Development of Auditory Response Selectivity

描述(由申请人提供)：这是一项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个体发育的建议，在下丘和听觉皮质水平。对人类语言习得和鸟类歌唱学习的研究表明，遗传指令将注意力引导到与行为相关的发声上，而关键时期的经验是成熟所必需的。在这个敏感的时期，适当的频域滤光器的发展被认为是发声知觉和发声的正常成熟的关键。在之前的赠款期间，苍白的蝙蝠听觉系统被用来记录神经元对回声定位脉冲的选择性发展的时间进程，回声定位脉冲是一种FM扫描，在包括人类语言在内的许多物种的发声中很常见。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，听觉皮质不是简单地继承反应选择性，而是进一步调整这种选择性。目的1解决与回声定位成虫一起长大的沉默蝙蝠幼崽不能正常发育的发现，这表明幼崽必须主动产生回声定位脉冲来发展成体样神经元的选择性。目标2将使用GABA能受体的阻断来揭示在发育过程中在皮质和皮质水平上所产生的抑制的本质。目标3扩展了这一发现，即在发育过程中，缺乏成体样抑制反应特性的神经元仍然可以表达由易化机制形成的反应选择性。我们将研究这些机制。目标4将开发成熟的神经解剖学测量方法。苍白蝙蝠听觉系统的丘脑皮质投射是不寻常的；为回声定位和被动听力服务的通路通过内侧膝状体的不同细分进行传递。在个体发育过程中，两条丘脑皮质通路重叠。将研究通道分离的时间进程。总之，苍白蝙蝠听觉系统明显的生理和解剖学特化提供了一个机会，可以广泛地研究经验在影响哺乳动物听觉系统中用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.