脑光学成像对眼优势柱及其可塑性的研究进展

视觉发育的关键期，单眼视觉剥夺产生眼优势柱移动，其可塑性机制的认识目前尚不明确，有关研究将为弱视的康复奠定基础。脑光学成像为眼优势柱的功能解剖和电生理的深入研究提供了较为有效的方法。综述脑光学成像的方法，眼优势柱的可塑性，以及眼优势柱与方位优势柱的光学特征、相互关系等。     

运动训练对大鼠脑可塑性影响的研究进展

脑可塑性是指大脑在结构和功能上有修改自身以适应改变了的环境的能力。神经系统结构和功能的可塑性是神经系统的重要特性。这个过程受很多因素的影响。动物实验证明了饮食和行为控制、复杂环境、运动、过去习得的经验、脑损伤、学习、感觉刺激（光、听觉）．物理刺激等均会使成年动物的神经元或突触的功能和形态出现各种代偿性变化．此变化过程包括了形态学，电生理学和生物化学（即一些相关蛋白、神经因子的基因表达）等几方面。其中运动是中枢神经系统最有效的刺激形式，所有运动都可向中枢神经系统提供感觉、运动和反射性传入，运动对大脑的功能重组和代偿起着重要作用。在动物实验中多采用大鼠来进行中枢神经系统可塑性的研究。下面将近几年来动物实验中运动训练对大鼠脑可塑性影响研究新进展作如下简要综述。     

评价脑功能和脑的可塑性的综合技术

脑的可塑性研究显示,无论健康状态还是损伤以后,无论儿童、成人还是老年人,脑在外界环境输入影响下均有很强的可塑性。了解和评价其可塑性机制是寻求高效治疗措施、促进恢复的重要基础。现回顾CNS可塑性机制以及评价脑功能和脑可塑性的无创的综合技术。     

身体活动对大脑可塑性影响的研究进展

大脑可塑性是大脑随着环境和经验变化而发生神经结构和功能变化的能力。运动可以改善大脑功能,影响大脑可塑性。本文综述有氧运动、抗阻运动,平衡运动和太极拳等对不同脑区的影响以及相关机制。     

弱视视皮层可塑性的分子生物学机制研究进展

弱视是视觉发育敏感期异常视觉经验所导致的以空间视力损害为特征的一组视力不良综合症[1].视皮层在发育的过程中存在"敏感期",具有可塑性,而弱视治疗的依据就在于视觉发育敏感期内可塑性的存在[2],现在对弱视的视皮层可塑性机制研究已经上升到了分子水平,现将近10年视皮层可塑性的分子生物学研究文献综述如下.     

关于疼痛的脑成像研究进展

人类疼痛的脑成像研究可分为两类：一是脑地形图研究，即脑电图（ＥＥＧ）和脑磁图（ＭＥＧ）及其诱发改变，包括事件相关电位（ＥＲＰ）和诱发磁场（ＭＥＦ）的地形图；二是脑成像研究，即正电子发射断层扫描术（ＰＥＴ）和功能磁共振成像（ｆＭＲＩ）断层摄影术。其主要...     

低强度经颅超声影响大脑可塑性的研究进展

低强度经颅超声（LITUS）是近年来新兴的一种非侵入性脑刺激技术,通过超声波的机械力作用调节大脑皮质的电活动,从而对皮质兴奋性产生增强或抑制作用。LITUS不仅能作用于皮质,还能聚焦于大脑深部组织,具有较高的空间分辨率。LITUS可在导航下精确定位刺激靶区,且对靶区周围的其他组织不产生影响。目前,LITUS的神经调控作用和安全性已在动物实验中得到证实,但在临床试验方面仍处于起步阶段。本文就LITUS影响神经可塑性的可能机制、动物研究和临床研究进展及治疗安全性作一综述。     

影响皮质可塑性因素的研究

虽然在上世纪 3 0年代BetheA即提出脑的可塑性理论 ,但在 15 -3 0年前 ,学术界的普遍观点还是脑的功能损伤是不能恢复、再生和修复的。目前 ,脑的可塑性当今己为许多现代化手段 (PET、fMRI、TMS等 )和临床实验所证实。脑的功能恢复 ,即脑的功能重组和可塑性 ,在脑血管病和外伤性脑损伤中研究得最多。现就影响可塑性的因素 ,如年龄、神经营养因子、神经干细胞神经移植、神经调节剂、激素、环境与药物干预等介绍如下。1年龄年龄对脑损伤的恢复有影响 ,即所谓“Kennard”原理 :脑在生命早期受到伤害与成熟个体同样伤害相比 ,损伤要少得多[…     

造血干细胞的可塑性研究进展

近年来,关于成体干细胞(adult stemcells)可塑性(plasticity)的研究在学术界引起了极大轰动.作为研究最早和最为深入的干细胞,造血干细胞(hemotopoieticstem cells,HSC)首当其冲,成为这类研究的代表.我们就HSC可塑性研究方面的进展作一综述.……     

Optical imaging in cat area 18: strabismus does not enhance the segregation of ocular dominance domains

While early-onset strabismus leads to clearly segregated domains of the left and the right eye in cat primary visual cortex (area 17), far less is known about experience-dependent plasticity of ocular dominance in area 18. We therefore used optical imaging of intrinsic signals to analyze the influence of strabismus on cortical maps in cat area 18. Monocular visual stimulation of the left and right eye with moving square wave gratings of four different orientations induced patchy activity maps. Unlike our previous observations in cat area 17, the monocular activity maps in area 18 of strabismic cats were rather similar so that functional ocular dominance domains were not clearly segregated. Imaging of the 17/18 border region confirmed this observation and revealed a sudden change in the segregation of the left and right eye domains across the border. Our results demonstrate that modified visual input can have different consequences for different visual areas: while the decorrelation of activity between the two eyes (as induced by strabismus) clearly enhances the segregation of ocular dominance domains in cat area 17, area 18 does not show this effect although electrophysiological studies have confirmed that the percentage of binocularly driven neurons is as reduced as in area 17.     

Robust detection of ocular dominance columns in humans using Hahn Spin Echo BOLD functional MRI at 7 Tesla

Cells in the mammalian brain tend to be grouped together according to their afferent and efferent connectivity, as well as their physiological properties. The columnar structures of neocortex are prominent examples of such modular organization, and have been studied extensively in anatomical and physiological experiments in rats, cats and monkeys. The importance of noninvasive study of such structures, in particular in human subjects, cannot be overemphasized. Not surprisingly, therefore, many attempts were made to map cortical columns using functional magnetic resonance imaging (fMRI). Yet, the robustness, repeatability, and generality of the hitherto used fMRI methodologies have been a subject of intensive debate. Using differential mapping in a high magnetic field magnet (7 T), we demonstrate here the ability of Hahn Spin-Echo (HSE) BOLD to map the ocular dominance columns (ODCs) of the human visual cortex reproducibly over several days with a high degree of accuracy, relative to expected spatial patterns from post-mortem data. On the other hand, the conventional Gradient-Echo (GE) blood oxygen level dependent (BOLD) signal in some cases failed to resolve ODCs uniformly across the selected gray matter region, due to the presence of non-specific signals. HSE signals uniformly resolved the ODC patterns, providing a more generalized mapping methodology (i.e. one that does not require adjusting experimental approaches based on prior knowledge or assumptions about functional organization and vascular structure in order to avoid confounding large vessel effects) to map unknown columnar systems in the human brain, potentially paving the way both for the study of the functional architecture of human sensory cortices, and of brain modules underlying specific cognitive processes.     

少年儿童眼外伤相关因素的分析及对策

眼外伤是眼科临床上的一种常见病、多发病，特别在眼科急诊中占有很大的比重，是视力损害的主要原因，是单眼失明的首要原因。近年来眼外伤有明显的增长趋势，尤以少年儿童为多。对少年儿童而言眼外伤可以造成其人生轨迹的转折而影响其一生，应该引起全社会对眼外伤的重视和关注。故对我院眼科2002年4月-2004年11月共收治的101例少年儿童眼外伤进行统计分析，以期望从中找出预防少年儿童眼外伤的措施和方向。     

移植视网膜神经元的发育规律及其再生和可塑性意义

背景近年的移植实验表明,移植视网膜内能合成相关的神经活性物质,但移植视网膜内神经活性物质阳性神经元的生长发育情况尚不清楚. 目的观察移植视网膜神经元的分化、发育,神经活性物质的生物合成及其与周围环境、视觉中枢的联系,以探讨神经组织的发育规律及其再生和可塑性.设计以动物为研究对象,观察对比研究.单位两所大学的组胚教研室.材料实验于2002-08/2003-03在广州医学院实验动物中心完成.选择健康SD大鼠96只,雌雄不限.干预用胚14 d SD大鼠视网膜移植至P1大鼠中脑左侧上、下丘间,同时摘除P1鼠右眼,术后第9天移植视网膜的发育时间与生后第1天正常视网膜相当,记为TP1,余类推,应用组织化学方法显示神经元的发育和分化.主要观察指标移植视网膜和移植视网膜神经元的发育及形态观察.结果移植视网膜具有正常视网膜的各层结构和相似的生长发育规律,并能合成相关的神经活性物质.移植视网膜内一氧化氮合酶阳性神经元开始出现于TP4,TP12时阳性神经元数量达到高峰,TP22后阳性神经元数目维持在较低的水平.结论胚胎视网膜脑内移植后能存活且保持原有的生长发育规律,具有正常视网膜一样的组织结构特征.     

少年儿童眼外伤相关因素的分析及对策

眼外伤是眼科临床上的一种常见病、多发病,特别在眼科急诊中占有很大的比重,是视力损害的主要原因,是单眼失明的首要原因[1]。近年来眼外伤有明显的增长趋势,尤以少年儿童为多。对少年儿童而言眼外伤可以造成其人生轨迹的转折而影响其一生,应该引起全社会对眼外伤的重视和关注。故对我院眼科2002年4月—2004年11月共收治的101例少年儿童眼外伤进行统计分析,以期望从中找出预防少年儿童眼外伤的措施和方向。1临床资料101例眼外伤病例中男79例,女22例,男女比例约为3.6∶1;家居农村的69例,占居住环境分布总数68.32%;住院时间最长60d,最短2d,平…     

Purification of recombinant adeno-associated virus vectors by column chromatography and its performance in vivo

Recombinant adeno-associated virus (AAV) holds much promise for human gene therapy. While evidence indicates that AAV mediates long-term gene transfer in several different tissues, difficulty in preparing and purifying this viral vector in large quantities remains a major obstacle for evaluating AAV vectors in clinical trials. The current method of purification, based on sedimentation through cesium chloride, is not scaleable and yields product of insufficient quality. In this article we report a new technique for purifying AAV, using a fully closed two-column chromatography system. Yields of AAV vectors purified by this method are high, potency is increased, and the purity of column-purified preparations is substantially improved. We previously reported a novel method to generate AAV based on an AAV Rep/Cap-containing cell line (B50) and an Ad-AAV hybrid virus, which is amenable to scale-up in bioreactors. By combining the new, fully scaleable purification process we report here with the B50/hybrid production method, it would be feasible to prepare AAV vectors to the scale and purity required for clinical and potential commercial applications.     

对成体干细胞可塑性的新认识及其在再生医学中的意义

根据个体发育过程中出现的先后次序不同 ,干细胞可分为胚胎干细胞和成体干细胞。胚胎干细胞出现在胚胎发育的胚囊内层 ,高水平表达端粒酶。1981年ＭａｒｔｉｎＥｖａｎｓ首次从小鼠胚囊中分离出小鼠胚胎干细胞 ,后被证实具有自我复制能力 ,且可分化为诸如神经细胞、心肌细胞、肝细胞、β 胰岛细胞、骨细胞、造血细胞等 2 0 0多种组织器官的原始细胞。胚胎干细胞继续分化 ,形成组织定向的多潜能干细胞 ,如多潜能造血干细胞可形成各种血细胞 ,多潜能皮肤干细胞可形成各种类型的皮肤细胞。在胎儿、儿童和成人组织中存在的这类多潜能干细胞统称…     

Nucleotides in ocular secretions: their role in ocular physiology

The eye is the sense organ that permits the detection of light owing to the existence of a sophisticated neuronal array, called the retina, which is responsive to photons. The correct functioning of this complex system requires the coordination of several intraocular structures that ultimately permit the perfect focusing of images on the neural retina. Light has to pass through different media: the tear, the cornea, aqueous humour, lens, and vitreous humour before it reaches the retina. Moreover, the composition and structure of some of these media can change due to several physiological mechanisms. Nucleotides are active components of the humours bathing relevant ocular structures. The tear contains nucleotides and dinucleotides that control the process of tearing, wound healing and protects of superficial infections. In the inner eye, the aqueous humour also presents a collection of mono and dinucleotides that affect pupil contraction, aqueous humour production and accommodation. Behind the lens and between this structure and the retina the vitreous humour can modify the physiology of the retinal cells, mostly the ganglion cells. By investigating the actions of nucleotides and dinucleotide present in the ocular humours we will be able not only to understand the functioning of the ocular structures but also to develop new pharmacological therapies for pathologies such as dry eye, glaucoma or retinal detachment.     

Neural plasticity: Part 2. Postnatal maturation and function-induced plasticity

At birth, the central nervous system has completed most of its early stages of cell division, migration, and specialization. Much of the neural circuitry has been laid down. Neuroblasts are continuing to divide only in limited brain regions. Hence, at birth, most mammals have a nearly full complement of neurons. Nonetheless, the functional capabilities of the central nervous system of the newborn have little resemblance to those of the adult. Postnatal maturation must proceed in the proper sequence and at the proper rate if central nervous system deficits in the adult are to be avoided. Many of the prenatal maturational phenomena described in the previous paper continue well into the postnatal period. The purpose of this paper is to describe some postnatal maturational mechanisms and to show, by selected examples, the important role that function and experience play in central nervous system development.