Center for Mind & Brain and Department of Psychology, University of California-Davis, Davis, California, 95618
Center for Mind & Brain and Department of Psychology, University of California-Davis, Davis, California, 95618.
J Neurosci. 2018 Jan 10;38(2):409-422. doi: 10.1523/JNEUROSCI.2860-17.2017. Epub 2017 Nov 22.
In human scalp EEG recordings, both sustained potentials and alpha-band oscillations are present during the delay period of working memory tasks and may therefore reflect the representation of information in working memory. However, these signals may instead reflect support mechanisms rather than the actual contents of memory. In particular, alpha-band oscillations have been tightly tied to spatial attention and may not reflect location-independent memory representations per se. To determine how sustained and oscillating EEG signals are related to attention and working memory, we attempted to decode which of 16 orientations was being held in working memory by human observers (both women and men). We found that sustained EEG activity could be used to decode the remembered orientation of a stimulus, even when the orientation of the stimulus varied independently of its location. Alpha-band oscillations also carried clear information about the location of the stimulus, but they provided little or no information about orientation independently of location. Thus, sustained potentials contain information about the object properties being maintained in working memory, consistent with previous evidence of a tight link between these potentials and working memory capacity. In contrast, alpha-band oscillations primarily carry location information, consistent with their link to spatial attention. Working memory plays a key role in cognition, and working memory is impaired in several neurological and psychiatric disorders. Previous research has suggested that human scalp EEG recordings contain signals that reflect the neural representation of information in working memory. However, to conclude that a neural signal actually represents the object being remembered, it is necessary to show that the signal contains fine-grained information about that object. Here, we show that sustained voltages in human EEG recordings contain fine-grained information about the orientation of an object being held in memory, consistent with a memory storage signal.
在人类头皮 EEG 记录中，持续电位和 alpha 波段振荡都存在于工作记忆任务的延迟期间，因此可能反映了工作记忆中的信息表示。然而，这些信号可能反映的是支持机制，而不是记忆的实际内容。特别是，alpha 波段振荡与空间注意密切相关，可能本身并不反映位置无关的记忆表示。为了确定持续和振荡 EEG 信号如何与注意力和工作记忆相关，我们试图通过人类观察者（包括女性和男性）解码在工作记忆中保持的 16 个方向中的哪一个。我们发现，即使刺激的方向与其位置独立变化，持续 EEG 活动也可以用于解码被记住的刺激的方向。alpha 波段振荡也清楚地携带了关于刺激位置的信息，但它们提供的关于位置的信息很少或没有独立于位置的关于方向的信息。因此，持续电位包含有关在工作记忆中保持的对象属性的信息，这与这些电位与工作记忆能力之间的紧密联系一致。相比之下，alpha 波段振荡主要携带位置信息，与它们与空间注意的联系一致。工作记忆在认知中起着关键作用，并且在几种神经和精神障碍中受损。先前的研究表明，人类头皮 EEG 记录包含反映工作记忆中信息的神经表示的信号。然而，要得出一个神经信号实际上代表了被记住的对象的结论，有必要表明该信号包含有关该对象的细粒度信息。在这里，我们表明人类 EEG 记录中的持续电压包含有关记忆中保持的对象的方向的细粒度信息，与记忆存储信号一致。
