Hearing Research Center, Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America.
PLoS Biol. 2012;10(5):e1001319. doi: 10.1371/journal.pbio.1001319. Epub 2012 May 1.
Why is spatial tuning in auditory cortex weak, even though location is important to object recognition in natural settings? This question continues to vex neuroscientists focused on linking physiological results to auditory perception. Here we show that the spatial locations of simultaneous, competing sound sources dramatically influence how well neural spike trains recorded from the zebra finch field L (an analog of mammalian primary auditory cortex) encode source identity. We find that the location of a birdsong played in quiet has little effect on the fidelity of the neural encoding of the song. However, when the song is presented along with a masker, spatial effects are pronounced. For each spatial configuration, a subset of neurons encodes song identity more robustly than others. As a result, competing sources from different locations dominate responses of different neural subpopulations, helping to separate neural responses into independent representations. These results help elucidate how cortical processing exploits spatial information to provide a substrate for selective spatial auditory attention.
为什么听觉皮层的空间调谐很弱，尽管在自然环境中位置对于目标识别很重要？这个问题一直困扰着专注于将生理结果与听觉感知联系起来的神经科学家。在这里，我们表明，同时存在的竞争声源的空间位置极大地影响了从斑胸草雀场 L（哺乳动物初级听觉皮层的模拟物）记录的神经尖峰序列对声源身份的编码能力。我们发现，在安静环境中播放鸟鸣声对歌曲的神经编码保真度几乎没有影响。但是，当歌曲与掩蔽声一起呈现时，空间效应非常明显。对于每种空间配置，一部分神经元比其他神经元更能可靠地编码歌曲的身份。因此，来自不同位置的竞争声源主导着不同神经元亚群的反应，有助于将神经反应分离成独立的表示。这些结果有助于阐明皮层处理如何利用空间信息为选择性空间听觉注意提供基础。
