Online modulation of auditory brainstem responses to speech

描述（由申请人提供）：本项目的目标是使用多模态（功能磁共振成像（fMRI）和脑电图（EEG））神经成像方法来检查语言和非语言对成人语音信号脑干编码的影响。与听觉脑干核团作为行为相关信号的被动中继站的概念直接冲突，最近的研究已经证明了信号的主动转化，如听觉中脑和脑干所示。然而，这种早期感觉可塑性的机制尚不清楚。在这个建议中，一个整合模型的皮层下听觉可塑性的假设（预测调谐），主张通过离皮质通路的自下而上的信号的连续，在线调制，基于一个算法，不断预期传入的刺激信号，从而改变表示在听觉通路。该提案利用跨语言和病例对照设计以及创新的EEG方法来直接解决脑干电路在语音动态编码中的作用，并测试竞争神经模型（局部调制与预测调谐）。语音处理过程中的因果影响（自上而下与自下而上）将使用fMRI有效连接分析进行测试。拟议中的实验将提供一个全面的检查机制的脑干可塑性和扩展的理解的神经生物学的语音感知超越目前的皮质中枢集中。最近的研究表明，许多临床人群表现出脑干水平的语音编码缺陷。在这个提议中开发的设计和分析方法可以用来评估这种编码缺陷的轨迹（自下而上与自上而下）。

DESCRIPTION (provided by applicant): The goal of this project is to use multimodal (functional magnetic resonance imaging (fMRI) and electroencephalography (EEG)) neuroimaging methods to examine the nature of linguistic and non-linguistic influences on brainstem encoding of speech signals in adults. In direct conflict with the concept of auditory brainstem nuclei as passive relay stations for behaviorally-relevant signals, recent studies have demonstrated active transformation of the signal, as represented in the auditory midbrain and brainstem. However, the mechanisms underlying such early sensory plasticity are unclear. In this proposal, an integrative model of subcortical auditory plasticity is posited (predictive tunin), which argues for a continuous, online modulation of bottom-up signals via corticofugal pathways, based on an algorithm that constantly anticipates incoming stimulus regularities, thereby transforming representation in the auditory pathway. This proposal utilizes cross-language and case-control designs and innovative EEG methods to directly address the role of brainstem circuitry in dynamic encoding of speech and test competing neural models (local modulation vs. predictive tuning). Causal influences (top-down vs. bottom-up) during speech processing will be tested using fMRI effective connectivity analyses. The proposed experiments will provide a comprehensive examination of mechanisms underlying brainstem plasticity and expand the understanding of the neurobiology of speech perception beyond the current corticocentric focus. Recent studies show that a number of clinical populations exhibit speech-encoding deficits at the level of the brainstem. The design and analysis methods developed in this proposal can be used to evaluate the locus (bottom-up versus top-down) of such encoding deficits.