Cortical Plasticity and Processing of Speech Sounds

描述(由申请人提供)：在美国，大约每15名进入小学的儿童中就有一人患有严重的发育性语言障碍，原因不明。对言语声学的详细研究极大地改善了对语言障碍的理解和治疗。这些研究也为研究语音的神经表征提供了必要的基础。虽然外周表征已被广泛研究，但对参与语音处理的大脑皮层机制知之甚少。这一建议的目的是定义哺乳动物听觉皮质神经元对人类语音的分布反应，并确定在语音的神经表征中可能存在哪些经验依赖性的变化。该项目的第一个目标将是准确地记录听觉皮质神经元对语音的分布式反应。我们的初步结果(来自两个不同听觉区域的清醒和麻醉录音)表明，频率带宽和前向掩蔽时间过程似乎解释了大多数听觉皮质神经元的言语反应。第二个目标将是记录对夸张的语音的分布式皮质反应，这种声音已被用于治疗数千名儿童的语言学习障碍。我们的初步发现表明，修改后的语音产生的大脑皮质活动模式比自然语音产生的模式更明显。第三个目标将是确定大脑皮质神经元是如何通过暴露于自然和修改的语音中而改变的。拟议的研究结果将增加我们对人类听觉皮质中可能有助于语音处理和学习的神经机制的理解。这些研究得出的见解将影响语言障碍的行为和感觉康复的使用和发展。

DESCRIPTION (provided by applicant): Approximately one out of every fifteen children entering elementary school in the U.S. has a significant developmental language impairment of unknown origin. Detailed studies of speech acoustics have significantly improved understanding and treatment of language impairments. These studies also provide the foundation needed to investigate the neural representation of speech. While peripheral representations have been extensively studied, relatively little is known about the cortical mechanisms that contribute to speech processing. The objective of this proposal is to define the distributed response of mammalian auditory cortex neurons to human speech sounds and to determine what experience-dependent changes in the neural representation of speech are possible. The first aim of the project will be to precisely document the distributed response of auditory cortex neurons to speech sounds. Our preliminary results (from awake and anesthetized recordings in two distinct auditory fields) indicate that frequency bandwidth and forward masking time course appear to account for speech responses of most auditory cortex neurons. The second aim will be to document the distributed cortical response to exaggerated speech sounds that have been used to treat language-learning impairments in thousands of children. Our initial findings indicate that the cortical activity patterns generated by modified speech are more distinct than the patterns generated by natural speech sounds. The third aim will be to establish how cortical neurons are modified by exposure to natural and modified speech sounds. The results of the proposed studies will add to our understanding of neural mechanisms that could contribute to speech processing and learning in human auditory cortex. Insights derived from these studies will influence the use and development of behavioral and sensory rehabilitation of language impairments.