用于听觉图象再现的实验系统

本文给出了一个用于将图象转换成声音形式的实验系统。该系统可以在某些已知的人类听觉系统的极限内提供听觉图象的再现,这可能是向为盲人设计的视觉替换仪器的发展所迈进的一步。一种可逆(1:1)的图象——声音转换方法的应用保证了视觉信息的保存。系统式工具包括一个连到标准电视摄象机上的带有管道的特殊用途的计算机。由一种实时图象(声音转换方法得到的时分复用声音再现)可以再现出分辨率大于64×64个象素点且每个象素点有16个灰阶的图象。我们已经采用新颖的设计并使用标准元件制成了一个具有适合于电池操作的低价格便携式实验性转换系统。对系统输出进行的计算机采样和随     

基于虚拟仪器技术的超声波导盲系统的研制

超声波非常适合应用于导盲系统。本文构造了一种某于虚拟仪器技术的超声波导盲系统研究平台。我们获得障碍物的距离信息和超声回波的强度信息，进行音频调制，向盲人提供更加丰富的信息。本文从系统组成、软硬件设计等方面阐述了该虚拟仪器平台。     

盲人视皮层重塑的探讨

大脑可塑性是大脑的主要属性之一,研究大脑可塑性对于揭示大脑活动的规律具有十分重要的意义。很早以前,人们就发现盲人虽然视觉缺失,但是他们的其他功能,如触觉、听觉等都好于正常人,为什么盲人这些方面的功能会好于正常人?研究盲人视皮层重塑对于了解大脑可塑性有着十分重要的作用。20世纪末,学者们开始利用正电子发射断层扫描(PET)、透颅磁刺激(transcranial magnetic stimulation,TMS)、功能磁共振成像(functional magnetic resonance imaging,FMRI)等技术研究盲人视皮层重塑,发现盲人在阅读盲文时,视皮层会被激活,由此得出盲人视皮层重塑的理论依据。但是,目前关于盲人视皮层重塑的机制尚不清楚,如在盲人视皮层重塑的过程中大脑的结构和功能到底发生了哪些变化?诱导大脑结构和功能发生变化的内在机制是什么?本文将结合神经解剖学、神经组织学、神经生理学、认知神经科学等学科的理论探讨盲人视皮层重塑的机制。     

盲人特异视觉的诱发训练与眼睛的关系研究

本文叙述了以盲人为实验模型，对盲人，低视儿童及正常小学生进行了特异视觉的诱发训练研究。结果表明，特异视觉能否出现似乎与他们眼睛的视力丧失程度有关。部分盲人可以通过诱发训练特异视觉获得视觉补偿，文中还对特异视觉与眼睛的关系进行了分析讨论。     

汉语听写障碍儿童形音跨通道捆绑加工的通道优势

目的:研究汉语听写障碍儿童在形音跨通道捆绑过程中的视觉和听觉跨通道优势。方法:以听写障碍儿童21名,正常发展儿童21名为被试。采用变化检测范式,以几何图形为视觉刺激材料,以单音节男声为听觉刺激材料,通过考察两组儿童在探测形音跨通道不一致、视觉单通道不一致、听觉单通道不一致三种条件下的正确率,探索听写障碍儿童与正常发展儿童在形音捆绑过程中的跨通道整合优势以及视觉或听觉单通道的优势效应。结果:听写障碍儿童在视听跨通道加工条件下显著地低于正常发展儿童,在视觉单通道条件下两者差异不显著,在听觉单通道条件下两者差异达到边缘显著。结论:听写障碍儿童的形音捆绑缺陷来自于跨通道本身的缺陷。正常听写儿童可能具有听觉单通道加工优势。听写障碍儿童在形音捆绑加工中有和正常听写儿童相同的视觉通道优势,但有可能在听觉通道中不占优势。     

视听觉刺激下大脑头皮电位空间变化特性

目的:脑机接口（BCI）技术可以为肢体残障人士提供一种新的交流方式,在医疗康复领域具有很好的应用前景。目前单一视觉刺激的BCI系统难以适用于实际场合中多感觉信息输入的情况,需要进一步了解听觉刺激对视觉诱发电位的影响,为视听混合刺激下的BCI技术研究提供依据。 方法:在闪光刺激为12和42 Hz条件下分别加入12和42 Hz的听觉刺激,研究听觉刺激的加入对视觉刺激下大脑头表额、枕、中央、顶、颞5个空间点脑电功率的影响。 结果:视听脉冲同时刺激条件下,枕区脑电功率最大,其余空间点的功率随测试点到枕区距离的增加而减少;与单一视觉刺激下空间某点的脑电功率相比,听觉刺激的加入对该点脑电功率起增强还是抑制作用,主要取决于该点的空间位置。 结论:研究结果为听觉刺激和视觉刺激在BCI中的整合及多模态脑机接口的研究提供有意义的实验依据。     

低视力及其导致的心理社会问题概述

人从外界环境中接受各种信息时 ,约 90 %以上的信息从视觉通道输入。因此 ,视觉的敏锐与否对劳动、学习和生活的能力影响很大[1] 。随着人口老龄化趋势的发展 ,一些导致视功能损害的疾病 ,如 :黄斑变性、糖尿病性视网膜病变、青光眼等疾病的发病率日益增高。据调查在美国 70岁以上的老年人中 ,低视力已经仅次于关节炎、心脏病而成为第三位患者在日常生活中需要照料的慢性状况[2 ,3 ] 。盲及低视力不仅影响患者的日常生活 ,而且还引起患者一系列的心理社会问题。关于盲人的心理社会问题 ,国内外研究较早 ,文献也较多[4 ,5-9] 。关于低视力患…     

视觉听觉同时刺激模式下ERP的同步性研究

目的：研究视觉、听觉脑区在认知过程中的同步性。方法：设计了视觉、听觉同时刺激模式下的脑电实验，采用128道高密度脑电采集系统，记录了14位年龄在18～29岁之间的在校男性大学生的诱发脑电信号数据，并运用希尔伯特(Hilbert)相位同步算法对视觉、听觉区域的事件相关电位(ERP)进行同步量化。结果：在视听觉同时利用模式下，视觉脑区(枕叶)和听觉脑区(颞叶)之间的同步指数明显大于它们与其他脑区间的同步指数。结论：人在感知和认知事物时，相关的脑区间自动产生了神经活动的同步化。     

听觉脑-机接口技术实验范式的研究进展

目前基于视觉范式的脑-机接口技术研究已经取得了较大的突破,并在实际中得到了广泛应用.然而很多视力受损的闭锁综合症患者,无法使用基于视觉范式的脑-机接口系统,因此研究这一技术是非常必要的,可为听觉正常的闭锁综合症患者提供了一种新的与外界交流的渠道.本研究回顾了基于听觉范式的脑-机接口技术研究现状,从听觉P300、稳态听觉诱发电位、选择注意以及空间定位等4个方面总结归纳了听觉脑-机接口技术的实验范式并进行分析对比.最后提出了听觉脑-机接口技术在实际应用中存在的问题,并探讨了进一步的研究方向及思路.     

盲人助视器研究的现状

为盲人重新获得视觉既是科学工作者面临的任务,也是人们普遍关注的问题。估计1975年,全世界盲人达1800万人。直到不久以前,盲人的行动主要靠探路棍,盲人的教育和职业条件主要依靠简单的触觉,这些只能给盲人极有限的帮助。现代科学技术的发展,新兴的电子科学和计算机技术的广泛应用,生物医学工程学、仿生学等各学科领城的相应进展,促进     

Axon guidance cues in auditory development

The innervation of the cochlear sensory epithelium is intricately organized, allowing the tonotopy established by the auditory hair cells to be maintained along the ascending auditory pathways. These auditory projections are patterned by several gene families that regulate neurite attraction and repulsion, known as axon guidance cues. In this review, the roles of various axon guidance molecules, including fibroblast growth factor, ephs, semaphorins, netrins and slits, are examined in light of their known contribution to auditory development. Additionally, morphogens are discussed in the context of their recently described influence on axonal pathfinding in other sensory systems. The elucidation of these various mechanisms may guide the development of therapies aimed at maximizing the connectivity of auditory neurons in the context of congenital or acquired sensorineural hearing loss, especially as pertains to cochlear implants. Further afield, improved understanding of the molecular processes which regulate innervation of the organ of Corti during normal development may prove useful in connecting regenerated hair cells to the central nervous system.     

Eph and ephrin signaling in the development of the central auditory system

Acoustic communication relies crucially on accurate interpretation of information about the intensity, frequency, timing, and location of diverse sound stimuli in the environment. To meet this demand, neurons along different levels of the auditory system form precisely organized neural circuits. The assembly of these precise circuits requires tight regulation and coordination of multiple developmental processes. Several groups of axon guidance molecules have proven critical in controlling these processes. Among them, the family of Eph receptors and their ephrin ligands emerge as one group of key players. They mediate diverse functions at multiple levels of the auditory pathway, including axon guidance and targeting, topographic map formation, as well as cell migration and tissue pattern formation. Here, we review our current knowledge of how Eph and ephrin molecules regulate different processes in the development and maturation of central auditory circuits.     

听皮层可塑性的研究进展

听皮层(auditory cortex,AC)通过其自身结构和功能特征的动态变化即可塑性来适应不断变化的外界环境或接收重要信息的输入。早期经历、听觉联合型学习、外周听觉系统的损伤、丰富环境等因素对听皮层的可塑性有重要影响,同时还发现胆碱能纤维、皮层下行纤维等在听皮层可塑性的调控中起重要作用。     

Use It or Lose It? Lessons Learned from the Developing Brains of Children Who are Deaf and Use Cochlear Implants to Hear

In the present paper, we review what is currently known about the effects of deafness on the developing human auditory system and ask: Without use, does the immature auditory system lose the ability to normally function and mature? Any change to the structure or function of the auditory pathways resulting from a lack of activity will have important implications for future use through an auditory prosthesis such as a cochlear implant. Data to date show that deafness in children arrests and disrupts normal auditory development. Multiple changes to the auditory pathways occur during the period of deafness with the extent and type of change being dependent upon the age and stage of auditory development at onset of deafness, the cause or type of deafness, and the length of time the immature auditory pathways are left without significant input. Structural changes to the auditory nerve, brainstem, and cortex have been described in animal models of deafness as well in humans who are deaf. Functional changes in deaf auditory pathways have been evaluated by using a cochlear implant to stimulate the auditory nerve with electrical pulses. Studies of electrically evoked activity in the immature deaf auditory system have demonstrated that auditory brainstem development is arrested and that thalamo-cortical areas are vulnerable to being taken over by other competitive inputs (cross-modal plasticity). Indeed, enhanced peripheral sight and detection of visual movement in congenitally deaf cats and adults have been linked to activity in specific areas of what would normally be auditory cortex. Cochlear implants can stimulate developmental plasticity in the auditory brainstem even after many years of deafness in childhood but changes in the auditory cortex are limited, at least in part, by the degree of reorganization which occurred during the period of deafness. Consequently, we must identify hearing loss rapidly (i.e., at birth for congenital deficits) and provide cochlear implants to appropriate candidates as soon as possible. Doing so has facilitated auditory development in the thalamo-cortex and allowed children who are deaf to perceive and use spoken language.     

Genetics,genomics and gene discovery in the auditory system

The sounds of silence have forever been broken as genetics and genomics approaches in human and model organisms have provided a powerful and rapid entry into gene discovery in the auditory system. An understanding of the complexities and beauty of the biological process of hearing itself is unfolding as genes underlying hereditary hearing impairment are identified. Genes involved in modifying hearing are also being found, and will be critical to a full comprehension of genotype-phenotype relationships. Investigations in the auditory system will provide important insight into how the nervous system decodes molecular information. Deafness represents a common sensory disorder that can interfere dramatically in the acquisition of speech and language in children, and in the quality of life for a growing aged population. As newborn screening for hearing impairment is being implemented in many birth hospitals, the prospects for precise clinical diagnosis, appropriate genetic counseling and proper medical management for auditory disorders has never been at a more exciting crossroad.     

Sensorimotor integration in the primate superior colliculus. I. Motor convergence

Orienting movements of the eyes and head are made to both auditory and visual stimuli even though in the primary sensory pathways the locations of auditory and visual stimuli are encoded in different coordinates. This study was designed to differentiate between two possible mechanisms for sensory-to-motor transformation. Auditory and visual signals could be translated into common coordinates in order to share a single motor pathway or they could maintain anatomically separate sensory and motor routes for the initiation and guidance of orienting eye movements. The primary purpose of the study was to determine whether neurons in the superior colliculus (SC) that discharge before saccades to visual targets also discharge before saccades directed toward auditory targets. If they do, this would indicate that auditory and visual signals, originally encoded in different coordinates, have been converted into a single coordinate system and are sharing a motor circuit. Trained monkeys made saccadic eye movements to auditory or visual targets while the activity of visual-motor (V-M) cells and saccade-related burst (SRB) cells was monitored. The pattern of spike activity observed during trials in which saccades were made to visual targets was compared with that observed when comparable saccades were made to auditory targets. For most (57 of 59) V-M cells, sensory responses were observed only on visual trials. Auditory stimuli originating from the same region of space did not activate these cells. Yet, of the 72 V-M and SRB cells studied, 79% showed motor bursts prior to saccades to either auditory or visual targets. This finding indicates that visual and auditory signals, originally encoded in retinal and head-centered coordinates, respectively, have undergone a transformation that allows them to share a common efferent pathway for the generation of saccadic eye movements. Saccades to auditory targets usually have lower velocities than saccades of the same amplitude and direction made to acquire visual targets. Since fewer collicular cells are active prior to saccades to auditory targets, one determinant of saccadic velocity may be the number of collicular neurons discharging before a particular saccade.     

Concise review: the potential of stem cells for auditory neuron generation and replacement

Sensory hair cells in the mammalian cochlea are sensitive to many insults including loud noise, ototoxic drugs, and ageing. Damage to these hair cells results in deafness and sets in place a number of irreversible changes that eventually result in the progressive degeneration of auditory neurons, the target cells of the cochlear implant. Techniques designed to preserve the density and integrity of auditory neurons in the deafened cochlea are envisaged to provide improved outcomes for cochlear implant recipients. This review examines the potential of embryonic stem cells to generate new neurons for the deafened mammalian cochlea, including the directed differentiation of stem cells toward a sensory neural lineage and the engraftment of exogenous stem cells into the deafened auditory system. Although still in its infancy the aim of this therapy is to restore a critical number of auditory neurons, thereby improving the benefits derived from a cochlear implant.     

Early experience shapes vocal neural coding and perception in songbirds

Songbirds, like humans, are highly accomplished vocal learners. The many parallels between speech and birdsong and conserved features of mammalian and avian auditory systems have led to the emergence of the songbird as a model system for studying the perceptual mechanisms of vocal communication. Laboratory research on songbirds allows the careful control of early life experience and high-resolution analysis of brain function during vocal learning, production, and perception. Here, I review what songbird studies have revealed about the role of early experience in the development of vocal behavior, auditory perception, and the processing of learned vocalizations by auditory neurons. The findings of these studies suggest general principles for how exposure to vocalizations during development and into adulthood influences the perception of learned vocal signals.     

Responses to Achilles tendon vibration during self-paced,visually and auditory-guided periodic sway

Achilles tendon vibration (ATV) alters proprioceptive input of the triceps surae muscles resulting in a posterior postural shift during standing. When this is applied in combination with a more dynamic proprioceptive perturbation, postural responses to ATV are attenuated. In this study, we applied ATV during self-paced, visually and auditory guided voluntary periodic sway in order to examine how the vibration-induced afferent input is processed and reweighted at the presence of inter-sensory guidance stimuli. Seventeen healthy adults (aged 26.7 ± 4.23 years) performed 15 cycles of periodic sway under three sensory guidance conditions: (a) self-paced, (b) auditory paced (0.25 Hz), and (c) visually driven by matching the resultant force vector to a target sine-wave (0.25 Hz). Bilateral ATV (80 Hz, 3 mm) was applied between the 5th and 10th sway cycles. ATV evoked an earlier burst onset and increased activity of the plantarflexors consistent with a reduction in the amplitude and duration of forward sway. This in turn resulted in an increase in dorsiflexors’ activity in order to compensate for the greater backward sway. Postural responses to ATV were augmented when sway was auditory and visually guided. Forward sway variability increased with ATV and remained high while backward sway variability decreased in the post-vibration phase. Our results suggest that sensory context-dependent constraints that determine the degree of active control of posture and associated postural challenge involved in a particular task determine how the vibration-induced Ia afferent input will be registered and further processed by the central nervous system.     

Dynamic shifts in the owl's auditory space map predict moving sound location

The optic tectum of the barn owl contains a map of auditory space. We found that, in response to moving sounds, the locations of receptive fields that make up the map shifted toward the approaching sound. The magnitude of the receptive field shifts increased systematically with increasing stimulus velocity and, therefore, was appropriate to compensate for sensory and motor delays inherent to auditory orienting behavior. Thus, the auditory space map is not static, but shifts adaptively and dynamically in response to stimulus motion. We provide a computational model to account for these results. Because the model derives predictive responses from processes that are known to occur commonly in neural networks, we hypothesize that analogous predictive responses will be found to exist widely in the central nervous system. This hypothesis is consistent with perceptions of stimulus motion in humans for many sensory parameters.