Development of Auditory Response Selectivity

描述（由申请人提供）：这是一项在下丘和听觉皮层水平继续检查哺乳动物听觉系统中处理物种典型发声的神经回路个体发育的建议。对人类语言习得和鸟类歌曲学习的研究表明，遗传指令将注意力引导到与行为相关的发声，而关键时期的经验是成熟所必需的。在这一敏感时期，适当的频谱时间滤波器的发展被认为是至关重要的感知和生产的发声的正常成熟。在上一个赠款期间，苍白的蝙蝠听觉系统被用来记录回声定位脉冲的神经元选择性发展的时间过程，这是一种在许多物种（包括人类语言）的发声中常见的FM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，而不是简单地继承反应的选择性，进一步调整这种选择性。目标1解决了这一发现，静音蝙蝠幼崽提出了回声定位的成年人没有正常发展，这表明幼崽必须积极产生回声定位脉冲，以发展成人一样的神经元选择性。目的2将使用GABA能受体的阻断来揭示在丘和皮层水平发育期间所形成的抑制的性质。目的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易化机制塑造的反应选择性。将对这些机制进行审查。目标4将发展成熟的神经解剖学测量。苍白的蝙蝠听觉系统的丘脑皮质投射是不寻常的;回声定位和被动听觉的途径是通过内侧膝状体的不同细分。在个体发育过程中，这两条丘脑皮质通路重叠。将检查通路分离的时间过程。总之，苍白的蝙蝠听觉系统的明显的生理和解剖专业化提供了一个机会，广泛地解决经验的作用，影响成熟的神经回路服务于哺乳动物听觉系统的通信。

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.