Institute of Cognitive Neuroscience, University College London (UCL), London, UK.
Cortex. 2013 Sep;49(8):2239-48. doi: 10.1016/j.cortex.2012.10.011. Epub 2012 Nov 9.
Effective cognitive functioning not only relies on brain activity elicited by an event, but also on activity that precedes it. This has been demonstrated in a number of cognitive domains, including memory. Here, we show that brain activity that precedes the effective encoding of a word into long-term memory depends on the availability of sufficient processing resources. We recorded electrical brain activity from the scalps of healthy adult men and women while they memorized intermixed visual and auditory words for later recall. Each word was preceded by a cue that indicated the modality of the upcoming word. The degree to which processing resources were available before word onset was manipulated by asking participants to make an easy or difficult perceptual discrimination on the cue. Brain activity before word onset predicted later recall of the word, but only in the easy discrimination condition. These findings indicate that anticipatory influences on long-term memory are limited in capacity and sensitive to the degree to which attention is divided between tasks. Prestimulus activity that affects later encoding can only be engaged when the necessary cognitive resources can be allocated to the encoding process.
有效的认知功能不仅依赖于事件引发的大脑活动，还依赖于事件发生之前的活动。这在许多认知领域都得到了证明，包括记忆。在这里，我们表明，在将一个单词有效地编码为长期记忆之前的大脑活动取决于是否有足够的处理资源。我们记录了健康成年男性和女性头皮的电脑活动，同时他们记忆混合的视觉和听觉单词以备稍后回忆。每个单词都有一个提示，提示即将到来的单词的模态。通过要求参与者在提示上进行简单或困难的感知辨别，来操纵单词出现之前处理资源的可用性程度。单词出现前的大脑活动可以预测单词的后续回忆，但仅在简单的辨别条件下。这些发现表明，对长期记忆的预期影响是有限的，并且对注意力在任务之间的分配程度很敏感。只有当必要的认知资源可以分配给编码过程时，才能参与影响后续编码的预刺激活动。
