Development of Auditory Response Selectivity

描述（由申请人提供）：这是一份在下丘和听觉皮层水平上继续研究哺乳动物听觉系统中物种典型发声处理的神经回路的个体发生的提案。对人类语言习得和鸟类鸣叫学习的研究表明，遗传指令引导人们注意与行为相关的发声，而关键时期的经验对于成熟是必要的。在这个敏感时期，适当的光谱时间过滤器的发展被认为是感知和发声的正常成熟的关键。在之前的资助期间，研究人员利用苍白蝙蝠的听觉系统记录了回声定位脉冲的神经元选择性发展的时间过程，回声定位脉冲是许多物种（包括人类语言）发声中常见的调频扫描。这些研究还揭示了形成这种选择性的一些抑制机制。他们还表明，听觉皮层并不是简单地继承了反应选择性，而是进一步调节了这种选择性。Aim 1的研究结果表明，与回声定位的成年蝙蝠一起长大的静音蝙蝠幼崽没有正常发育，这表明幼崽必须主动产生回声定位脉冲才能发育出与成年蝙蝠相似的神经元选择性。目的2将利用gaba能受体的阻断来揭示在发育过程中在丘和皮层水平上的抑制的本质。Aim 3扩展了这一发现，即在发育过程中，缺乏成人样抑制反应特性的神经元仍然可以表达由促进机制形成的反应选择性。我们将对这些机制进行研究。目的4将发展成熟的神经解剖学措施。淡色蝙蝠听觉系统的丘脑皮质突起是不寻常的；服务于回声定位和被动听觉的通路通过内侧膝状体的不同分支。在个体发育过程中，两个丘脑皮质通路重叠。我们将研究路径分离的时间过程。总之，苍白蝙蝠听觉系统的明显生理和解剖特化提供了一个机会，可以广泛地解决经验在影响哺乳动物听觉系统中服务于交流的神经回路成熟中的作用。

DESCRIPTION (provided by applicant): This is a proposal to continue examination of the ontogeny of the neural circuitry underlying the processing of species-typical vocalizations in the mammalian auditory system, at the levels of the inferior colliculus and auditory cortex. Studies of language acquisition in humans and song learning in birds show that genetic instruction directs attention to behaviorally relevant vocalizations, while experience during a critical period is necessary for maturation. During this sensitive period, the development of appropriate spectrotemporal filters is thought to be crucial for normal maturation of the perception and production of vocalizations. During the previous grant period, the pallid bat auditory system was used to document the time course of the development of neuronal selectivity for the echolocation pulse, an FM sweep common in the vocalizations of many species, including human language. These studies also revealed some of the inhibitory mechanisms that shape this selectivity. They also show that auditory cortex, rather than simply inheriting response selectivity, further tunes this selectivity. Aim 1 addresses the finding that muted bat pups raised with echolocating adults did not develop normally, suggesting that pups must actively produce echolocation pulses to develop adult-like neuronal selectivity. Aim 2 will use the blockade of GABAergic receptors to reveal the nature of the inhibition laid down during development at both the collicular and cortical levels. Aim 3 extends the finding that, during development, neurons lacking adult-like inhibitory response properties can nonetheless express response selectivity shaped by facilitatory mechanisms. These mechanisms will be examined. Aim 4 will develop neuroanatomical measures of maturation. The thalamocortical projections of the pallid bat auditory system are unusual; the pathways serving echolocation and passive hearing are routed through different subdivisions of the medial geniculate body. During ontogeny, the two thalamocortical pathways overlap. The time course for pathway segregation will be examined. In summary, the pronounced physiological and anatomical specializations of the pallid bat auditory system offer an opportunity to broadly address the role of experience in influencing the maturation of the neural circuitry serving communication in the mammalian auditory system.