The LINE (Laboratory for Investigative Neurophysiology), Radiology Department, University Hospital Center and University of Lausanne, 1011, Lausanne, Switzerland; The EEG Brain Mapping Core, Center for Biomedical Imaging (CIBM), University Hospital Center and University of Lausanne, 1011, Lausanne, Switzerland.
The LINE (Laboratory for Investigative Neurophysiology), Radiology Department, University Hospital Center and University of Lausanne, 1011, Lausanne, Switzerland; Information Systems Institute at the University of Applied Sciences Western Switzerland (HES-SO Valais), 3960, Sierre, Switzerland; Department of Hearing and Speech Sciences, Vanderbilt University, Nashville, TN, USA.
Neuropsychologia. 2020 Jul;144:107498. doi: 10.1016/j.neuropsychologia.2020.107498. Epub 2020 May 20.
Contemporary schemas of brain organization now include multisensory processes both in low-level cortices as well as at early stages of stimulus processing. Evidence has also accumulated showing that unisensory stimulus processing can result in cross-modal effects. For example, task-irrelevant and lateralised sounds can activate visual cortices; a phenomenon referred to as the auditory-evoked contralateral occipital positivity (ACOP). Some claim this is an example of automatic attentional capture in visual cortices. Other results, however, indicate that context may play a determinant role. Here, we investigated whether selective attention to spatial features of sounds is a determining factor in eliciting the ACOP. We recorded high-density auditory evoked potentials (AEPs) while participants selectively attended and discriminated sounds according to four possible stimulus attributes: location, pitch, speaker identity or syllable. Sound acoustics were held constant, and their location was always equiprobable (50% left, 50% right). The only manipulation was to which sound dimension participants attended. We analysed the AEP data from healthy participants within an electrical neuroimaging framework. The presence of sound-elicited activations of visual cortices depended on the to-be-discriminated, goal-based dimension. The ACOP was elicited only when participants were required to discriminate sound location, but not when they attended to any of the non-spatial features. These results provide a further indication that the ACOP is not automatic. Moreover, our findings showcase the interplay between task-relevance and spatial (un)predictability in determining the presence of the cross-modal activation of visual cortices.
当代的大脑组织模式现在包括低水平皮层中的多感官过程以及刺激处理的早期阶段。也有证据表明，单一感官刺激处理会导致跨模态效应。例如，与任务无关的和侧化的声音可以激活视觉皮层；这种现象被称为听觉诱发对侧枕部正性（ACOP）。有人认为这是视觉皮层自动注意力捕获的一个例子。然而，其他结果表明，上下文可能起着决定性的作用。在这里，我们研究了选择性注意声音的空间特征是否是引起 ACOP 的决定因素。当参与者根据四个可能的刺激属性（位置、音高、说话者身份或音节）选择性地注意和区分声音时，我们记录了高密度听觉诱发电位（AEPs）。声音的声学特性保持不变，其位置总是等概率的（50%在左边，50%在右边）。唯一的操作是参与者关注的声音维度。我们在电神经成像框架内分析了健康参与者的 AEP 数据。视觉皮层的声音诱发激活的存在取决于基于目标的待区分维度。只有当参与者被要求区分声音位置时，才会引起 ACOP，但当他们关注任何非空间特征时，则不会引起 ACOP。这些结果进一步表明 ACOP 不是自动的。此外，我们的研究结果展示了任务相关性和空间（非）可预测性在确定视觉皮层的跨模态激活中的相互作用。
