Wascher E, Reinhard M, Wauschkuhn B, Verleger R
Department Clin & Psyciol. Psychology, Christophstr.2, D-72072 Tubingen GERMANY.
J Cogn Neurosci. 1999 Mar;11(2):214-29. doi: 10.1162/089892999563346.
Lateral presentation of relevant information facilitates manual responses if the side of relevant information corresponds to the side of the response. Recently, temporally overlapping EEG asymmetries over the central motor cortex and posterior sites were reported as a possible correlate of the sensory-motor integration of spatial information. The present study investigated whether sensory-motor integration of spatial information can occur with symbolic spatial information the same way as with laterally presented stimuli. The task required participants to respond to arrows (target stimuli), which were "flanked" (from above and below) by neutral stimuli or by other arrows (compatible or not). In Experiment 1, this task was compared to the same task with letters as stimuli and to an incompatible task where participants had to respond "against" the arrow direction. The effect of the flankers on response times was largest if subjects had to respond to the arrows in the common way. This was also the only task of Experiment 1 for which marked EEG asymmetries related to the direction of the flankers were observed. In Experiment 2, the onsets of target stimulus and flankers differed in time. Event-related lateralizations of the EEG over sensory and primary motor areas--as a lateralized readiness potential--were always, apparently automatically, evoked by flanking arrows, indicating automatic response activation evoked by symbolic spatial information. In accordance to recent theories of temporally decaying response activation, manual responses were affected only if the target was either shortly preceded by or appeared simultaneously with the flankers. The temporal overlap of EEG asymmetries related to direction encoding, automatic response activation, and to response preparation indicated that a widespread cortical network is activated by a salient directional information that enables subjects to respond quickly if the directional code of the stimulus overlaps with the directional code of the response.
如果相关信息的一侧与反应的一侧相对应，那么相关信息的横向呈现便于手动反应。最近，有报道称，中央运动皮层和后部区域在时间上重叠的脑电图不对称可能是空间信息感觉运动整合的一个相关因素。本研究调查了空间信息的感觉运动整合是否能以与横向呈现刺激相同的方式发生在符号空间信息上。该任务要求参与者对箭头（目标刺激）做出反应，箭头由中性刺激或其他箭头（兼容或不兼容）从上方和下方“侧翼”包围。在实验1中，将此任务与以字母为刺激的相同任务以及参与者必须“逆”箭头方向做出反应的不兼容任务进行比较。如果受试者必须以通常方式对箭头做出反应，侧翼刺激对反应时间的影响最大。这也是实验1中唯一观察到与侧翼刺激方向相关的明显脑电图不对称的任务。在实验2中，目标刺激和侧翼刺激的起始时间不同。脑电图在感觉和初级运动区域的事件相关侧化——作为一种侧化准备电位——总是明显自动地由侧翼箭头诱发，表明符号空间信息诱发了自动反应激活。根据最近关于时间衰减反应激活理论，只有当目标刺激之前不久或与侧翼刺激同时出现时，手动反应才会受到影响。与方向编码、自动反应激活和反应准备相关的脑电图不对称的时间重叠表明，一个广泛的皮层网络被显著的方向信息激活，这使得受试者在刺激的方向代码与反应的方向代码重叠时能够快速做出反应。
