Leiberg Susanne, Kaiser Jochen, Lutzenberger Werner
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, MEG Center, Otfried-Müller-Str. 47, 72076 Tübingen, Germany.
Neuroimage. 2006 May 1;30(4):1357-64. doi: 10.1016/j.neuroimage.2005.11.010. Epub 2006 Feb 15.
Electro- and magnetoencephalography studies have suggested that increased gamma-band activity (GBA) is a correlate of activated neural stimulus representations. In this study, a delayed matching-to-sample paradigm for auditory spatial information was employed to investigate the role of magnetoencephalographic gamma-band activity in the differentiation between matching and nonmatching stimulus pairs. Twelve subjects made same-different judgments about the lateralization angle of pairs of filtered noise stimuli (S1 and S2) presented with 0.8-s delays. One half of the subjects had to respond to matching stimulus pairs, the other half to nonmatching stimulus pairs. Cortical oscillatory activity in the memory task was compared to a control task requiring the detection of background noise intensity changes. Memory-related GBA increases were revealed over midline parietal areas in the middle of the delay phase and during the presentation of S2 and over frontocentral areas at the end of the delay phase. This replicated previous findings. In addition, nonmatching trials were associated with increased GBA over right parietal areas in response to S2. The midline parietal GBA increase during S2 in the memory condition may have reflected the representation of S1 needed for a comparison between S1 and S2. When S1 and S2 were identical, no further representation was required. In contrast, for nonmatching pairs, a second representation was activated over right parietal areas.
脑电图和脑磁图研究表明，γ波段活动增强（GBA）与激活的神经刺激表征相关。在本研究中，采用了一种用于听觉空间信息的延迟样本匹配范式，以研究脑磁图γ波段活动在匹配和不匹配刺激对区分中的作用。12名受试者对呈现延迟0.8秒的滤波噪声刺激对（S1和S2）的侧向化角度做出相同或不同的判断。一半受试者必须对匹配的刺激对做出反应，另一半对不匹配的刺激对做出反应。将记忆任务中的皮层振荡活动与要求检测背景噪声强度变化的对照任务进行比较。在延迟阶段中期、S2呈现期间，中线顶叶区域以及延迟阶段结束时额中央区域出现了与记忆相关的GBA增加。这重复了先前的研究结果。此外，在不匹配试验中，对S2的反应与右侧顶叶区域GBA增加有关。在记忆条件下，S2期间中线顶叶GBA增加可能反映了S1与S2比较所需的S1表征。当S1和S2相同时，不需要进一步的表征。相比之下，对于不匹配的刺激对，右侧顶叶区域会激活第二种表征。
