Bilateral integration of the auditory scene

摘要 听觉系统需要回答一个具有挑战性的问题：到达每只耳朵的声音是否源自 来自单一来源还是多个来源？为了完成这一感知壮举，中枢听觉神经回路 必须准确评估双边声音信号的频谱和时间轮廓，以绑定和整合相关的 声学对象。这种双边整合过程的失败可以解释许多感知和 伴随听觉障碍的行为障碍，例如耳鸣、老年性耳聋和中枢听觉 大多数人在一生中都会经历处理障碍。令人惊讶的是，神经 实现声学信息双边整合的机制在很大程度上仍然未知，但很可能 依赖于连接听觉两半部分的兴奋性和抑制性连接的复杂平衡 大脑。尽管听觉脑干中心已对连合通路进行了深入研究，但人们对其知之甚少 关于听觉大脑高级中心连合电路的功能组织。因此，长 我们研究的长期目标是了解连合通路的功能组织 双侧听觉信息的处理。我们的主要目标是测试一个很大程度上被忽视但尚未解决的问题 实质性的连合听觉投射系统，即从下丘到下丘的通路 对侧内侧膝状体。我们的中心假设是内侧膝状体整合 来自同侧和对侧下丘的输入在功能和地形上均一致 类型特定级别。此外，我们假设这种双侧顶盖丘脑会聚的破坏 导致内侧膝状体中声学信息的频谱和时间处理缺陷， 这会导致中枢听觉系统紊乱。我们将通过评估来检验我们的假设：1） 功能性神经解剖学和 2) 这些对侧顶盖丘脑通路对神经生理学的影响 听觉处理，通过采用现代的、细胞类型特异性的神经解剖学和神经生理学 接近。因此，这些研究具有创新性，因为它们解决了未知和未经探索的功能 对侧听觉顶丘脑通路的组织。最后，提出的实验是 意义重大，因为它们有望揭示听觉处理的机械特征，这将产生积极的影响 对中枢听觉障碍的神经诊断和治疗的影响。

ABSTRACT The auditory system is posed with answering a challenging question: Does sound arriving at each ear originate from a single source or multiple sources? To accomplish this perceptual feat, central auditory neural circuits must accurately assess the spectral and temporal profile of bilateral sound signals to bind and integrate related acoustic objects. Failure of this bilateral integrative process can account for many of the perceptual and behavioral impairments that accompany auditory disorders, such as tinnitus, presbycusis and central auditory processing disorders, which most of the population will experience over the lifespan. Surprisingly, the neural mechanisms that enable this bilateral integration of acoustic information remain largely unknown, but likely depend on an intricate balance of excitatory and inhibitory connections that link the two halves of the auditory brain. Although commissural pathways have been well studied in auditory brainstem centers, much less is known about the functional organization of commissural circuitry in higher centers of the auditory brain. Thus, the long- term goals of our research are to understand the functional organization of the commissural pathways in the processing of bilateral auditory information. Our primary objective here is to test a largely overlooked, yet substantial, commissural auditory projection system, i.e. the pathway from the inferior colliculus to the contralateral medial geniculate body. Our central hypothesis is that the medial geniculate body integrates functionally and topographically aligned inputs from both the ipsilateral and contralateral inferior colliculi at a cell- type specific level. Further, we hypothesize that the disruption of such bilateral tectothalamic convergence results in deficits to the spectral and temporal processing of acoustic information in the medial geniculate body, which contributes to disorders of the central auditory system. We will test our hypotheses by assessing: 1) the functional neuroanatomy and 2) the neurophysiological impact of these contralateral tectothalamic pathways on auditory processing, by employing modern, cell-type specific neuroanatomical and neurophysiological approaches. As such, these studies are innovative since they address the unknown and unexplored functional organization of the contralateral auditory tectothalamic pathways. Finally, the proposed experiments are significant since they are expected to reveal mechanistic features of auditory processing that will have a positive impact for neural diagnostics and treatments for central auditory impairments.