School of Medicine, University College Cork Cork, Ireland ; Department of Psychology, Royal Holloway, University of London Egham, Surrey, UK.
Front Hum Neurosci. 2013 Apr 25;7:154. doi: 10.3389/fnhum.2013.00154. eCollection 2013.
Spatial attention enables us to enhance the processing of items at target locations, at the expense of items presented at irrelevant locations. Many studies have explored the neural correlates of these spatial biases using event-related potentials (ERPs). More recently some studies have shown that these ERP correlates are also present when subjects search visual short-term memory (VSTM). This suggests firstly that this type of mental representation retains a spatial organization that is based upon that of the original percept, and secondly that these attentional biases are flexible and can act to modulate remembered as well as perceptual representations. We aimed to test whether it was necessary for subjects to have actually seen the memoranda at those spatial locations, or whether simply imagining the spatial layout was sufficient to elicit the spatial attention effects. On some trials subjects performed a "visual" search of an array held in VSTM, and upon other trials subjects imagined the items at those spatial locations. We found ERP markers of spatial attention in both the memory-search and the imagery-search conditions. However, there were differences between the conditions, the effect in the memory-search began earlier and included posterior electrode sites. By contrast the ERP effect in the imagery-search condition was apparent only over fronto-central electrode sites and emerged slightly later. Nonetheless, our data demonstrate that it is not necessary for subjects to have ever seen the items at spatial locations for neural markers of spatial attention to be elicited; searching an imaginary spatial layout also triggers spatially-specific attention effects in the ERP data.
空间注意使我们能够增强目标位置项目的处理能力，而牺牲呈现于不相关位置的项目。许多研究使用事件相关电位 (ERP) 探索了这些空间偏差的神经相关性。最近的一些研究表明，当被试搜索视觉短期记忆 (VSTM) 时，这些 ERP 相关性也存在。这首先表明，这种类型的心理表征保留了基于原始感知的空间组织，其次表明这些注意力偏差是灵活的，可以作用于调节记忆和感知的表示。我们旨在测试被试是否有必要在那些空间位置实际看到记忆项，或者仅仅想象空间布局是否足以引起空间注意效应。在一些试验中，被试在 VSTM 中进行了数组的“视觉”搜索，而在其他试验中，被试在那些空间位置想象了项目。我们在记忆搜索和想象搜索条件中都发现了空间注意的 ERP 标记。然而，这些条件之间存在差异，记忆搜索中的效应开始得更早，包括后电极部位。相比之下，想象搜索条件中的 ERP 效应仅在额-中央电极部位明显，并且出现得稍晚。尽管如此，我们的数据表明，对于神经标记的空间注意被引出，被试不必曾经在空间位置看到项目；搜索想象的空间布局也会在 ERP 数据中引发空间特异性的注意效应。
