Neurophysiological Basis of Speech Perception

描述（由申请人提供）：本项目的长期目标是识别语言感知的神经生理过程。语音的一个定义特征是它们被分类地感知。也就是说，不同的声学刺激倾向于被分组到感知类别中，从而导致跨类别边界的区分比类别边界内的区分更好。我们的主要假设是，左半球对语音处理的优势程度与它们的分类感知有关，而不是与语音的任何特殊地位有关。我们假设，左半球是专门为分类知觉的声音，语音和非语音，而右半球是专门为连续的歧视的声音。功能性磁共振成像（fMRI）和事件相关电位（ERP）技术将用于实现五个特定的目标：（1）识别大脑区域的分类和连续感知的语音和类语音的声音。我们预测，分类知觉将与听觉匹配，但持续感知的声音的感知过程中没有激活的左侧听觉皮层区域的神经激活。(2)定义声音的分类知觉和相关的大脑半球偏侧化模式之间的关系。我们预测，分类感知将导致更大的神经激活的单侧化比连续感知声学匹配的声音。(3)通过训练，定义大脑从分类感知到连续感知以及从连续感知到分类感知的可塑性背后的神经过程。我们预测，学习和遗忘的知觉类别将导致半球转移的处理和相关的激活的神经基板的类别表征。(4)通过比较在前注意和主动目标检测条件下的古怪辨别过程中的大脑激活模式，测试注意对分类感知的影响。(5)探索涉及分类和连续感知的大脑区域激活的时间过程，基于每种感知类型的神经发生器的fMRI约束偶极模型。言语感知在人类认知中起着基础性的作用。了解言语分类知觉的神经生理学基础及其与大脑半球偏侧化的关系，可能有助于改善对阅读障碍、特定语言障碍和精神分裂症等疾病的治疗，并有助于改善单侧颞叶疾病（如中风和颞叶癫痫）的康复方法。

DESCRIPTION (provided by applicant): The tong-term objective of this project is to identify the neurophysiological processes underlying speech perception. A defining characteristic of speech sounds is that they are perceived categorically. That is, different acoustic stimuli tend to be grouped into perceptual categories, resulting in better discrimination across than within category boundaries. Our main hypothesis is that the degree of left hemispheric dominance for processing of speech sounds is related to their categorical perception rather than to any special status as speech sounds. We hypothesize that the left hemisphere is specialized for categorical perception of sounds, both speech and nonspeech, whereas the right hemisphere is specialized for continuous discrimination of sounds. Functional magnetic resonance imaging (fMRI) and event-related potential (ERP) techniques will be used to achieve five specific aims: (1) Identify brain areas underlying categorical and continuous perception of speech and speech-like sounds. We predict that categorical perception will be associated with neural activation in regions of the left auditory cortex not activated during perception of acoustically matched but continuously-perceived sounds. (2) Define the relation between categorical perception of sounds and associated patterns of hemispheric lateralization. We predict that categorical perception will result in greater leftward lateralization of neural activation than continuous perception of acoustically matched sounds. (3) Define the neural processes underlying plasticity of the brain in shifting from categorical to continuous perception and from continuous to categorical perception, through training. We predict that the learning and unlearning of perceptual categories will induce hemispheric shifts in processing and associated activation of neural substrates for category representations. (4) Test the effects of attention on categorical perception by comparing brain activation patterns during oddball discrimination under pre-attentive and under active target detection conditions. (5) Explore the temporal course of activation of brain areas involved in categorical and continuous perception, based on fMRI-constrained dipole modeling of the neural generators underlying each type of perception. Speech perception plays a fundamental role in human cognition. Understanding the neurophysiological basis of categorical perception of speech and its relation to hemispheric lateralization may suggest means of improving the treatment of disorders such as dyslexia, specific language impairment and schizophrenia, and means of improving rehabilitation methods in diseases affecting the temporal lobe unilaterally, such as stroke and temporal lobe epilepsy.