Liang Tengfei, Hu Zhonghua, Liu Qiang
Research Center of Brain and Cognitive Neuroscience, Liaoning Normal University, Dalian, China.
Front Psychol. 2017 Oct 17;8:1821. doi: 10.3389/fpsyg.2017.01821. eCollection 2017.
During the comparison stage of visual working memory (VWM) processing, detecting the mismatch between the external sensory input and internal representations is a crucial cognitive ability for human, but the neural mechanism behind it remains largely unclear. The present study investigated the role of frontal theta power in detecting the mismatched information in VWM in a delayed matching task. A control task required to compare two simultaneously presented visual figures was also designed as a contrast to exclude the possibility that frontal theta activity just reflecting the non-memory-related behavioral conflicts. To better characterize the control mechanisms shaped by the frontal theta oscillation in human VWM, colored shapes were adopted as materials while both the task-relevant shape feature and task-irrelevant color feature could be mismatched. We found that the response times of participants were significantly delayed under the relevant- and irrelevant-mismatch conditions in both tasks and the conjunction-mismatch condition in delayed matching task. While our EEG data showed that increased frontal theta power was only observed under the relevant- and conjunction-mismatch conditions in the delayed matching task, but not the control task. These findings suggest that the frontal distributed theta activity observed here reflects the detection of mismatched information during the comparison stage of VWM, rather than the response-related conflicts. Furthermore, it is consistent with the proposal that theta-band oscillation can act as a control mechanism in working memory function so that the target-mismatched information in VWM could be successfully tracked. We also propose a possible processing structure to explain the neural dynamics underlying the mismatch detection process in VWM.
在视觉工作记忆（VWM）处理的比较阶段，检测外部感官输入与内部表征之间的不匹配是人类一项至关重要的认知能力，但其背后的神经机制仍 largely不清楚。本研究在一项延迟匹配任务中调查了额叶θ波功率在检测VWM中不匹配信息方面的作用。还设计了一个需要比较两个同时呈现的视觉图形的对照任务作为对比，以排除额叶θ活动仅仅反映与记忆无关的行为冲突的可能性。为了更好地表征人类VWM中由额叶θ振荡形成的控制机制，采用彩色形状作为材料，同时任务相关的形状特征和任务无关的颜色特征都可能不匹配。我们发现，在两个任务的相关和无关不匹配条件以及延迟匹配任务的联合不匹配条件下，参与者的反应时间都显著延迟。而我们的脑电图数据显示，仅在延迟匹配任务的相关和联合不匹配条件下观察到额叶θ波功率增加，而对照任务中未观察到。这些发现表明，这里观察到的额叶分布式θ活动反映了VWM比较阶段不匹配信息的检测，而不是与反应相关的冲突。此外，这与θ波段振荡可以作为工作记忆功能中的一种控制机制，从而使VWM中目标不匹配信息能够被成功追踪的提议一致。我们还提出了一种可能的处理结构来解释VWM中不匹配检测过程背后的神经动力学。
