Delay-tuned neurons in the inferior colliculus of the mustached bat: Implications for analyses of target distance
Delay-tuned neurons in the inferior colliculus of the mustached bat: Implications for analyses of target distance
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DOI：
10.1152/jn.1999.82.3.1326
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发表时间：
1999-09-01
影响因子：
2.5
通讯作者：
Wenstrup, JJ
中科院分区：
文献类型：
--
作者：
Portfors, CV;Wenstrup, JJ
我们研究了小胡子蝙蝠下丘中央核（ICC）延迟调谐神经元的反应特性。在小胡子蝙蝠中，延迟调谐神经元对发射脉冲中的一谐波调频（FM1）扫描和返回回波中的高谐波调频（FM2， FM3或FM4）分量的组合反应最好，被称为FM-FM神经元。我们还检测了H1-CF2神经元。H1-CF2神经元对发射脉冲中的第一谐波（HI）和返回回波中的第二恒频（CF2）分量的同时呈现做出反应。这些神经元可以作为比较，因为它们被认为编码声纳目标的不同特征，而不是FM-FM神经元。只有7%的神经元（14/198）表现出单一的兴奋性调谐曲线。其余的神经元（184个）对两个不同频段的声音表现出复杂的反应。大多数神经元（51%,101）是由小胡子蝙蝠发声中特定成分的组合促进的。百分之二十表现出纯粹的抑制性相互作用。其余的神经元对两个不同的频率做出反应，没有任何促进或抑制作用。在高频信号适当延迟的情况下，FM-FM神经元（69）受到模拟脉冲中的FM1分量和模拟回波中的高谐波FM分量的促进。FM-FM神经元产生最大促进的延迟（“最佳延迟”）范围在0 - 20 ms之间，对应于小于或等于3.4 m的目标距离，50%延迟宽度在2 - 13 ms之间，FM-FM神经元之间延迟调节的清晰度不同。平均而言，FM-FM神经元的促进反应比单独对两种信号的反应总和大104%。通过比较延迟调谐的前视皮层神经元和内膝状体神经元的响应特性，我们发现前视皮层和后视皮层的最佳延迟范围、延迟调谐的锐度和促进强度是相似的。这表明，在TC水平上，FM-FM神经元的基本反应特性已经建立，并且它们不会随着听觉加工的上升而发生广泛的转换。
We examined response properties of delay-tuned neurons in the central nucleus of the inferior colliculus (ICC) of the mustached bat. In the mustached bat, delay-tuned neurons respond best to the combination of the first-harmonic, Frequency-modulated (FM1) sweep in the emitted pulse and a higher harmonic frequency-modulated (FM2, FM3 or FM4) component in returning echoes and are referred to as FM-FM neurons. We also examined H1-CF2 neurons. H1-CF2 neurons responded to simultaneous presentation of the first harmonic (HI) in the emitted pulse and the second constant frequency (CF2) component in returning echoes. These neurons served as a comparison as they are thought to encode different features of sonar targets than FM-FM neurons. Only 7% of our neurons (14/198) displayed a single excitatory tuning curve. The rest of the neurons (184) displayed complex responses to sounds in two separate frequency bands. The majority (51%, 101) of neurons were facilitated by the combination of specific components in the mustached bat's vocalizations. Twenty-live percent showed purely inhibitory interactions. The remaining neurons responded to two separate frequencies, without any facilitation or inhibition. FM-FM neurons (69) were facilitated by the FM1 component in the simulated pulse and a higher harmonic FM component in simulated echoes, provided the high-frequency signal was delayed the appropriate amount. The delay producing maximal facilitation ("best delay") among FM-FM neurons ranged between 0 and 20 ms, corresponding to target distances less than or equal to 3.4 m Sharpness of delay tuning varied among FM-FM neurons with 50% delay widths between 2 and 13 ms. On average, the facilitated responses of FM-FM neurons were 104% greater than the sum of the responses to the two signals alone. In comparing response properties of delay-tuned, FM-FM neurons in the ICC with those in the medial geniculate body (MGB) from other studies, we find that the range of best delays, sharpness of delay tuning and strength of facilitation are similar in the ICC and MGB. This suggests that by the level of the TC, the basic response properties of FM-FM neurons are established, and they do not undergo extensive transformations with ascending auditory processing.