Lang S, Kotchoubey B, Lutz A, Birbaumer N
Institut für Medizinische Psychologie und Verhaltensneurobiologie, Universität Tübingen.
Z Exp Psychol. 1997;44(1):138-62.
Two experiments, an "active" and a "passive" oddball-paradigm (1. phase) with visual and auditive stimuli were performed. In both, two stimuli with a probability of 0.7/0.3 were presented. The oddball-sequence was replaced in the 2. phase without knowledge of the subjects by a sequence, in which only targets were presented. One group of the subjects has got an active task (counting the rare stimulus), the other group was told to view the stimuli passively. The rare stimulus in the oddball-sequence evoked a larger parietal P3, the auditive stimulation additionally a larger fronto-central N1 and the visual stimulation a larger central P2. The non-expected change into the 2. phase resulted in a reverse of the ERP-lateralization between 150-300 ms: Before the change of the probability the amplitudes were more negative left than right, thereafter more negative right than left. All components and effects in the active task maintained without task, but they decreased. The differences were larger with the visual stimuli. These results suggest, that the passive paradigm could be applied to patients with motoric deficits. From a theoretical point of view these results lead to certain difficulties in the interpretation of the functional importance of the P3. It can be explained better by the context-closure theory (Desmedt, 1980; Verleger, 1988) than by the context-updating theory (Donchin, 1981).
进行了两项实验，一项是“主动”的，另一项是“被动”的视觉和听觉刺激的oddball范式（第1阶段）。在这两项实验中，呈现两种概率为0.7/0.3的刺激。在第2阶段，在受试者不知情的情况下，将oddball序列替换为仅呈现目标的序列。一组受试者接受了主动任务（对稀有刺激进行计数），另一组被告知被动观看刺激。oddball序列中的稀有刺激诱发了更大的顶叶P3，听觉刺激还诱发了更大的额中央N1，视觉刺激诱发了更大的中央P2。向第2阶段的意外变化导致150 - 300毫秒之间ERP偏侧化的逆转：在概率变化之前，左侧的振幅比右侧更负，此后右侧比左侧更负。主动任务中的所有成分和效应在无任务情况下保持，但有所下降。视觉刺激时差异更大。这些结果表明，被动范式可应用于有运动缺陷的患者。从理论角度来看，这些结果在解释P3的功能重要性方面存在一定困难。用情境闭合理论（德斯梅特，1980；韦尔勒格，1988）比用情境更新理论（唐钦，1981）能更好地解释。
