Neurophysiological Basis of Speech Perception

描述(由申请者提供)：本项目的长期目标是确定潜在的言语感知的神经生理过程。语音的一个决定性特征是它们可以被明确地感知。也就是说，不同的声音刺激往往被分成感知类别，导致跨类别的区分比类别内的区分更好。我们的主要假设是，左半球对语音加工的优势程度与他们的范畴知觉有关，而不是与语音的任何特殊地位有关。我们假设，左脑专门负责语音和非语音的分类感知，而右脑则专门负责连续的声音辨别。功能磁共振成像(FMRI)和事件相关电位(ERP)技术将用于实现五个具体目标：(1)识别对语音和类似语音的分类和连续感知的大脑区域。我们预测，类别知觉将与左侧听觉皮质区域的神经激活有关，这些区域在感知声学匹配但持续感知的声音时并未激活。(2)界定声音的范畴知觉与大脑半球偏侧化相关模式之间的关系。我们预测，与连续感知声学匹配的声音相比，范畴感知将导致神经激活的更大的左侧化。(3)通过训练，定义大脑在从范畴知觉到连续知觉和从连续知觉到范畴知觉转变过程中的神经可塑性。我们预测，知觉类别的学习和遗忘将导致加工和相关激活的神经底物的半球转移，用于类别表征。(4)通过比较注意前和主动目标探测条件下古怪辨别时的脑激活模式，检验注意对范畴知觉的影响。(5)基于fMRI对每种类型知觉背后的神经生成器的限制偶极子模型，探索涉及分类知觉和连续知觉的脑区激活的时间过程。言语感知在人类认知中起着基础性的作用。了解言语范畴知觉的神经生理学基础及其与大脑半球偏侧化的关系，可能会为改善阅读障碍、特殊语言障碍和精神分裂症等障碍的治疗方法，以及改善中风和颞叶癫痫等单方面影响颞叶的疾病的康复方法提供建议。

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.