Neural Encoding and Connectivity in human speech perception

描述（由申请人提供）：定义支持言语和语言功能的基本神经机制是对失语症或阅读障碍等沟通障碍的临床见解的根本挑战。更好地理解言语的神经基础也可能导致神经假体装置的开发，用于使影响交流能力的神经障碍（例如，ALS或中风）。为了实现这些目标，必须应对两个关键挑战。首先，皮质活动是如何表征语音的？尽管说话者和环境条件存在很大差异，但人类仍然能够流畅地理解语音，但支持这种不变识别能力的潜在神经表征从根本上是未知的。第二，皮层言语表征的解剖学基础是什么？理论模型和非人类动物的数据表明，听觉对象识别可能是分层组织的，但这种架构是否存在于人类大脑中仍然是未知的。该项目将集中在这两个关键问题，神经表征和连接，通过调查颅内（皮层电图，ECoG）的反应，以言语测量微电极阵列在神经外科患者。在指导K99阶段，第一个具体目标将使用神经编码模型方法研究高阶听觉皮层中语音的神经表征。神经编码模型定量地描述了特定脑区编码的语音特征，并预测了对新语音刺激的神经反应。将通过比较语音模型来测试分类语音语音表示的存在，语音模型表示语音级别类别之间的声学不变性，基于语音频谱图的线性频谱时间模型。在独立的R00阶段，第二个具体目标将使用皮层电刺激（ECS）和功能连接分析来研究支持语音感知的神经回路的连接性。ECS直接映射受刺激的大脑部位的解剖连接，而功能连接分析则确定这些部位是如何连接的。 连接在言语感知期间被调制。比较的连接图的特征选择性的拟合编码模型（目标1）将提供一个全面的看法，在高阶听觉皮层的语音表示的功能组织。理解人类皮层中语音识别的表示和连接对于许多健康应用具有重要意义。精确的编码模型可以用来从神经活动中解码语音，并形成用于通信的假肢设备的基础。此外，映射语音的功能组织将允许在神经外科手术过程中更精确地确定关键的语音部位，并将提供对失语症和发育性阅读障碍等沟通障碍的关键脑区和回路的见解。

DESCRIPTION (provided by applicant): Defining the basic neural mechanisms supporting speech and language function is a fundamental challenge for clinical insights into communication disorders such as aphasia or dyslexia. Better understanding of the neural basis of speech may also lead to development of neural prosthetic devices for disabling neurological disorders affecting communication ability (e.g., ALS or stroke). To achieve these goals, two key challenges must be addressed. First, how is speech sounds represented by cortical activity? Humans fluidly understand speech despite large variations in speakers and environmental conditions, but the underlying neural representations that support this invariant recognition ability are fundamentally unknown. Second, what is the anatomical substrate of cortical speech representation? Theoretical models and nonhuman animal data suggest auditory object recognition may be organized hierarchically, but it remains unknown if this architecture is present in the human brain. This project will focus on these two key questions, neural representation and connectivity, by investigating intracranial (electrocorticographic, ECoG) responses to speech measured with microelectrode arrays in neurosurgical patients. During the mentored K99 phase, the first specific aim will investigate the neural representation of speech in higher order auditory cortex using a neural encoding model approach. A neural encoding model describes quantitatively what speech features are encoded by specific brain areas and predicts the neural response to novel speech stimuli. The presence of a categorical phonetic speech representation will be tested by comparing a phonetic model, which represents acoustic invariance among phone-level categories, to a linear spectrotemporal model based on the speech spectrogram. During the independent R00 phase, the second specific aim will investigate the connectivity of neural circuits supporting speech perception using electrical cortical stimulation (ECS) and functional connectivity analysis. ECS directly maps anatomical connectivity of stimulated brain sites, while functional connectivity analysis identifies how these connections are modulated during speech perception. Comparison of the connectivity maps to the feature selectivity of fitted encoding models (Aim 1) will provide a comprehensive view of the functional organization of speech representation in higher order auditory cortex. Understanding the representation and connectivity of speech recognition in human cortex has significant implications for a number of health applications. Accurate encoding models can be used to decode speech from neural activity and form the basis of prosthetic devices for communication. Furthermore, mapping the functional organization of speech will allow more precise determination of critical speech sites during neurosurgical procedures and will provide insights into key brain areas and circuits underlying communication disorders such as aphasia and developmental dyslexia.