Van Wanrooij Marc M, Bell Andrew H, Munoz Douglas P, Van Opstal A John
Department of Biophysics, Donders Institute of Brain, Cognition and Behaviour, Radboud University Nijmegen, 6525 EZ Nijmegen, The Netherlands.
Exp Brain Res. 2009 Sep;198(2-3):425-37. doi: 10.1007/s00221-009-1815-4. Epub 2009 May 5.
In a previous study we quantified the effect of multisensory integration on the latency and accuracy of saccadic eye movements toward spatially aligned audiovisual (AV) stimuli within a rich AV-background (Corneil et al. in J Neurophysiol 88:438-454, 2002). In those experiments both stimulus modalities belonged to the same object, and subjects were instructed to foveate that source, irrespective of modality. Under natural conditions, however, subjects have no prior knowledge as to whether visual and auditory events originated from the same, or from different objects in space and time. In the present experiments we included these possibilities by introducing various spatial and temporal disparities between the visual and auditory events within the AV-background. Subjects had to orient fast and accurately to the visual target, thereby ignoring the auditory distractor. We show that this task belies a dichotomy, as it was quite difficult to produce fast responses (<250 ms) that were not aurally driven. Subjects therefore made many erroneous saccades. Interestingly, for the spatially aligned events the inability to ignore auditory stimuli produced shorter reaction times, but also more accurate responses than for the unisensory target conditions. These findings, which demonstrate effective multisensory integration, are similar to the previous study, and the same multisensory integration rules are applied (Corneil et al. in J Neurophysiol 88:438-454, 2002). In contrast, with increasing spatial disparity, integration gradually broke down, as the subjects' responses became bistable: saccades were directed either to the auditory (fast responses), or to the visual stimulus (late responses). Interestingly, also in this case responses were faster and more accurate than to the respective unisensory stimuli.
在之前的一项研究中，我们量化了多感官整合对在丰富视听背景下朝向空间对齐的视听（AV）刺激的扫视眼动潜伏期和准确性的影响（科尼尔等人，《神经生理学杂志》88:438 - 454，2002年）。在那些实验中，两种刺激模态属于同一物体，并且指示受试者注视该源，而不考虑模态。然而，在自然条件下，受试者对于视觉和听觉事件是源自空间和时间上的同一物体还是不同物体并无先验知识。在本实验中，我们通过在视听背景内引入视觉和听觉事件之间的各种空间和时间差异来涵盖这些可能性。受试者必须快速且准确地朝向视觉目标定向，从而忽略听觉干扰物。我们发现这项任务掩盖了一种二分法，因为要做出不受听觉驱动的快速反应（<250毫秒）相当困难。因此，受试者做出了许多错误的扫视。有趣的是，对于空间对齐的事件，无法忽略听觉刺激产生了更短的反应时间，但也比单感官目标条件下的反应更准确。这些表明有效多感官整合的发现与之前的研究相似，并且应用了相同的多感官整合规则（科尼尔等人，《神经生理学杂志》88:438 - 454，2002年）。相比之下，随着空间差异的增加，整合逐渐瓦解，因为受试者的反应变得双稳态：扫视要么指向听觉刺激（快速反应），要么指向视觉刺激（延迟反应）。有趣的是，在这种情况下，反应也比相应的单感官刺激更快且更准确。
