The Role of Auditory Cortex in Speech Motor Control

当我们说话的时候，我们如何听到自己的声音？理解言语感知如何与言语产生相互作用是一个长期存在的问题，经典的研究是通过观察改变听觉反馈如何影响言语来进行的。然而，最近，功能性神经影像学方法的出现为这个问题提供了一种新的方法：研究语音产生如何影响听觉感知的神经过程。一些研究表明，说话的行为抑制了听觉皮层和相关区域对语音的正常反应。约翰·F博士的研究。Houde认为，这种抑制反映了实际听觉输入和对该听觉输入的预测之间的比较。在这些初步研究的基础上，Houde博士及其同事开发了一个模型，该模型来自现代控制理论，用于研究语音产生过程中听觉反馈是如何处理的。在NSF的支持下，Houde博士正在通过使用全头磁源成像（MSI）来监测听觉皮层的活动来测试这个模型，因为说话者会对听觉反馈的短暂扰动做出反应。先前的研究表明，这种言语扰动会导致言语运动输出的补偿反应。在这个项目中，研究人员首先确定听觉皮层是否是调节这些补偿反应的神经回路的一部分，通过研究说话者的扰动反应的变化如何与听觉皮层的活动相关。他们的下一步是确定他们的反馈处理模型是否解释了先前在听觉皮层中观察到的反应。该模型的一个关键概念是听觉反馈不直接影响言语运动输出。相反，输入反馈与内部生成的预期反馈的预测进行比较，得到的反馈预测误差用于控制语音输出。该研究测试了听觉皮层对反馈扰动的反应是否与该模型一致。该项目不仅对理解连接语音感知和产生的神经回路很重要。该项目涉及使用最先进的MSI方法来测试语音反馈处理的工程控制理论模型的预测。研究团队接受了语音研究，工程控制理论，信号处理，神经科学和磁源成像方法的培训。该项目将使参与的学生和博士后获得功能性神经成像的经验，并了解控制理论概念-这是一个对理解运动控制很重要的知识领域，但通常在神经科学，生物工程和认知科学学生的教育中被忽视。虽然这项研究的重点是言语运动控制，但它的研究强调了研究知觉与产生的重要性，以了解运动控制和运动功能障碍的一般问题。

How do we hear ourselves while we're speaking? Understanding how speech perception interacts with speech production is a longstanding issue that has classically been investigated by looking at how altering auditory feedback affects speech. Recently, however, the advent of functional neuroimaging methods has allowed a new approach to the issue: examining how producing speech affects the neural processes serving auditory perception. Several studies have shown that the act of speaking suppresses the normal response to speech sounds in auditory cortex and associated regions. Previous studies by Dr. John F. Houde suggest that this suppression reflects a comparison between actual auditory input and a prediction of that auditory input. Based on these initial studies, Dr. Houde and colleagues developed a model, derived from modern control theory, for how auditory feedback is processed during speech production. With support of NSF, Dr. Houde is testing this model by using whole-head magnetic source imaging (MSI) to monitor activity in auditory cortex as speakers respond to brief perturbations of their auditory feedback. Prior studies have shown that such speech perturbations cause compensatory responses in speech motor output. In this project, researchers are first determining whether auditory cortex is part of the neural circuitry mediating these compensatory responses by examining how variations in speaker's perturbation responses are correlated with activity in auditory cortex. Their next step is determining if their model of feedback processing explains the responses previously observed in auditory cortex. A key concept of the model is that auditory feedback does not directly affect speech motor output. Instead, incoming feedback is compared with an internally-generated prediction of the expected feedback, with the resulting feedback prediction error used to control speech output. The research tests whether the responses of auditory cortex to feedback perturbations are consistent with this model.This project is important not only for understanding the neural circuits linking speech perception and production. This project involves using state-of-the art MSI methods to test predictions of an engineering control theory model of speech feedback processing. The research team is trained in the speech research, engineering control theory, signal processing, neuroscience and magnetic source imaging methods needed to conduct this research. The project will enable students and postdocs involved to gain experience in functional neuroimaging as well as learn about control theory concepts - an area of knowledge important for understanding motor control but usually neglected in the education of neuroscience, bioengineering and cognitive science students. And although this research is focused on speech motor control, its research emphasizes the importance of studying perception in conjunction with production to understand general problems in motor control and motor dysfunctions.