Yu Xiaolin, Chen Youguo, Luo Ting, Huang Xiting
School of Education Science, Jiangsu Normal University, Xuzhou, China.
Faculty of Psychology, Southwest University, Chongqing, China.
Front Psychol. 2020 Sep 3;11:545935. doi: 10.3389/fpsyg.2020.545935. eCollection 2020.
The neural representation of the external events duration in working memory (WM) remains to be understood. It has been reported that there were different neural representations below and above 3 s/2 s for visual/auditory duration, respectively. However, these studies had limitations in experimental design, i.e., the interference of task difficulty was not assessed. Consequently, the results of these studies require verification. In the present study, we eliminated these limitations using an exploratory experiment in which the probe stimulus conditions were reset, while the other settings remained similar to those used in previous studies. In the exploratory experiment, we found that accuracy and reaction times were comparable among all the four duration conditions, suggesting that task difficulty was accurately matched. In the formal experiment, theta and alpha oscillations were examined using electroencephalogram recordings during the maintenance of the auditory duration in working memory, after removing the interference of task difficulty. Electroencephalogram results indicated that there were no significant differences in theta band power among different length of durations retained in working memory, whereas the alpha band power was significantly lower in the 3-s and 4-s duration conditions than in the 1-s and 2-s conditions. The findings suggest that different internal representations of auditory durations above and below the 2-s threshold are maintained in working memory. Also, our study provides evidence that the duration representation segmentation is associated with the length of the auditory duration retained in working memory, but not with task difficulty.
工作记忆（WM）中外部事件持续时间的神经表征仍有待了解。据报道，视觉/听觉持续时间分别在3秒/2秒以下和以上存在不同的神经表征。然而，这些研究在实验设计上存在局限性，即未评估任务难度的干扰。因此，这些研究的结果需要验证。在本研究中，我们通过一项探索性实验消除了这些局限性，在该实验中重新设置了探测刺激条件，而其他设置与先前研究中使用的设置相似。在探索性实验中，我们发现所有四种持续时间条件下的准确性和反应时间相当，这表明任务难度得到了精确匹配。在正式实验中，在消除任务难度干扰后，使用脑电图记录在工作记忆中维持听觉持续时间期间检查θ波和α波振荡。脑电图结果表明，工作记忆中保留的不同持续时间长度的θ波段功率没有显著差异，而在3秒和4秒持续时间条件下的α波段功率明显低于1秒和2秒条件下的。这些发现表明，2秒阈值以上和以下的听觉持续时间的不同内部表征在工作记忆中得以维持。此外，我们的研究提供了证据，表明持续时间表征分割与工作记忆中保留的听觉持续时间长度有关，而与任务难度无关。
