Online modulation of auditory brainstem responses to speech

描述(申请人提供)：这个项目的目标是使用多模式(功能磁共振成像(FMRI)和脑电(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的性质。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，最近的研究表明信号的主动转换，如听觉中脑和脑干所代表的。然而，这种早期感觉可塑性背后的机制尚不清楚。在这个方案中，提出了一个皮质下听觉可塑性的综合模型(预测性调谐)，该模型主张通过皮质分离通路对自下而上的信号进行连续的、在线的调制，基于一种不断预测传入刺激规则的算法，从而改变听觉通路中的表征。这项建议利用跨语言和病例对照设计以及创新的脑电方法，直接解决脑干电路在语音动态编码中的作用，并测试相互竞争的神经模型(本地调制与预测调谐)。语音处理过程中的因果影响(自上而下与自下而上)将使用功能磁共振有效连接性分析进行测试。拟议中的实验将提供脑干可塑性潜在机制的全面检查，并扩大对言语感知神经生物学的理解，使其超越目前的皮质中心焦点。最近的研究表明，许多临床人群在脑干水平上表现出语音编码缺陷。本建议中开发的设计和分析方法可用于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.