Responses of auditory cortical neurons to pairs of sounds: correlates of fusion and localization.
Responses of auditory cortical neurons to pairs of sounds: correlates of fusion and localization.
复制标题
听觉皮层神经元对声音对的反应：融合和定位的相关性。
DOI：
10.1152/jn.2001.86.3.1333
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Middlebrooks,JC
中科院分区：
文献类型：
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作者：
Mickey,BJ;Middlebrooks,JC
当两个简短的声音几乎同时从不同的方向到达听者的耳朵时，声音的定位被描述为“优先效应”。在刺激间延迟（ISD）<5 ms时，听众通常报告听到的不是两个声音，而是一个融合的声音。融合图像的报告位置取决于ISD。在1-4 ms的ISD处，听众指向主导源附近（定位优势）。随着ISD从0.8 ms减小到0 ms，融合图像朝向两个源之间的中间位置偏移（求和定位）。当施加刺激间水平差异（ISLD）时，判断转向更强烈的来源。空间听觉，包括优先效应，被认为取决于听觉皮层。因此，我们测试的假设，皮层神经元的活动信号融合的声音对感知的位置。我们记录了麻醉猫皮层A1和A2区神经元的单位反应。单一的宽带点击从不同的正面位置。成对喀喇音通过位于中线左右50°的两个扬声器的各种ISD和ISLD呈现。单元通常对单次点击或成对点击做出反应，并产生单次尖峰脉冲。人工神经网络被训练来识别来自不同位置的单次点击引起的尖峰模式。然后，训练好的网络被用来识别成对点击的单元响应所发出的位置。在1-4 ms的ISD处，单元响应通常用信号通知与定位优势一致的领先源的位置附近的位置。尽管如此，这些反应通常表现出相当大的不足;这一发现也符合心理物理测量。随着ISD从0.4ms减小到0 ms，网络估计通常从领先位置向中线偏移，与求和定位一致。此外，叠加的ISLD使网络估计向更强的源移动，在15-20 dB的ISLD处达到渐近线。为了将我们的生理发现与心理物理学结果进行定量比较，我们进行了人类心理物理学实验，并从猫和人类的耳朵进行了声学测量。考虑到猫和人类头部大小的差异，大脑皮层单位的反应通常与人类听众的反应一致，尽管有相当一部分单位违背了心理物理学的预期。
When two brief sounds arrive at a listener's ears nearly simultaneously from different directions, localization of the sounds is described by “the precedence effect.” At inter-stimulus delays (ISDs) <5 ms, listeners typically report hearing not two sounds but a single fused sound. The reported location of the fused image depends on the ISD. At ISDs of 1–4 ms, listeners point near the leading source (localization dominance). As the ISD is decreased from 0.8 to 0 ms, the fused image shifts toward a location midway between the two sources (summing localization). When an inter-stimulus level difference (ISLD) is imposed, judgements shift toward the more intense source. Spatial hearing, including the precedence effect, is thought to depend on the auditory cortex. Therefore we tested the hypothesis that the activity of cortical neurons signals the perceived location of fused pairs of sounds. We recorded the unit responses of cortical neurons in areas A1 and A2 of anesthetized cats. Single broadband clicks were presented from various frontal locations. Paired clicks were presented with various ISDs and ISLDs from two loudspeakers located 50° to the left and right of midline. Units typically responded to single clicks or paired clicks with a single burst of spikes. Artificial neural networks were trained to recognize the spike patterns elicited by single clicks from various locations. The trained networks were then used to identify the locations signaled by unit responses to paired clicks. At ISDs of 1–4 ms, unit responses typically signaled locations near that of the leading source in agreement with localization dominance. Nonetheless the responses generally exhibited a substantial undershoot; this finding, too, accorded with psychophysical measurements. As the ISD was decreased from ∼0.4 to 0 ms, network estimates typically shifted from the leading location toward the midline in agreement with summing localization. Furthermore a superposed ISLD shifted network estimates toward the more intense source, reaching an asymptote at an ISLD of 15–20 dB. To allow quantitative comparison of our physiological findings to psychophysical results, we performed human psychophysical experiments and made acoustical measurements from the ears of cats and humans. After accounting for the difference in head size between cats and humans, the responses of cortical units usually agreed with the responses of human listeners, although a sizable minority of units defied psychophysical expectations.