Tiitinen Hannu, Salminen Nelli H, Palomäki Kalle J, Mäkinen Ville T, Alku Paavo, May Patrick J C
Apperception & Cortical Dynamics (ACD), Cognitive Science, Department of Psychology, P.O. Box 9, FIN-00014 University of Helsinki, Finland.
Neurosci Lett. 2006 Mar 20;396(1):17-22. doi: 10.1016/j.neulet.2005.11.018. Epub 2005 Dec 15.
In an attempt to delineate the assumed 'what' and 'where' processing streams, we studied the processing of spatial sound in the human cortex by using magnetoencephalography in the passive and active recording conditions and two kinds of spatial stimuli: individually constructed, highly realistic spatial (3D) stimuli and stimuli containing interaural time difference (ITD) cues only. The auditory P1m, N1m, and P2m responses of the event-related field were found to be sensitive to the direction of sound source in the azimuthal plane. In general, the right-hemispheric responses to spatial sounds were more prominent than the left-hemispheric ones. The right-hemispheric P1m and N1m responses peaked earlier for sound sources in the contralateral than for sources in the ipsilateral hemifield and the peak amplitudes of all responses reached their maxima for contralateral sound sources. The amplitude of the right-hemispheric P2m response reflected the degree of spatiality of sound, being twice as large for the 3D than ITD stimuli. The results indicate that the right hemisphere is specialized in the processing of spatial cues in the passive recording condition. Minimum current estimate (MCE) localization revealed that temporal areas were activated both in the active and passive condition. This initial activation, taking place at around 100 ms, was followed by parietal and frontal activity at 180 and 200 ms, respectively. The latter activations, however, were specific to attentional engagement and motor responding. This suggests that parietal activation reflects active responding to a spatial sound rather than auditory spatial processing as such.
为了描绘假定的“什么”和“哪里”处理流，我们通过在被动和主动记录条件下使用脑磁图，并采用两种空间刺激来研究人类皮层中空间声音的处理：单独构建的、高度逼真的空间（3D）刺激和仅包含双耳时间差（ITD）线索的刺激。发现事件相关场的听觉P1m、N1m和P2m反应对方位平面中声源的方向敏感。一般来说，右半球对空间声音的反应比左半球更明显。对于对侧声源，右半球的P1m和N1m反应峰值出现得比对侧半视野中的声源更早，并且所有反应的峰值幅度在对侧声源处达到最大值。右半球P2m反应的幅度反映了声音的空间程度，对于3D刺激是ITD刺激的两倍。结果表明，在被动记录条件下，右半球专门处理空间线索。最小电流估计（MCE）定位显示，颞叶区域在主动和被动条件下均被激活。这种初始激活发生在大约100毫秒左右，随后分别在180毫秒和200毫秒时出现顶叶和额叶活动。然而，后者的激活特定于注意力参与和运动反应。这表明顶叶激活反映了对空间声音的主动反应，而不是听觉空间处理本身。
