脑功能光学成像技术及医学进展

本文较全面论述了目前发展中的脑功能光学成像技术:脑功能的内禀光学成像、神经元活动相关信号方法、光学相干层析成像、无损伤脑功能内禀光学成像等方法的原理、成像特性及相关最新医学研究进展.     

头部组织电阻抗成像研究进展

脑部疾病和脑功能活动期间常伴随脑组织电阻抗的变化,利用电阻抗成像技术可以对大脑疾病和脑功能活动进行临床诊断和监护。首先对人体头部组织阻抗测量技术的优缺点及其在头部组织阻抗成像上的应用前景进行简介,然后重点介绍了几种基于磁场测量的电阻抗成像方法,最后给出了目前头部阻抗成像研究存在的问题及该领域下一步的研究方向。     

小鼠颅骨视窗及其在光学活体脑成像研究中的应用

小鼠颅骨视窗作为一种活体光学脑成像辅助工具,以其原位表征、实时观察、长期活体脑成像等优势,成为脑部疾病及神经元突触生长等研究的重要手段之一。小鼠颅骨视窗不仅可以对颅骨下软脑膜血管及血管内红细胞流速、流态变化进行定量分析,在结合荧光标记物与光学显微镜后,还可以对脑部皮层下组织、神经细胞的变化进行清晰成像。过去数十年,科研人员利用小鼠颅骨视窗深入研究了偏头痛、阿尔兹海默症、神经突触等病理生理过程,并取得了大量突破性进展。同时,随着光学成像工具性能的提升,小鼠颅骨视窗的应用也得到了进一步拓展。本文主要介绍颅骨视窗的发展史、构建方法,结合荧光探针及光学成像方法的研究,全面总结了近年来小鼠颅骨视窗在光学脑成像研究中的应用,包括脑内重要生物分子成像、细胞成像、血管及血流成像、神经环路可塑性及神经功能成像、疾病发生机理及药物开发研究等,最后讨论了小鼠颅骨视窗在实际应用中面临的问题,并对其未来应用进行了展望。     

功能磁共振成像在认知神经科学中的应用

功能磁共振成像提供了一种无创的、在活体中间接检测神经活动的神经成像方式.功能磁共振成像技术在视觉、听觉以及记忆等认知神经科学领域取得了明显进展,其中包括通过任务或刺激模式下特定的实验设计,定位与这些认知过程相关的活动皮层区、发现某些疾病与功能丧失的联系,以及应用静息态功能磁共振成像对脑功能连接的探讨.本文还讨论了目前研...     

荧光素酶光学成像技术研究进展

活体动物体内光学成像技术的主要功能是追踪并检测标记细胞、微生物及分子在体内的活动和表达情况.该技术可以非侵入性地连续检测活体动物体内的生物学活动,其灵敏度高,使用方便、迅速,已被广泛应用于众多研究领域.就荧光素酶(Luc)光学成像技术的原理及应用进展作一综述.     

脑功能成像技术的研究

利用医学成像技术研究人类大脑功能是近年来发展最为迅速的领域之一。本文全面地综述了功能性磁共振成像术，正电子发射断层扫描述及其与脑电磁检测技术联合应用，开展的脑功能时成像的研究进展，     

句子加工脑机制功能磁共振研究进展

语言理解中,句子加工至关重要,其大脑机制是神经语言学比较关注的问题.近年来句法加工的脑成像研究大量涌现.本文对目前该领域的研究,以及汉语句子加工的最新进展进行了归纳与总结.     

脑功能成像技术的研究

利用医学成像技术研究人类大脑功能是近年来发展最为迅速的领域之一。本文全面地综述了功能性磁共振成像术（ＦＭＲＩ）、正电子发射断层扫描术（ＰＥＴ）及其与脑电磁检测技术（ＥＥＴ、ＭＥＧ）联合应用，开展的脑功能实时成像的研究进展，同时就新的成像理论及方法进行了论述，并指明脑功能成像技术的研究将为探索人类的认知与思维活动带来新的前景     

痛觉的脑成像研究进展

痛觉是日常生活中最重要的感觉之一,痛觉的机理非常复杂.随着20世纪90年代各种脑成像技术的成熟,现在人们对于大脑的痛觉处理过程有了更好的理解.综述了痛觉脑成像的研究方法,包括电生理技术和脑功能成像技术,重点关注了这些技术在痛觉研究方面的相关成果.指出了解剖学上的痛觉处理机制.并分析了目前痛觉脑功能成像研究存在的缺陷和不足.     

脑内源性光学成像中的图像增强处理

脑内源信号光学成像是一种二次成像技术,其信号微弱并带有皮层生理结构所决定的信号特征。选取有效的空间滤波方式能对图像的噪声进行抑制,使得微弱信号得以增强。本文针对脑内源性信号的光学成像,采用不同的线性与非线性空间滤波处理,并对噪声的抑制程度和图像细节保存程度进行讨论。结果显示非线性中值空域滤波对内源性光学图像去噪效果明显,并能保留丰富的细节特征,是适于脑内源性光学成像信号特点的图像增强技术。     

基于脑电的多模态神经功能成像新技术研究进展

神经功能成像能够实现活体脑结构与功能变化的无创(微创)检测。鉴于头皮脑电具有高时间分辨、便于操作、能直接反映大脑神经生理活动等优点,近年已逐步整合形成脑电-功能磁共振成像(EEG-fMRI)、脑电-近红外光谱(EEG-NIRS)、脑电-经颅聚焦超声(EEG-tFUS)等兼具高时空分辨优势的多模态神经功能成像新技术。从技术原理、技术特征及其在神经功能研究中的最新进展等方面,综述3种新模式的研究现状,论述存在问题与发展趋势,突出多模态神经功能成像新技术在促进脑科学发展中的意义。     

Seeing right through you: applications of optical imaging to the study of the human brain

A new set of techniques allows for the study of brain function by near-infrared light, exploiting two optical phenomena: Changes in light absorption are determined by changes in the concentration of substances like oxy- and deoxyhemoglobin, and changes in light scattering occur as a consequence of variations of properties of membranes and corpuscles in the neural tissue. Methods based on light absorption can be used to study hemodynamic changes in the brain, whereas those based on light scattering can be used to study neuronal activity and to provide anatomical information at a cellular and subcellular level. Three optical imaging approaches can be used to study living tissue: reflection, optical coherence tomography (OCT), and photon migration. These three approaches vary in their penetration (from less than a millimeter for reflection to up to 3-5 cm for photon migration) and spatial resolution (from a micron level for reflection and OCT to a millimeter and centimeter level for photon migration). This issue includes a collection of articles reviewing applications of these technologies to the study of brain and other bodily functions in humans.     

Optical coherence tomography imaging of the basal ganglia: feasibility and brief review

Optical coherence tomography (OCT) is a promising medical imaging technique that uses light to capture real-time cross-sectional images from biological tissues in micrometer resolution. Commercially available optical coherence tomography systems are employed in diverse applications, including art conservation and diagnostic medicine, notably in cardiology and ophthalmology. Application of this technology in the brain may enable distinction between white matter and gray matter, and obtainment of detailed images from within the encephalon. We present, herein, the in vivo implementation of OCT imaging in the rat brain striatum. For this, two male 60-day-old rats (Rattus norvegicus, Albinus variation, Wistar) were stereotactically implanted with guide cannulas into the striatum to guide a 2.7-French diameter high-definition OCT imaging catheter (Dragonfly™, St. Jude Medical, USA). Obtained images were compared with corresponding histologically stained sections to collect imaging samples. A brief analysis of OCT technology and its current applications is also reported, as well as intra-cerebral OCT feasibility on brain mapping during neurosurgical procedures.     

基于正则化方法的加权最小模估计在脑磁源成像中的应用

脑磁图 ( m agnetoencephalography,MEG)逆问题的研究 ,根据点源和分布源两种源模型 ,可分为偶极子定位和磁源成像两大类求逆方法。采用非参数的分布源模型 ,MEG逆问题转化为一个病态的欠定方程组的求解。本文系统地阐述了结合 Tikhonov正则技术的加权最小模磁源重建方法 ,着重介绍了深度归一化算法、低分辨率脑电磁断层成像技术、局部欠定系统解法、选择性最小模方法 ,此外还从广义的加权最小模估计角度对最大熵重建方法 ,融合其它脑功能成像技术的方法以及最大后验概率估计方法加以解释和分析。不同的磁源成像方法目的都是通过引入合适的约束条件 ,从算法公式本身及神经细胞活动的特性中加以修正 ,减少逆问题的不适定程度 ,因此均可认为是使用正则方法来约束解空间 ,从而获得与测量磁场数据相拟合的并具有神经生理学和解剖学意义下的最合理的解。基于正则化技术的加权最小模估计是 MEG逆问题研究中最早开展、并已被广泛应用的磁源分布图像重建方法 ,本文给出了一个较为完整的理论发展框架     

非人灵长类动物超高场磁共振脑成像技术进展

非人类灵长类动物是神经科学研究中的重要动物模型,可以兼容多种侵入式和非侵入式神经信号探测和神经活动调控方法.结合侵入式和非侵入式方法的非人灵长类动物的神经科学研究,有助于将大量基于动物模型的基础研究成果进行临床转化.其中磁共振脑成像技术是目前最主要的非侵入式大脑神经信号探测手段.非人灵长类动物磁共振脑成像研究,对于深入...     

Neural fibrolipoma of the superficial peroneal nerve in the ankle: a case report with immunohistochemical analysis

This report presents a case of neural fibrolipoma arising from the superficial peroneal nerve in the ankle. A 28-year-old woman was referred with a soft tissue mass in the anterior aspect of the right ankle, which had been gradually enlarging for the past 10 years. Magnetic resonance imaging showed a mass lesion, measuring approximately 8 x 3 x 2 cm, with high to partially low signal intensity on both T1- and T2-weighted images. A band of low signal intensity within the lesion, which is indicative of coexistence with the tumor and the superficial peroneal nerve, could be detected on both T1- and T2-weighted images. The patient underwent an excisional biopsy. The specimen microscopically consisted of nerve bundles and fibro-fatty proliferation with abundant collagen fibers. Immunoreactivity for CD34 antigen antibody was detected in fibrous spindle cells. This is the first report to present an immunohistochemical profile of neural fibrolipoma. Neural fibrolipoma should be considered as a differential diagnosis when a lipomatous lesion is encountered in the foot or ankle as well as in the upper extremities.     

Neural activity and the dynamics of central nervous system development

Recent imaging studies show that the formation of neural connections in the central nervous system is a highly dynamic process. The iterative formation and elimination of synapses and neuronal branches result in the formation of a much larger number of trial connections than is maintained in the mature brain. Neural activity modulates development through biasing this process of formation and elimination, promoting the formation and stabilization of appropriate synaptic connections on the basis of functional activity patterns.     

Hoxb1 functions in both motoneurons and in tissues of the periphery to establish and maintain the proper neuronal circuitry

Formation of neuronal circuits in the head requires the coordinated development of neurons within the central nervous system (CNS) and neural crest-derived peripheral target tissues. Hoxb1, which is expressed throughout rhombomere 4 (r4), has been shown to be required for the specification of facial branchiomotor neuron progenitors that are programmed to innervate the muscles of facial expression. In this study, we have uncovered additional roles for Hoxb1-expressing cells in the formation and maintenance of the VIIth cranial nerve circuitry. By conditionally deleting the Hoxb1 locus in neural crest, we demonstrate that Hoxb1 is also required in r4-derived neural crest to facilitate and maintain formation of the VIIth nerve circuitry. Genetic lineage analysis revealed that a significant population of r4-derived neural crest is fated to generate glia that myelinate the VIIth cranial nerve. Neural crest cultures show that the absence of Hoxb1 function does not appear to affect overall glial progenitor specification, suggesting that a later glial function is critical for maintenance of the VIIth nerve. Taken together, these results suggest that the molecular program governing the development and maintenance of the VIIth cranial nerve is dependent upon Hoxb1, both in the neural crest-derived glia and in the facial branchiomotor neurons.     

Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury.