Basic and clinical investigation of speech processing mechanism for the improvement of cochlear implant

1)（1）内耳的语言加工（耳蜗电图）：正常人在元音和CV音节音的首端及元音的连续部分有CAPs，而CV音节的元音起始部分无CAPs。部分感音神经性耳聋患者缺乏这些CAP。我们证实了内耳产生的时间信息对语言感知的重要性，并开发了基于灵活时间窗放大的数字助听器。(2)口语的皮层加工机制（PET、MEG、MRI）：PET研究显示，正常人左右半球的听觉联合区主要处理对侧耳的语言输入，人工耳蜗植入者言语声激活听觉联合区，而噪声引起的rCBF仅在初级听觉区增加。在语前聋患者中，听觉联合区的激活缺失， ...更多信息 这表明，没有语音刺激，大脑皮层的语言网络是不发达的。利用脑磁图，我们发现正常人的听觉皮层被言语声激活的程度比被噪声激活的程度更高，从而证实了改变言语和噪声的皮层机制。我们还发现，在正常受试者的对侧半球的反应出现在潜伏期早于同侧的一个耳朵的声音输入。相反，在单侧耳聋患者中，没有观察到这种偏侧性。2）言语产生的皮层机制我们发现，正常成年人发出熟悉的语音时，听觉联想区没有对自己的声音进行监测，但当自己的声音听起来与发音的声音不同时，听觉言语反馈变得活跃。这些结果表明，大脑皮层存在完全的获得性言语输出机制，以及听觉言语反馈系统对发声和构音的纠正机制。在这项研究中，我们证实了辅助运动区的重要性，为编程的发音运动和小脑的调节发声。Wa还证明了大脑皮层对言语产生的加工过程是顺序的和平行的，这说明了大脑功能的合理性。少

1) Perception of language(1) processing of language in inner ear (Electrocochleography) : In normal subjects, CAPs were observed at the head of vowel and CV syllable sounds as well as at the continuous part of vowels, while CAPs were absent at the onset of vowel in CV syllable. These CAPs were lack in some sensorineural hearing loss patients. We confirmed the importance of temporal information made in inner ear for perception of language, and developed digital hearing aid based on amplification with flexible time window.(2) cortical processing mechnism for spoken language (PET,MEG,MRI) : PET studies showed that the auditory association areas in each hemisphere mainly processed language input from the contrlateral ear in normal subjects, and that speech sounds activated the auditory association areas while noise induced rCBF increase only in the primary auditory area in cochlear implant users. In prelingual deaf patiente, the activation of the auditory association areas was absent even … More with speech sounds stimulation, which indicated that the cortical network for language was not developed without speech sound stimuli. Using MEG, we found that the auditory cortices were more activated by speech sound than by noise in normal subjects, and confirmed the cortical mechanism to alter speech and noise. We also found that the response in the contralateral hemisphere appeared earlier in latency than that in the ipsilateral one to the ear where sounds were input in normal subjects. On the contrary, in unilateral deaf patients, this laterality was not observed. These results showed the reorganization of cortical network after unilateral hearing loss.2) cortical mechanisms for speech productionWe found that normal adult subjects vocalized familiar speech without monitoring their own voices in the auditory association areas, but that when the own voice sounded different to the articulated one, the auditory verbal feedback became active. These results indicate that there exist fully acquired speech output mechanism in cortex as well as the mechanism for correction of vocalization and articulation using auditory verbal feedback system. In this study, we confirmed the importance of the supplementary motor area for programing the articulatory movement and the cerebellum for the adjustment of vocalization. Wa also proved the time course of cortical processing for speech production to be sequential and parallel, which demonstrated the reasonable function of brain. Less