Neural coding of echo-envelope disparities in echolocating bats
Neural coding of echo-envelope disparities in echolocating bats
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DOI：
10.1007/s00359-010-0571-z
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发表时间：
2011-05-01
影响因子：
2.1
通讯作者：
Wiegrebe, Lutz
中科院分区：
文献类型：
--
作者：
Borina, Frank;Firzlaff, Uwe;Wiegrebe, Lutz
回声定位的有效使用不仅需要测量发出的呼叫和返回的回声之间的延迟来估计声穿透物体的距离。为了在方位角和仰角上定位物体，蝙蝠的听觉系统必须根据它们的双耳特性来分析返回的回声，即，回声的耳间强度差和时间差（IID和ITD）。IID用于回声定位的有效性是无可争议的，但是当蝙蝠声穿透复杂物体时，回声的时间结构可以促进在包络ITD方面的回声包络的分析。使用细胞外记录从听觉中脑的蝙蝠，Phyllostomus变色，我们发现了一个人口的神经元，是敏感的信封ITDs的回声，他们的声纳呼叫。此外，随着回波包络时间波动的增加，包络ITD灵敏度得到提高，回波包络是一个与植被等复杂自然反射体的空间统计相关的声纳参数。数据表明，在蝙蝠信封ITDs不仅可以用来定位外部，猎物产生的声音，但也在回声定位的上下文中。具体而言，在回声包络的时间波动，这是创建时，声纳发射是从一个复杂的自然目标反射，支持ITD介导的回声定位。
The effective use of echolocation requires not only measuring the delay between the emitted call and returning echo to estimate the distance of an ensonified object. To locate an object in azimuth and elevation, the bat's auditory system must analyze the returning echoes in terms of their binaural properties, i.e., the echoes' interaural intensity and time differences (IIDs and ITDs). The effectiveness of IIDs for echolocation is undisputed, but when bats ensonify complex objects, the temporal structure of echoes may facilitate the analysis of the echo envelope in terms of envelope ITDs. Using extracellular recordings from the auditory midbrain of the bat, Phyllostomus discolor, we found a population of neurons that are sensitive to envelope ITDs of echoes of their sonar calls. Moreover, the envelope-ITD sensitivity improved with increasing temporal fluctuations in the echo envelopes, a sonar parameter related to the spatial statistics of complex natural reflectors like vegetation. The data show that in bats envelope ITDs may be used not only to locate external, prey-generated rustling sounds but also in the context of echolocation. Specifically, the temporal fluctuations in the echo envelope, which are created when the sonar emission is reflected from a complex natural target, support ITD-mediated echolocation.