant differences. With the increasing of the task load, the P300 component main active region move to the forehead. Difference wave P800 component is associated with updating and stored process and mainly located in the frontal, increased significantly with the increase of load amplitude, reflect the working memory updating and stored procedures. When the load enhanced, the amplitude of P800 will be increased.