Lewald Jörg
Auditory Cognitive Neuroscience Laboratory, Department of Cognitive Psychology, Ruhr University Bochum, D-44780 Bochum, Germany; Leibniz Research Centre for Working Environment and Human Factors, Ardeystraße 67, D-44139 Dortmund, Germany.
Neuropsychologia. 2016 Apr;84:282-93. doi: 10.1016/j.neuropsychologia.2016.01.030. Epub 2016 Jan 26.
Localizing and selectively attending to the source of a sound of interest in a complex auditory environment is an important capacity of the human auditory system. The underlying neural mechanisms have, however, still not been clarified in detail. This issue was addressed by using bilateral bipolar-balanced transcranial direct current stimulation (tDCS) in combination with a task demanding free-field sound localization in the presence of multiple sound sources, thus providing a realistic simulation of the so-called "cocktail-party" situation. With left-anode/right-cathode, but not with right-anode/left-cathode, montage of bilateral electrodes, tDCS over superior temporal gyrus, including planum temporale and auditory cortices, was found to improve the accuracy of target localization in left hemispace. No effects were found for tDCS over inferior parietal lobule or with off-target active stimulation over somatosensory-motor cortex that was used to control for non-specific effects. Also, the absolute error in localization remained unaffected by tDCS, thus suggesting that general response precision was not modulated by brain polarization. This finding can be explained in the framework of a model assuming that brain polarization modulated the suppression of irrelevant sound sources, thus resulting in more effective spatial separation of the target from the interfering sound in the complex auditory scene.
在复杂的听觉环境中定位并选择性地关注感兴趣声音的来源，是人类听觉系统的一项重要能力。然而，其潜在的神经机制仍未得到详细阐明。本研究通过使用双侧双极平衡经颅直流电刺激（tDCS），结合一项在存在多个声源的情况下要求自由场声音定位的任务，来解决这个问题，从而提供了对所谓“鸡尾酒会”情境的逼真模拟。发现当双侧电极采用左阳极/右阴极（而非右阳极/左阴极）的组合方式时，颞上回（包括颞平面和听觉皮层）的tDCS能提高左半空间目标定位的准确性。在顶下小叶进行tDCS或对用于控制非特异性效应的体感运动皮层进行非靶向主动刺激时，均未发现效果。此外，定位的绝对误差不受tDCS影响，因此表明总体反应精度未受脑极化调节。这一发现可以在一个模型框架内得到解释，该模型假设脑极化调节了对无关声源的抑制，从而在复杂听觉场景中使目标与干扰声音实现更有效的空间分离。
