Decoding neural responses to temporal cues for sound localization.
Decoding neural responses to temporal cues for sound localization.
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DOI：
10.7554/elife.01312
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发表时间：
2013-12-03
期刊：
影响因子：
7.7
通讯作者：
Brette R
中科院分区：
文献类型：
--
作者：
Goodman DF;Benichoux V;Brette R
感觉神经群的活动携带着关于环境的信息。这可以使用不同的策略从神经活动中提取。在听觉脑干中，最近的一个理论提出，声音在水平面上的位置是从每个半球两个群体的相对总和活动中解码出来的，而早期的理论则假设位置是从最活跃的细胞的身份中解码出来的。我们测试了各种解码器的神经反应在日益复杂的声学情况下，包括频谱变化，噪声和声音衍射的性能。我们证明，有没有足够的信息，在每个半球的汇集活动，以一种可靠的方式与行为一致的声音方向估计，而强大的估计，可以从神经活动考虑到异质调谐的细胞。这些估计仍然可以获得时，只使用对侧神经反应，一致的单侧病变的研究。http://dx.doi.org/10.7554/eLife.01312.001拥有两只耳朵可以让动物定位声音的来源。例如，仓鸮可以在完全黑暗的情况下仅依靠声音就能抓住猎物。很长一段时间以来，人们都知道这种能力取决于到达每只耳朵的声音的微小差异，包括到达时间的差异：例如，在人类中，声音到达离声源较近的耳朵比到达另一只耳朵早半毫秒。这些差异被称为耳间时差。然而，大脑处理这些信息以找出声音来自何处的方式一直是许多争论的根源。关于大脑如何通过两耳间的时间差来计算位置，已经提出了几种理论。根据半球理论，大脑两侧特定双耳敏感神经元的活动被加在一起：以这种方式添加信号已被证明可以在简单可控的情况下最大限度地提高对时间差异的敏感性。峰值解码理论提出，大脑可以根据神经元对声音的反应最强烈来计算声音的位置。这两种理论都有其潜在的优势，并且都有证据支持。现在，古德曼等人已经使用计算机模拟来比较生态相关环境下的模型。模拟结果显示，这两种模型预测的结果与在真实的动物身上观察到的结果不一致，他们提出大脑必须使用完整的神经反应模式来计算声音的位置。大脑中负责定位声音的部分之一是下丘。对猫和人类的研究表明，大脑一侧的下丘受损会阻止对身体另一侧声音的准确定位，但动物仍然能够定位同一侧的声音。这一发现很难用半球模型来解释，但古德曼等人表明，它可以用基于模式的模型来解释。DOI：http://dx.doi.org/10.7554/eLife.01312.002网站
The activity of sensory neural populations carries information about the environment. This may be extracted from neural activity using different strategies. In the auditory brainstem, a recent theory proposes that sound location in the horizontal plane is decoded from the relative summed activity of two populations in each hemisphere, whereas earlier theories hypothesized that the location was decoded from the identity of the most active cells. We tested the performance of various decoders of neural responses in increasingly complex acoustical situations, including spectrum variations, noise, and sound diffraction. We demonstrate that there is insufficient information in the pooled activity of each hemisphere to estimate sound direction in a reliable way consistent with behavior, whereas robust estimates can be obtained from neural activity by taking into account the heterogeneous tuning of cells. These estimates can still be obtained when only contralateral neural responses are used, consistently with unilateral lesion studies. DOI: http://dx.doi.org/10.7554/eLife.01312.001 Having two ears allows animals to localize the source of a sound. For example, barn owls can snatch their prey in complete darkness by relying on sound alone. It has been known for a long time that this ability depends on tiny differences in the sounds that arrive at each ear, including differences in the time of arrival: in humans, for example, sound will arrive at the ear closer to the source up to half a millisecond earlier than it arrives at the other ear. These differences are called interaural time differences. However, the way that the brain processes this information to figure out where the sound came from has been the source of much debate. Several theories have been proposed for how the brain calculates position from interaural time differences. According to the hemispheric theory, the activities of particular binaurally sensitive neurons in each of side of the brain are added together: adding signals in this way has been shown to maximize sensitivity to time differences under simple, controlled circumstances. The peak decoding theory proposes that the brain can work out the location of a sound on the basis of which neurons responded most strongly to the sound. Both theories have their potential advantages, and there is evidence in support of each. Now, Goodman et al. have used computational simulations to compare the models under ecologically relevant circumstances. The simulations show that the results predicted by both models are inconsistent with those observed in real animals, and they propose that the brain must use the full pattern of neural responses to calculate the location of a sound. One of the parts of the brain that is responsible for locating sounds is the inferior colliculus. Studies in cats and humans have shown that damage to the inferior colliculus on one side of the brain prevents accurate localization of sounds on the opposite side of the body, but the animals are still able to locate sounds on the same side. This finding is difficult to explain using the hemispheric model, but Goodman et al. show that it can be explained with pattern-based models. DOI: http://dx.doi.org/10.7554/eLife.01312.002