The Neural Mechanism Of Inhibiting Distractors In Working Memory

Working memory plays a crucial role in information and task processing. The limitation of working memory, in capacity or in quality, makes both successful retention of relevant information and efficient suppression of distracting information very important. Previous studies paid more attention to how interference influenced working memory capacity. But whether the working memory quality will be influenced and its neural mechanism is unclear. In the present study, we explored the influence of interference on working memory precision, and the related neural mechanisms.Present study was based on color task of "recall paradigm". Memory item and interference item were presented on two sides of perspectives and a valid cue for attention was set before stimulus (Cue left or cue right). Then 3 levels of interference were presented on non-attention side at the same time. According to the similarity of working memory item, interferences were divided into 3 levels:low, medium and high. In experiment one,22 participants finished the block design (different block of working memory load 2,4 and 6). EEG was recorded. In experiment two,16 participants finished the mixed task (working memory load 2 and 4 in same block).Experiment one found that:When working memory load was 4 and 6. different levels of interference lead to significant difference of working memory precision. When working memory load was 4, working memory precision showed best performance in low interference level, which was significant different from medium and high level. Alpha power (9-12Hz) in parietal-occipital region during working memory retention (350 ms after stimulus present to end of retention) showed significant differences between ipsilateral and contralateral. And the stimulus ipsilateral (contralateral to distractor) Alpha energy was relatively high while the stimulus contralateral (ipsilateral to distractor) Alpha energy is relatively low. When working memory load was 4, Alpha shows lowest power in low interference level, which is significant different from medium and high level. Ipsilateral Alpha showed different levels of inhibition according to interference level, which showed the same pattern of behavior. During working memory encoding, Theta power (4-8Hz) in parietal-occipital region increased with the item of working memory.Experiment two mixed two working memory load. Results showed that when working memory load is high (4), working memory precision still showed best performance in low interference level.Present study first found that different levels of interference showed corresponding impact on working memory precision only on high working memory load. When working memory load was low, cognitive resource is enough to inhibit interference. The inhibition role of EEG Alpha maybe involved in processing. The study provides new idea for the research of inhibition interference in working memory. More study focused on causal relationship can be carried on in future.