Bilateral integration of the auditory scene

摘要 听觉系统被用来回答一个具有挑战性的问题：到达每只耳朵的声音是否起源于 来自单一来源还是来自多个来源？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分布，以绑定和整合相关 声学物体。这一双边一体化进程的失败可以解释许多感知和 伴随听力障碍的行为障碍，如耳鸣、老年性耳聋和中枢性听力障碍 加工障碍，大多数人将在一生中经历这种疾病。令人惊讶的是，神经 实现这种双边声学信息整合的机制在很大程度上仍不清楚，但很可能 依赖于连接听觉两半的兴奋性和抑制性连接的复杂平衡 大脑。虽然在听觉脑干中心已经对连合通路进行了很好的研究，但知之甚少。 关于听觉大脑高级中枢的连合回路的功能组织。因此，长期的- 本研究的学期目标是了解大鼠脑内连合通路的功能组织。 双侧听觉信息的加工。我们在这里的主要目标是测试一个基本上被忽视的 实质的连合听觉投射系统，即从下丘到丘脑的通路。 对侧内侧膝状体。我们的中心假设是内侧膝状体整合了 同侧和对侧下丘在细胞的功能和地形上对齐的输入- 键入特定级别。此外，我们假设，这种双侧顶盖丘脑会聚的破坏 导致内侧膝状体对声音信息的频谱和时间处理的缺陷， 这会导致中枢听觉系统的紊乱。我们将通过评估以下各项来验证我们的假设：1) 功能神经解剖学和2)这些对侧顶盖丘脑通路对神经生理的影响 通过使用现代的、细胞类型的特定神经解剖学和神经生理学来进行听觉处理 接近了。因此，这些研究具有创新性，因为它们解决了未知和未探索的功能 对侧听觉顶盖丘脑通路的组织。最后，建议的实验是 意义重大，因为它们有望揭示听觉处理的机械特征，这将对 对中枢听觉损伤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.