数值模拟人双耳感受体位变化的机制

目的探究双耳3对半规管在感受有角运动时力学行为表达的规律。方法采用有限元法数值模拟一例健康人头部水平正弦转动时左、右耳3对半规管的力学响应。结果各平衡感受器嵴顶局部位移响应随着嵴顶位置改变而变化,但是3对嵴顶的体积应变响应是规律的,每对嵴顶均以与激励相同的频率等幅度膨胀或收缩。水平、前、后半规管3个嵴顶的体积应变幅值绝对值的比值恒定,近似为1.00︰0.80︰1.72。此外,水平半规管和前半规管嵴顶体积应变响应的相位相同,且与头转动速度的相位约相差14.4°,与后半规管嵴顶体积应变响应的相位相差180°。结论嵴顶体积应变可以较好地表征3对半规管感受有角运动的规律,其幅值、频率和相位可以分别反映刺激角速度的幅值、频率和相位,这一规律为进一步建立前庭眼反射的数量依存关系奠定基础,同时为眼震检查定量评估前庭功能提供理论依据。     

数值模拟前庭系统膜迷路的生物力学响应

目的研究平衡感受器嵴顶对旋转椅试验的生物力学响应,为前庭系统功能状态的评估提供定量分析的平台。方法基于健康志愿者右侧颞骨完整的组织切片数据进行三维几何重建。运用拉格朗日法数值模拟头前倾30毅、频率0.8Hz、幅度依40毅的正弦摆动旋转椅试验中受试者前庭系统膜迷路的生物力学响应。结果右耳水平半规管嵴顶峰值位移为54.2μm,后规管嵴顶峰值位移为15.9μm;右耳前半规管嵴顶峰值位移为43.7μm,但是左右耳响应相同,对眼球运动的作用相互抵消;向右旋转,右耳水平半规管壶腹嵴嵴顶法向位移从管侧偏向椭圆囊侧,左耳水平半规管壶腹嵴嵴顶法向位移从椭圆囊侧偏向管侧,向左旋转时则相反。结论数值模拟得到的嵴顶的生物力学响应符合Flourens定律和Ewald定律。     

半规管与动物敏捷度

正半规管是脊椎动物内耳的一个古老组成部分。在有颌动物(有颌骨的脊椎动物)的听泡中,骨性管道和其中的膜性管道组成了半规管,每侧听泡中各有上、外、后3个半规管,代表空间3个不同的平面,分别感受运动过程中头部在不同方向的旋转~([1])。大脑将半规管的传人冲动与耳石、视觉和本体感觉的信息进行整合分析,进而调整运动过程中躯体的姿势和动作~([2])。注视锁定是半规管最重要的功能之一,这一功能是通过前庭眼反射和前庭丘反射实现的,在运动中眼外肌和颈部肌肉需要配合躯体     

上半规管良性阵发性位置性眩晕诊断试验分析和物理引擎耳石运动观察

目的 对上半规管良性阵发性位置性眩晕（BPPV）诊断试验进行分析，了解其诊断机制。方法 建立标准空间坐标系的膜迷路模型，设定膜迷路不同位置结石，基于物理引擎三维物理仿真，分析Dix Hallpike试验和仰卧悬挂头位试验耳石运动情况，进而推断所诱发眼震表现。结果 Dix-Hallpike试验和仰卧悬挂头位试验所有位置的结石都有一定程度的运动，并能诱发椭圆囊的结石经总管进入半规管。出现下跳眼震的情况，包括结石从椭圆囊进入后半规管，对侧后半规管结石向壶腹运动，上半规管的结石从壶腹嵴帽底部滑动到顶部，后者重复诊断实验仍为下跳眼震。重复10次观察，试验结果一致。结论 对于上半规管BPPV的诊断标准，还需要重新评估，观察眼震动态变化是必要的，其诊断方法需要改良。     

眼动系统研究

Ⅲ前庭眼动系统引言如[1]所述,眼动系统的输出都是眼动信号EOG(Electro oculargraph),然而随着刺激的不同,系统会有不同的神经通路,不同的解剖生理构成。本文研究的眼动信号是典型的眼震图ENG(Electronystagmograph)。众所周知,前庭器官中的半规管是人体运动平衡系统中的重要组成部分,担负着角加速     

正常成人内耳系统液体容积的磁共振测量与分析

目的 探讨磁共振三维水成像技术在内耳液体容积测量中的应用价值.方法 30例正常成人志愿者均采用GE1.5T磁共振机、8通道头部相控阵线圈,行内耳内听道水成像序列扫描(三维真稳态进动快速成像序列),所采集信号传送至工作站AW4.2进行多平面重建和容积重建,测量耳蜗、前庭-半规管和内听道容积,初步建立其正常值范围,并分别比较耳别、性别及年龄段间有无差异.结果 30例(60耳)正常志愿者的耳蜗、前庭-半规管和内听道容积分别为(101.2±11.1)mm3、(151.5±19.9)mm3和(220.1±58.7) mm3;正常值范围分别为(79.4～123.0)mm3、(112.5～190.5)mm3和(105.0～335.2)mm3;变异系数分别为0.11、0.13和0.27.内耳系统液体容积在耳别、性别及年龄段间差异均无统计学意义(P＞0.05).结论磁共振三维水成像技术可用于活体内耳系统液体容积的测量,为临床上内耳腔道结构的评估及内耳畸形的分类、分型提供影像解剖学依据.     

基于磁共振数据的三维半规管建模空间方向测量

目的测量半规管相互夹角和空间方向。方法对16例磁共振3D-CISS序列内耳检查影像,分割半规管结构建立三维模型,生成3D PDF文件,在各半规管取3点坐标,通过数学方法对同侧和双侧的半规管相互夹角以及各半规管和水平面的夹角进行计算。结果左右后半规管夹角为98.49°±12.07°,可以推测后半规管和矢状面的夹角为49.25°±6.04°。左右水平半规管夹角为171.58°±3.78°;左侧后半规管和右侧前半规管夹角为165.56°±5.78°,右侧后半规管和左侧前半规管夹角为164.74°±6.46°,左侧水平半规管和水平面夹角为19.43°±3.02°,右侧水平半规管和水平面夹角22.11°±4.12°。结论左右共同平面对半规管近乎平行,后半规管和矢状面的夹角大于45°,两侧半规管总脚分叉点和眼球下缘平面更加接近水平面。     

外半规管良性阵发性位置性眩晕诊断试验分析和物理引擎耳石运动观察

目的对外半规管良性阵发性位置性眩晕(BPPV)诊断试验进行分析,了解其诊断机制。方法建立基于物理引擎三维物理仿真的BPPV迷路模型,设定外半规管不同位置结石,分析水平滚转试验过程不同位置耳石运动情况,进而可以推断所诱发眼震表现。结果水平滚转试验眼震表现形式多样,包括双侧背地眼震,可以判断为壶腹部结石和嵴帽结石,眼震弱侧为患侧;双侧向地眼震,可以判断为外半规管长臂侧结石,眼震强烈侧为患侧;一侧背地眼震一侧向地眼震,考虑长臂侧壶腹部结石;水平滚转试验存在的设计缺陷是会导致耳石复位,影响诊断试验的敏感性。10次重复试验结果一致。结论60°水平滚转试验有效修正了90°水平滚转试验存在的缺陷。基于物理引擎对诊断试验进行分析,对于我们理解外半规管BPPV的诊断机制有重要意义,也有助于改良和创新诊断方法。     

幕上、下乙状窦前入路的显微外科解剖学

目的:为幕上、幕下乙状窦前人路提供显微外科解剖学基础。方法:显微镜下对１５例成人尸体头部标本进行观察并测量有关数据。结果:迷路后、经迷路、经耳蜗入路骨质切除范围分别在后半规管最后点、内耳道、耳蜗和乙状窦沟之间。后半规管弓峰、内耳门后缘到乙状窦前缘的距离分别为(９．８±１．９)ｍｍ、(２２．０±２．４)ｍｍ,耳蜗到崖嵴最后点的距离为(２８．６±３．０)ｍｍ,岩嵴到颈静脉窝顶的距离为(１５．１±４．０)ｍｍ。结论:应用此入路能取得岩斜区病变手术治疗满意的结果。     

基于Matlab精确测量半规管在颅底中的方位

目的:确定半规管在颅底的精确方位,并分析其在不同年龄组、侧别和性别中的差异.方法:将45例正常人(90侧耳)的CT序列图像导入Mimics软件,读取确定半规管平面的标志点以及为确定以法兰克福平面为基准的标准空间坐标系的关键结构标志点的三维坐标,基于Matlab软件编制计算程序Laby Calculation,确定标准空间坐标系的相关方程,计算半规管在标准坐标系中的空间方位和面面夹角,最后对数据进行统计分析.结果:半规管的方位在不同年龄组和性别中具有一定的差异,而左右侧无明显差异,不同年龄组同侧半规管间面面夹角比较差异均无统计学意义(p＞0.05),提示随年龄增长同侧三个半规管方位的旋转可能是作为一个整体一同发生的.结论:本研究可为半规管发育研究提供形态数据,并对相关前庭功能检查和平衡功能障碍治疗提供依据和帮助.     

Spatial tuning and dynamics of vestibular semicircular canal afferents in rhesus monkeys

Rotational head motion in vertebrates is detected by the three semicircular canals of the vestibular system whose innervating primary afferent fibers encode movement information in specific head planes. In order to further investigate the nature of vestibular central processing of rotational motion in rhesus monkeys, it was first necessary to quantify afferent information coding in this species. Extracellular recordings were performed to determine the spatial and dynamic properties of semicircular canal afferents to rotational motion in awake rhesus monkeys. We found that the afferents innervating specific semicircular canals had maximum sensitivity vectors that were mutually orthogonal. Similar to other species, afferent response dynamics varied, with regular firing afferents having increased long time constants (t ₁), decreased cupula velocity time constants (t _v), and decreased fractional order dynamic operator values (s ^k) as compared to irregular firing afferents.     

Low-frequency otolith and semicircular canal interactions after canal inactivation

During sustained constant velocity and low-frequency off-vertical axis rotations (OVAR), otolith signals contribute significantly to slow-phase eye velocity. The adaptive plasticity of these responses was investigated here after semicircular canal plugging. Inactivation of semicircular canals results in a highly compromised and deficient vestibulo-ocular reflex (VOR). Based on the VOR enhancement hypothesis, one could expect an adaptive increase of otolith-borne angular velocity signals due to combined otolith/canal inputs after inactivation of the semicircular canals. Contrary to expectations, however, the steady-state slow-phase velocity during constant velocity OVAR decreased in amplitude over time. A similar progressive decrease in VOR gain was also observed during low-frequency off-vertical axis oscillations. This response deterioration was present in animals with either lateral or vertical semicircular canals inactivated and was limited to the plane(s) of the plugged canals. The results are consistent with the idea that the low-frequency otolith signals do not simply enhance VOR responses. Rather, the nervous system appears to correlate vestibular sensory information from the otoliths and the semicircular canals to generate an integral response to head motion.     

Foxg1 is required for proper separation and formation of sensory cristae during inner ear development

The vestibular portion of the inner ear, the three semicircular canals and their sensory cristae, is responsible for detecting angular head movements. It was proposed that sensory cristae induce formation of their non‐sensory components, the semicircular canals. Here, we analyzed the inner ears of Foxg1^?/? mouse mutants, which display vestibular defects that are in conflict with the above model. In Foxg1^?/? ears, the lateral canal is present without the lateral ampulla, which houses the lateral crista. Our gene expression analyses indicate that at the time when canal specification is thought to occur, the prospective lateral crista is present, which could have induced lateral canal formation prior to its demise. Our genetic fate‐mapping analyses indicate an improper separation between anterior and lateral cristae in Foxg1^?/? mutants. Our data further suggest that a function of Foxg1 in the inner ear is to restrict sensory fate. Developmental Dynamics 238:2725–2734, 2009. © 2009 Wiley‐Liss, Inc.     

Asymmetric integration recorded from vestibular-only cells in response to position transients

Angular and translational accelerations excite the semicircular canals and otolith organs, respectively. While canal afferents approximately encode head angular velocity due to the biomechanical integration performed by the canals, otolith signals have been found to approximate head translational acceleration. Because central vestibular pathways require velocity and position signals for their operation, the question has been raised as to how the integration of the otolith signals is accomplished. We recorded responses from 62 vestibular-only neurons in the vestibular nucleus of two monkeys to position transients in the naso-occipital and interaural orientations and varying directions in between. Responses to the transients were directionally asymmetric; one direction elicited a response that approximated the integral of the acceleration of the stimulus. In the opposite direction, the cells simply encoded the acceleration of the motion. We present a model that suggests that a neural integrator is not needed. Instead a neuron with a long membrane time constant and an excitatory postsynaptic potential duration that increases with the firing rate of the presynaptic cell can emulate the observed behavior.     

Displacement of the semicircular canal cupula during sinusoidal rotation.

The semicircular canal cupula has been described as a gelatinous partition of the ampulla which is displaced by the endolymph as if it were hinged at its receptor cell base. Subsequent studies have shown that during the artificial displacement of the endolymph, the cupula remains in position around its perimeter and is functionally displaced as a diaphragm. In this study the configuration and the magnitude of movement of the cupula during sinusoidal rotation was analyzed.Horizontal semicircular canal cupulae of bullfrogs were marked by microinjection of darkened oil droplets. Variable amplitudes of cupula displacement were achieved by sinusoidal rotation in the plane of the horizontal semicircular canal. The course of displacement was determined by analysis of individual dye droplets in cinematographic frames and compared to the turntable movement. Three findings demonstrate features of cupula movement and function. First, select regions of the cupula moved through peak amplitudes of 7.0 μm (peak to peak displacement, 14.0 μm) during sinusoidal rotation with peak angular velocities of 200 deg./s. The displacement of individual droplets was sinusoidal and followed the turntable position with a mean phase lag of about 64°. Second, the amplitude of displacement was dependent on the location of the droplet within the cupula as well as the amplitude of the rotation. Maximum displacement occurred just above the crista, while regions closer to the apex were displaced less. Third, cupula displacement was not equal for two different regions along the length of the crista. Droplets in the thin ventral region of the cupula had a mean amplitude of 6.6 μm for rotations with peak angular velocities of 200°/s. In contrast droplets in the region of transition between the thick and thin portions had amplitudes of only 4.1 μm for the same stimulus.We propose on the basis of these results that, during rotation, the cupula functionally behaves as a diaphragm with its greatest mechanical sensitivity adjacent to the crista. Hence, a minimal volume of the endolymph must be displaced to produce a given deflection of cilia. This diaphragm arrangement, along with the non-uniform thickness of the cupula and the profile of the endolymph flow through the canal, suggests a graded response along the length of the crista. The cupula may thus behave as a primary information filter which ‘pre-processes’ and separates rotational information (related to angular velocity and angular acceleration) through a ‘vestibular place phenomenon’.     

豚鼠颞骨显微解剖学研究

目的　准确定位豚鼠中、内耳结构。方法　对 15只正常健康成年豚鼠的中耳、内耳进行显微解剖 ,对颞骨标本标志结构放大 0 6 1倍并照相。结果　在豚鼠的颞骨标本上准确定位出下列中耳结构 :鼓膜、听骨链、卵圆窗、圆窗、咽圆窗鼓管鼓口、面神经等 ;内耳结构 :耳蜗、三个半规管、椭圆囊、球囊、乙状窦、内听道、内淋巴囊裂、前庭导水管口、蜗水管口等。结论　豚鼠颞骨结构与人体颞骨结构基本一致 ,但亦有区别 ,此项研究工作可以指导和帮助利用豚鼠作耳科研究的工作者准确定位中耳、内耳结构     

OC29 is preferentially expressed in the presumptive sensory organ region of the otocyst.

The mammalian inner ear derives from the otocyst. Molecular mechanisms underlying inner ear development are largely unknown. We have isolated a secreted molecule, OC29, from a rat otocyst cDNA library by the signal sequence trap method. OC29 was revealed to be a rat homologue of human WFIKKN. OC29 is preferentially expressed in the developing inner ear and the dorsal neural tube. In the inner ear, the expression of OC29 is first detectable at embryonic day 11.5 (E11.5), broadly in the dorsolateral region of the otocyst, which gives rise to the vestibular organ. At E12.5, the expression of OC29 becomes restricted to the presumptive sensory region, mainly to the BMP4-positive presumptive cristae, and expression becomes reduced at later stages. These results suggest that OC29 may have a role in the early development of the inner ear sensory organ, particularly in the formation of the cristae of the semicircular canals.     

Evolutionary changes in the cochlea and labyrinth: Solving the problem of sound transmission to the balance organs of the inner ear

This review article examines the evolutionary adaptations in the vertebrate inner ear that allow selective activation of auditory or vestibular hair cells, although both are housed in the same bony capsule. The problem of separating acoustic stimuli from the vestibular end organs in the inner ear has recently reemerged with the recognition of clinical conditions such as superior canal dehiscence syndrome and enlarged vestibular aqueduct syndrome. In these syndromes, anatomical defects in the otic capsule alter the functional separation of auditory and vestibular stimuli and lead to pathological activation of vestibular reflexes in response to sound. This review demonstrates that while the pars superior of the labyrinth (utricle and semicircular canals) has remained fairly constant throughout evolution, the pars inferior (saccule and other otolith, macular, and auditory end organs) has seen considerable change as many adaptations were made for the development of auditory function. Among these were a relatively rigid membranous labyrinth wall, a variably rigid otic capsule, immersion of the membranous labyrinth in perilymph, a perilymphatic duct to channel acoustic pressure changes away from the vestibular organs, and different operating frequencies for vestibular versus auditory epithelia. Even in normal human ears, acoustic sensitivity of the labyrinth to loud clicks or tones is retained enough to be measured in a standard clinical test, the vestibular-evoked myogenic potential test.     

Ontogenetic Variation in the Bony Labyrinth of Monodelphis domestica (Mammalia: Marsupialia) Following Ossification of the Inner Ear Cavities

Ontogeny, or the development of an individual from conception to death, is a major source of variation in vertebrate morphology. All anatomical systems are affected by ontogeny, and knowledge of the ontogenetic history of these systems is important to understand when formulating biological interpretations of evolutionary history and physiology. The present study is focused on how variation affects the bony labyrinth across a growth series of an extant mammal after ossification of the inner ear chambers. Digital endocasts of the bony labyrinth were constructed using CT data across an ontogenetic sequence of Monodelphis domestica, an important experimental animal. Various aspects of the labyrinth were measured, including angles between the semicircular canals, number of turns of the cochlea, volumes of inner ear constituents, as well as linear dimensions of semicircular canals. There is a strong correlation between skull length and age, but from 27 days after birth onward, there is no correlation with age among most of the inner ear measurements. Exceptions are the height of the arc of the lateral semicircular canal, the angular deviation of the lateral canal from planarity, the length of the slender portion of the posterior semicircular canal, and the length of the canaliculus cochleae. Adult dimensions of several of the inner ear structures, such as the arcs of the semicircular canals, are achieved before the inner ear is functional, and the non‐ontogenetic variation in the bony labyrinth serves as an important source for behavioral, physiological, and possibly phylogenetic information. Anat Rec, 2010. © 2010 Wiley‐Liss, Inc.