Kaiser Jochen, Bertrand Olivier
Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Gartenstrasse 29, 72074 Tübingen, Germany.
Neuroimage. 2003 Aug;19(4):1427-38. doi: 10.1016/s1053-8119(03)00233-7.
Human brain imaging studies have suggested that posterior temporo-parietal regions are involved in auditory spatial processing. We used electroencephalography to investigate the dynamics of temporo-parietal networks during working memory for moving sounds. A delayed matching-to-sample task required a decision on the identity of positions and trajectories of two moving sounds S1 and S2 presented with delays of 927 or 1427 ms. Moving sounds consisted of noise bursts positioned at successive angles to create the impression of one of six possible trajectories at variable spatial positions. Stimuli in the equally difficult control condition were identical to the memory task up to S2, which was replaced by a spatial displacement in the otherwise stationary background sound whose direction had to be detected. Event-related potentials were recorded from 31 scalp electrodes in 15 subjects. Scalp current density estimates allowed to identify the following components. The fronto-central negative variation preceding S2 did not differ between tasks. In contrast, the sustained negative current during the presentation of S1 originating from superior temporal cortex was more pronounced for the memory task, probably reflecting enhanced attention allocation and foreground-background discrimination. Most importantly, the memory task activated current sources over bilateral posterior parietal regions between the middle of S1 and the end of the delay phase. This component was completely absent in the control condition. In summary, the present study disclosed varying degrees of memorization-related, top-down driven influences on the processing of moving sounds at different stages of an auditory network involving temporal and parietal regions.
人类脑成像研究表明，颞顶叶后部区域参与听觉空间处理。我们使用脑电图来研究移动声音工作记忆期间颞顶叶网络的动态变化。一个延迟样本匹配任务要求对两个延迟927或1427毫秒呈现的移动声音S1和S2的位置和轨迹的一致性做出判断。移动声音由位于连续角度的噪声脉冲组成，以在可变空间位置产生六种可能轨迹之一的印象。在难度相同的对照条件下，刺激直到S2都与记忆任务相同，S2被静止背景声音中的空间位移所取代，其方向必须被检测。在15名受试者的31个头皮电极上记录事件相关电位。头皮电流密度估计允许识别以下成分。S2之前的额中央负向变化在任务之间没有差异。相比之下，S1呈现期间起源于颞上皮质的持续负电流在记忆任务中更明显，可能反映了增强的注意力分配和前景-背景辨别。最重要的是，记忆任务在S1中期到延迟阶段结束之间激活了双侧顶叶后部区域的电流源。在对照条件下这个成分完全不存在。总之，本研究揭示了在涉及颞叶和顶叶区域的听觉网络的不同阶段，与记忆相关的自上而下驱动的影响对移动声音处理的不同程度。
