Agam Yigal, Sekuler Robert
Volen Center for Complex Systems, Brandeis University, USA.
Neuroimage. 2007 Jul 1;36(3):933-42. doi: 10.1016/j.neuroimage.2007.04.014. Epub 2007 Apr 18.
How do working memory and perception interact with each other? Recent theories of working memory suggest that they are closely linked, and in fact share certain brain mechanisms. We used a sequential motion imitation task in combination with EEG and ERP techniques for a direct, online examination of memory load's influence on the processing of visual stimuli. Using a paradigm in which subjects tried to reproduce random motion sequences from memory, we found a systematic decrease in ERP amplitude with each additional motion segment that was viewed and memorized for later imitation. High-frequency (>20 Hz) oscillatory activity exhibited a similar position-dependent decrease. When trials were sorted according to the accuracy of subsequent imitation, the amplitude of the ERPs during stimulus presentation correlated with behavioral performance: the larger the amplitude, the more accurate the subsequent imitation. These findings imply that visual processing of sequential stimuli is not uniform. Rather, earlier information elicits stronger neural activity. We discuss possible explanations for this observation, among them competition for attention between memory and perception and encoding of serial order by means of differential activation strengths.
工作记忆与感知是如何相互作用的？近期的工作记忆理论表明，它们紧密相连，实际上还共享某些脑机制。我们运用了序列运动模仿任务，并结合脑电图（EEG）和事件相关电位（ERP）技术，对记忆负荷对视觉刺激处理的影响进行直接的在线检测。采用一种范式，让受试者尝试从记忆中重现随机运动序列，我们发现，随着每一个额外的被观看并记忆以供后续模仿的运动片段，ERP波幅会系统性降低。高频（>20赫兹）振荡活动也呈现出类似的与位置相关的降低。当根据后续模仿的准确性对试验进行分类时，刺激呈现期间ERP的波幅与行为表现相关：波幅越大，后续模仿就越准确。这些发现意味着，对序列刺激的视觉处理并非是均匀的。相反，早期信息会引发更强的神经活动。我们讨论了对此观察结果的可能解释，其中包括记忆与感知之间对注意力的竞争以及通过不同激活强度对序列顺序进行编码。
