听觉皮层信号处理

听觉系统和视觉系统的不同之处在于：听觉系统在外周感受器和听皮层间具有更长的皮层下通路和更多的突触联系。该特殊结构反应了听觉系统从复杂听觉环境中提取与行为相关信号的机制与其他感觉系统不同。听皮层神经信号处理包括两种重要的转换机制,声音信号的非同构转换以及从声音感受到知觉层面的转换。听觉皮层神经编码机制同时也受到听觉反馈和语言或发声过程中发声信号的调控。听觉神经科学家和生物医学工程师所面临的挑战便是如何去理解大脑中这些转换的编码机制。我将会用我实验室最近的一些发现来阐述听觉信号是如何在原听皮层中进行处理的,并讨论其对于言语和音乐在大脑中的处理机制以及设计神经替代装置诸如电子耳蜗的意义。我们使用了结合神经电生理技术和量化工程学的方法来研究这些问题。     

耳蜗及听觉感受器

听觉系统是接受、传输、分析、处理声音信息的特殊感觉系统。从20世纪70年代至今对听觉系统的研究进展迅速。耳蜗足听觉感受器所在之处,其结构复杂,但中学生物学教材中对耳蜗结构阐述很简单,一些中学教师对耳蜗的结构了解较少,冈此本文就耳蜗的解剖结构及生理功能作一介绍、     

耳蜗微音电位数学模型及其应用——一种分离听神经动作电位的新方法

本文用生物控制论方法研究声波—耳蜗微音电位系统,建立了该系统的数学模型,提出了一种以此为基础的分离听神经动作电位的新方法.在耳蜗电位中将该模型预测出的微音电位成份减掉,便得到单独的听神经动作电位.与国内外通行使用的声音交替倒相迭加法相比,本文提出的方法有不改变听神经发放时间,可用于较复杂声音引起的耳蜗电位分析等优点,对听觉生理基础研究和耳科临床实践都有实用意义,对人工耳蜗声电特性的设计也提供了依据.     

人工耳蜗技术:过去、现在与未来

人工耳蜗技术可以帮助绝大多数重度-极重度感音神经性聋患者恢复听力,此项技术最早始于1800年意大利物理学家Alessandro Volta发现电刺激正常耳可以产生听觉. 20世纪60年代开始进入实用阶段,技术发展的方向包括单通道和多通道技术, 1979年北京协和医院单通道人工耳蜗研制成功, 1980年完成了国内第一例人工耳蜗植入术, 1995年5月,完成国内第一例多通道人工耳蜗植入.随着技术的进步,逐渐出现声电联合刺激人工耳蜗、双侧人工耳蜗植入、机器人辅助人工耳蜗植入等, 2012年北京协和医院在国内首次植入声电联合刺激人工耳蜗,双侧人工耳蜗植入研究也位于国内前列.随着手术成功经验越来越多,人工耳蜗适应症逐渐放宽, 2008年北京协和医院在国内首次研发成功术前电刺激听觉诱发电位技术,大量疑难复杂病例成功植入人工耳蜗.国内外也积极开展单侧耳聋的人工耳蜗植入、神经性耳鸣的人工耳蜗植入应用研究以及机器人辅助下人工耳蜗植入.上海交通大学医学院附属第九人民医院于2020年报道国内首例机器人辅助下人工耳蜗植入.同时光学人工耳蜗的研究也进入实验阶段.本文综述了人工耳蜗技术的国内外发展史、目前技术拓展以及未来发展趋势,以期为人工耳蜗的技术进步提供参考.     

听觉信息的编码

听觉系统能感受的声音干变万化,其参数变异范围极大,如频率上下限可相差1000倍,强度按能量计算上下限可相差10000倍。那么听觉系统是如何对如此巨量的听觉信息进行编码的呢？我们知道,声波经过耳蜗毛细胞的换能作用转变为神经冲动,成为传递声音的信息。但神经冲动是以全或无形式传布的,单纤维的神经冲动其振幅和与波形都是相对固定的,因此神经冲动的振幅波形不能反映声音的特性,只能依据神经冲动的节律、冲动的时间间隔以及发放神经冲动的纤维在耳蜗基底膜上的起源部位来传递不同形式的声音信息。我们把神经冲动在听神经纤维上传输…     

植入式微型磁力助听器

据报导,美国弗吉尼亚大学耳鼻喉科学系的科研人员目前正在研制开发一种全新的植入式微型磁力助听器。这种新式的听觉装置采用植入耳内的微型传感器截获声音,然后声音穿过植入耳内的微处理器和电磁线圈,经过处理和放大后的颤声经附着在内耳上的小园窗上的一块铅笔尖大小的磁体,即耳蜗一端的一个薄膜传递到内耳中,磁体将颤声送过耳蜗,并刺     

催产素对强噪声所致声音强度辨别功能损伤的拮抗作用

我们已发现外源性催产素能改善人及豚鼠以恼干电位或耳蜗电图为指标的听觉功能。本文在对照组和预先给予催产素处理的豚鼠上,比较了125dB(SPL)白噪声暴露20min前后声音强度辨别能力的改变,并比较了肌内注射和侧脑室微量注射两种不同给药途径的作用。实验以重复短声调幅引起的皮层慢反应电位阈值I_r为指标,观察了催产素对豚鼠声音强度辨别功能的影响。结果发现对照组噪声暴露所致I_r的升高明显高于催产素处理组,且此种暂时性阈移的恢复也明显慢于催产素组;催产素两种给药途径的结果无明显差异。这些结果进一步提示催产素对声音强度辨别功能具有保护作用。     

法国鹌鹑延髓听觉中枢——耳蜗核定位研究

本文将辣根过氧化物酶（ＨＲＰ）注入鹌鹑耳蜗内,应用ＨＲＰ在行标记方法对耳蜗核进行了研究,结果在同侧的角核和前庭外侧核发现有密集的标记终未,结果表明延髓的角核和前庭外侧是组成延髓听觉中枢－－耳蜗核的两个亚核,耳蜗核是听觉上行通路中在脑内的第一级神经元的换元站。     

虎皮鹦鹉耳蜗感觉细胞的发育与听觉的关系

选用18d、38d、成鸟(3月以上)三种年龄的雄性虎皮鹦鹉作为实验材料,采用测量脑干听觉诱发电位和制作内耳的石蜡切片两种方法,研究了鸟类在发育时期耳蜗感觉上皮细胞的变化以及听觉功能的发育状况。鸟的听觉能力在出生后不断得到提高,38d基本达到成鸟的水平;耳蜗毛细胞的形态、内部结构逐渐趋于成熟,其灵敏度不断提高,感受听觉的能力也在增强,38d基本与成鸟的发育程度相同。耳蜗感觉上皮细胞的发育对听觉行为产生的时间和发展具有极为重要的影响。     

经豚鼠下鼓道口记录耳蜗电图

豚鼠是听觉机能研究最常应用的动物,在其颅骨的鼓泡上,有一卵圆形的小孔,称为下鼓道口,在此插入电极,可抵鼓岬部,能够很好地记录出耳蜗电图。此方法简便、可靠,不需要打开乳突,是从鼓岬部记录耳蜗电图的一种新途径,在听觉机能研究及生理学实验教学中具有广泛的应用价值。     

Restoring hearing with active hearing implants.

Due to shortcomings of conventional hearing aid technology, such as unsatisfactory sound quality due to limited frequency range and undesired distortion, occlusion of the outer ear canal, and acoustic feedback with high amplification, but also psychological aspects of stigmatization, a significant of patients in need of hearing aids are actually not wearing them. Active hearing implants can be distinguished in: (1) impedance transformation implants (ITI), (2) cochlear amplifier implants (CAI), (3) cochlear implants (CI), and (4) brain stem implants (BSI). Whereas ITI are designed for patients with middle ear hearing loss, CAI are intended to restore hearing in patients with inner ear hearing loss. Advantages of CAI may be: (1) improved sound fidelity, (2) no occlusion of the outer ear canal, (3) no feedback, and (4) invisibility. However, not all features are true for every device. CI replace inner ear function in deaf or almost deaf patients. This article gives an overview on the range of active hearing implants to restore hearing and outlines the future use of computer and robot aided surgery.     

Color and communication in the dreams of hearing and deaf persons.

Research suggests that the experiences recollected from the dreams of persons who are deaf or who have hearing loss reflect their personal background and circumstances. However, this literature also indicated that few studies have surveyed the occurrence of color and communication styles. Individual differences in the perception of color and affect were especially noted. These differences appeared dependent upon whether the impairment was congenital or acquired. In this study, 24 deaf persons and a person with hearing loss who use American Sign Language (ASL) were compared to a sample of hearing persons regarding colors and communication occurring in their dreams. Both groups were found to communicate in dreams as they do in life, deaf persons and person with hearing loss by signing, and hearing persons by speech. The deaf persons and a person with hearing loss experienced more color and more vividness, and the time of onset for a hearing impairment showed differences among persons with hearing loss. The findings also suggest that utilizing dreams as therapeutic material when treating persons with hearing loss and nonimpaired persons may have clinical utility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory rehabilitation

Auditory rehabilitation depends of the cause and the severity of the hearing loss (or deafness). Hearing losses dues to middle ear pathologies can beneficiate of medical or surgical treatments, by ossicular prostheses, if it is necessary to restore the function of the ossicles chain. In the sensorineural hearing losses, with inner ear pathology, the use of auditory aid is immediately considered. In the cases for which they are insufficient because of severity of the hearing loss or not suitable because of local non-tolerance, it is possible to use middle ear implant or cochlear implant. The indications of the auditory brainstern implants remain at this day limited to the total bilateral hearing losses due to a complete destruction of cochleae and auditory nerves. These therapeutic orientations are selected after a multidisciplinary evaluation of the deaf person, evaluation that allows the characterization of the hearing loss and its repercussion. In all the cases, the restoration of a bilateral hearing has to be done if possible, making an improvement of the speech comprehension, mainly in the noisy situations, as well as the localization of the sound sources.     

Recall in acoustically similar and dissimilar letters by normal and deaf subjects.

Stimulus matrices with 4 X 3 letters from an acoustically similar and dissimilar alphabet were presented tachystoscopically for 5 secs to 41 Ss divided into three groups, i.e. normal and deaf apprentices and deaf children. Each S was administered 42 stimulus matrices. While the difference in the number of errors between the acoustically similar and dissimilar alphabets proved significant in the hearing Ss, it was nonsignificant in the deaf, and in contrast to these two groups, in the children the number of errors with the acoustically similar alphabet was lower than with the dissimilar one. The error matrices indicate a systematic course of errors and their different pattern for the hearing and the deaf Ss. A visual and an articulating code which is reinforced by the length of oral training, may be presumed particularly in the deaf.     

Marital Structure,Genetic Fitness,and the <Emphasis Type="Italic">GJB2</Emphasis> Gene Mutations among Deaf People in Yakutia (Eastern Siberia,Russia)

Autosomal recessive deafness type 1A (DFNB1A) caused by mutations in the GJB2 gene (Cx26) is the main cause of nonsyndromic hearing impairment in many populations worldwide. It is considered that widespread prevalence of DFNB1A can be due to the long tradition of intermarriages between deaf people (assortative marriages) combined with their increased social adaptation and genetic fitness after widespread introduction of sign language. For the first time, the data on mating structure and reproduction of deaf people living in Yakutia (Eastern Siberia, Russia) are presented in comparison with contribution of the GJB2 gene mutations to the etiology of hearing impairment. The relative fertility of deaf people compared to their hearing siblings is 0.78 (mean number of children 1.76 ± 0.10 and 2.24 ± 0.09 to deaf and their hearing siblings, respectively, p = 0.0018). The rate of assortative marriages among deaf people is 77.1% (81 of 105 marriages). Biallelic mutations in the GJB2 gene were found in 42.2% (43 of 102) of examined deaf people, which corresponded to diagnosis DFNB1A for these patients. A comparison of deaf marital partners by GJB2 status revealed a proportion of noncomplementary marriages (24%) in which hearing loss in both partners was caused by the presence of biallelic GJB2 gene mutations resulting in the birth of only deaf children in such couples. Thus, the set of obtained data including a relatively high genetic fitness (expressed as relative fertility) of deaf people in Yakutia in combination with a high rate of assortative marriages among them and high incidence of DFNB1A indicates a possible weakening of selection against such trait as “deafness” and a possible increase in the frequency of GJB2 mutant alleles in subsequent generations.     

Low Empathy in Deaf and Hard of Hearing (Pre)Adolescents Compared to Normal Hearing Controls

Objective

The purpose of this study was to examine the level of empathy in deaf and hard of hearing (pre)adolescents compared to normal hearing controls and to define the influence of language and various hearing loss characteristics on the development of empathy.

Methods

The study group (mean age 11.9 years) consisted of 122 deaf and hard of hearing children (52 children with cochlear implants and 70 children with conventional hearing aids) and 162 normal hearing children. The two groups were compared using self-reports, a parent-report and observation tasks to rate the children’s level of empathy, their attendance to others’ emotions, emotion recognition, and supportive behavior.

Results

Deaf and hard of hearing children reported lower levels of cognitive empathy and prosocial motivation than normal hearing children, regardless of their type of hearing device. The level of emotion recognition was equal in both groups. During observations, deaf and hard of hearing children showed more attention to the emotion evoking events but less supportive behavior compared to their normal hearing peers. Deaf and hard of hearing children attending mainstream education or using oral language show higher levels of cognitive empathy and prosocial motivation than deaf and hard of hearing children who use sign (supported) language or attend special education. However, they are still outperformed by normal hearing children.

Conclusions

Deaf and hard of hearing children, especially those in special education, show lower levels of empathy than normal hearing children, which can have consequences for initiating and maintaining relationships.     

Neuroprosthetic hearing with auditory brainstem implants.

The auditory brainstem implant (ABI) does provide auditory sensations, recognition of environmental sounds and aid in spoken communication in about 300 patients worldwide. It is no more an investigative device but widely accepted for the treatment of patients who have lost hearing due to bilateral tumors of the hearing nerve who transmits the acoustic information from the cochlea to the brain. Most of the implanted patients are completely deaf when the implant is switched off. In contrast to cochlear implants, only few of the implanted patients achieve open-set speech recognition without the help of visual cues. On average, the ABI improves communicative functions like speech recognition at about 30% when compared to lip-reading only. The task for the next years is to improve the outcome of ABI further by developing new less invasive operative approaches as well as new hardware and software for the ABI device.     

Examining Interactions across Language Modalities: Deaf Children and Hearing Peers at School

Deaf youth easily become communicatively isolated in public schools, where they are in a small minority among a majority of hearing peers and teachers. This article examines communicative strategies of deaf children in an American "mainstream " school setting to discover how they creatively manage their casual communicative interactions with hearing peers across multimodal communicative channels, visual and auditory. We argue that unshared sociolinguistic practices and hearing-oriented participation frameworks are crucial aspects of communicative failure in these settings. We also show that what look like "successful" conversational interactions between deaf and hearing children actually contain little real language and few of the complex communication skills vital to cognitive and social development. This study contributes to understanding the social production of communicative isolation of deaf students and implications of mainstream education for this minority group.     

Effect of Exogenous Cues on Covert Spatial Orienting in Deaf and Normal Hearing Individuals

Deaf individuals have been known to process visual stimuli better at the periphery compared to the normal hearing population. However, very few studies have examined attention orienting in the oculomotor domain in the deaf, particularly when targets appear at variable eccentricity. In this study, we examined if the visual perceptual processing advantage reported in the deaf people also modulates spatial attentional orienting with eye movement responses. We used a spatial cueing task with cued and uncued targets that appeared at two different eccentricities and explored attentional facilitation and inhibition. We elicited both a saccadic and a manual response. The deaf showed a higher cueing effect for the ocular responses than the normal hearing participants. However, there was no group difference for the manual responses. There was also higher facilitation at the periphery for both saccadic and manual responses, irrespective of groups. These results suggest that, owing to their superior visual processing ability, the deaf may orient attention faster to targets. We discuss the results in terms of previous studies on cueing and attentional orienting in deaf.