Electrocorticographic Analysis of Phonological and Lexical Processing

描述（由申请人提供）：在语言感知和产生的基础上，皮层活动的时空动态还没有很好地描述。目前的神经成像技术，如功能磁共振成像和PET提供高空间分辨率，但缺乏足够的时间分辨率来解决语言的时间动态。相比之下，脑电图和脑磁图等电生理技术提供了高时间分辨率，但缺乏确定哪些皮层网络在语言感知和产生中起关键作用所需的空间分辨率。本研究旨在通过分析语言处理任务中获得的高时间分辨率和高空间分辨率的电信号来弥补这一文献空白。实验包括直接记录顽固性癫痫患者的皮质电活动（ECoG）。多个电极网格是神经外科放置在大脑表面提供广泛的覆盖左边缘语言皮质。高保真ECoG信号包含丰富的频谱信息。除了经典的事件相关电位（ERP）分析之外，时频分析技术提供了一个了解本地和全球网络连接的窗口。我们将使用最近描述的高伽马振荡响应（HG: 60-200 Hz）以及其他频段和erp作为神经活动的皮层标记。我们将采用两个任务，旨在阐明基本语音和词汇加工的时空动态。一项任务将包括听听觉呈现的音素，然后再现它们，而另一项任务将使用相同实验结构的单词。比较这两个任务将为确定涉及语音和词汇加工的皮层区域的时间动态提供基础。此外，我们将研究额下回（IFG）在接受加工中的作用。具体来说，我们将讨论IFG在语音加工中的有争议的作用。除了提供与语言理论相关的数据外，确定语言处理的时空动态可能会导致公共卫生方面的进步。新的脑成像技术可能允许在神经外科治疗几种疾病（如癫痫、肿瘤切除）时进行更短、更安全的手术，取代传统的皮质刺激成像，其相关的发病率与癫痫的诱发和成像过程的长度有关。

DESCRIPTION (provided by applicant): The spatiotemporal dynamics of cortical activity underlying speech perception and production are not well delineated. Current neuroimaging techniques such as fMRI and PET provide high spatial resolution but lack sufficient temporal resolution to address the temporal dynamics of language. In contrast, electrophysiological techniques such as EEG and MEG offer high temporal resolution but lack the spatial resolution needed to ascertain what cortical networks are critically involved in speech perception and production. This proposal aims to address this gap in the literature by analyzing electrical signals with both high temporal resolution and excellent spatial resolution acquired during language processing tasks. The experiments involve recording electrocorticogrpahic activity (ECoG) directly from the cortex of patients undergoing treatment for refractory epilepsy. Multiple electrode grids are neurosurgically placed on the surface of the brain providing extensive coverage of left perisylvian language cortices. The high fidelity ECoG signal contains a rich spectrum of information. In addition to classical event related potential (ERP) analysis, time- frequency analysis techniques offer a window into local and global network connectivity. We will use the recently described high gamma oscillatory response (HG: 60-200 Hz) together with other frequency bands and ERPs as cortical markers for neural activity. We will employ two tasks aimed at elucidating the spatiotemporal dynamics of basic phonological and lexical processing. One task will consist of hearing auditorily-presented phonemes and then re-producing them while the other will use words in the same experimental structure. Comparing the two tasks will serve as a basis for ascertaining the timing dynamics of cortical regions involved in phonological and lexical processing. Furthermore, we will examine the role of the inferior frontal gyrus (IFG) in receptive processing. Specifically, we will address the controversial role of IFG in phonological processing. In addition to providing data relevant to linguistic theory, determining the spatial and temporal dynamics of language processing may lead to advances in public health. New brain mapping techniques may permit shorter and safer procedures during neurosurgery for several disorders (i.e. epilepsy, tumor resection) replacing the traditional cortical stimulation mapping with its associated morbidity related to seizure induction and length of the mapping procedure. PUBLIC HEALTH RELEVANCE: This proposal will help create a cortical map of where and when different brain regions are active during comprehension and production of language. This will expand current theories of how the brain processes language as well provides new brain mapping techniques. Such mapping techniques may permit shorter and safer procedures during neurosurgery for several disorders (i.e. epilepsy, tumor resection) replacing the traditional cortical stimulation mapping with its associated morbidity related to seizure induction and length of the mapping procedure.