神经营养素在视觉中枢发育中的作用

神经营养素在发育的视觉系统中表达 ,并且能够以活动依赖的方式调节突触可塑性及神经元生长 ,在视觉系统发育中起重要作用。     

抑郁症患者视觉损伤的研究进展

视觉损伤在抑郁症患者中较为常见，抑郁症患者的视觉处理能力在各个阶段都受到了损害，目前研究集中在对比敏感度、视觉掩蔽、视觉注意、面部表情识别、运动视觉等方面。视觉加工障碍会导致正常感知觉的缺陷，因此无法正常激活奖赏通路，进而加重抑郁症患者的快感缺乏。文章就抑郁症视觉加工方面的损害情况及相关的脑机制进行综述，旨在为进一步的研究作参考。     

1000/人工视觉假体视觉映像信息处理模型

视觉映像的信息处理机制是人工视觉研究中最重要的基础工作和核心技术之一。本文在阐述人类视觉信息获取及处理原理的基础上,提出一种人工视觉映像信息处理模型。然后详细阐述这一模型在学习训练阶段和应用阶段的系统结构和关键技术。     

鞍区肿瘤的显微手术治疗中视觉功能保护

目的 探讨鞍区肿瘤患者视觉功能障碍的原因和手术切除过程中视觉功能的保护.方法 回顾性分析2001年1月至2010年10月手术治疗的74例鞍区肿瘤患者临床资料,包括手术入路及手术前后视觉功能状况等.结果 术后随访3月至2年,术前视觉功能正常的25例患者中,术后没有发现视觉功能下降;术前视觉功能障碍的49例患者中,术后视觉...     

神经营养在视觉中枢发育中的作用

神经营养素在发育的视觉系统中表达，并且能够以活动依赖的方式调节突触可塑性及神经元生长，在视觉系统发育中起重要作用。     

应用视觉诱发电位术中监测视觉功能的研究

目的评价视觉诱发电位(VEP)在切除累及视路病灶的手术中监护视觉功能方面的可行性和可靠性。方法回顾分析31例累及视路病变的患者的临床资料,全静脉麻醉后手术,用2.1Hz的闪光二极管刺激患者,通过头皮(29例)或皮层(2例)记录视觉诱发电位,分析术中诱发电位的变化与术后视觉功能变化的关系。结果 25例患者描记出清晰、可重复的波形;VEP异常或消失的患者有7例,术后视力下降2例,视野缺损加重6例;8例术中出现VEP波形的异常,予及时改变手术策略,避免对视路的进一步骚扰后,2min内波形渐趋正常,术后仅有1例出现视野缺损。结论视觉诱发电位是一种能够提供实时视觉功能监测的可靠方法,能及时发现视路损伤。     

视觉诱发电位在颅内肿瘤诊治中的应用

视觉诱发电位（Visual evoked potentials,VEP）通过监测视觉通路的生物电变化,已被广泛应用于临床评价神经系统及眼科系统病变的视觉功能状态。颅内脑肿瘤常通过直接侵袭或压迫视觉通路神经纤维,造成视觉传导功能的损害。VEP技术主要应用于评价颅内脑肿瘤的视觉功能状态,对脑肿瘤的早期筛选,鉴别视路不同部位肿瘤的位置,脑肿瘤的动态观察及脑肿瘤手术中监护等方面。     

中西方纯失读症在视觉词形加工机制上的差异

纯失读症是损害定位于阅读早期阶段即词形加工的功能障碍,症状单一且病变部位特殊,多累及视觉词形加工区域。文字阅读作为一种获得性高级神经功能,与文化密切相关,故比较中西方纯失读症的异同能够更加深入地了解视觉词形加工机制。中西方纯失读症具有不同临床表现,文字信号特征的差异性是根本原因,视觉词形加工区域的可塑性是神经生物学基础。中西方文字阅读均呈现左侧半球偏侧化特点,但汉语纯失读症的特殊现象可推测右侧大脑半球在汉语加工中的作用更为突出。中西方阅读的fMRI研究均提示视觉词形加工区域内部存在等级结构,对应于亚词汇加工的分级制度,但尚不足以解释汉语纯失读症中词长效应阙如等现象。汉字辨认可能更依赖于腹侧视觉通路即整字的加工。     

前额叶损伤患者的视-空间工作记忆改变

目的 探讨前额叶不同亚区损伤患者的视-空间工作记忆障碍.方法 将20例前额叶不同亚区损伤患者以及20名与其人口学资料相匹配的健康人作为被试,采用视觉面孔和视觉空间的延迟匹配任务对上述2组进行视-空间工作记忆测试.结果 与健康对照组(72.9%±6.1%)相比,前额叶腹侧(ventral prefrontal cortex,VPFC)损伤的患者视觉客体工作记忆的正确率(46.4%±11.4%)明显下降,差异有统计学意义(U=1.00,P<0.01);而前额叶背外侧(dorsolateral prefrontal cortex,DLPFC)损伤的患者在视觉客体(50.4%±15.1%)和视觉空间(72.6%±18.6%)工作记忆均有明显损伤,与对照组(72.9%±6.1%、89.4%±10.1%)比较差异均有统计学意义(U=-20.5、59.5,均P<0.01).对左、右前额叶损伤的2组患者进行分析,结果表明2组患者在视觉客体和空间工作记忆正确率的比较差异均无统计学意义.对前额叶亚区进行左右侧比较,2组VPFC患者在视觉客体和视觉空间工作记忆差异均无统计学意义;左侧DLPFC损伤组和右侧DLPFC损伤组在视觉客体工作记忆正确率和视觉面孔工作记忆正确率方面,差异均无统计学意义.结论 前额叶是工作记忆加工的重要脑区,其不仅参与了视觉客体的工作记忆加工过程,同时参与了视觉空间的工作记忆加工,而且对于前额叶不同亚区在视-空间工作记忆加工过程中还存在分离.     

光学相干断层成像术在中枢神经系统脱髓鞘疾病中的应用价值

光学相干断层成像术(optical coherence tomography,OCT)可客观清楚地显示视网膜结构变化,在眼科疾病诊疗中被广泛应用.视神经炎(optic neuritis,ON)是中枢神经系统脱髓鞘疾病的主要临床表现,可引起不同程度的视觉功能障碍.在临床工作中对视觉功能的评估方法 多样,各有利弊.现就OC...     

Denervation study of synapses of organ of corti of old world monkeys

Fine structural characteristics of synapses in the spiral organ of Corti were examined, with reference to differences between inner and outer haircell systems, and to location of neurons of origin of efferent axons. Surgical interruption of crossed olivocochlear bundle, of vestibular nerve, of facial nerve, and excision of superior cervical ganglia were used to determine the pathways of efferent axons. Interruption of the vestibular nerve near the brainstem results in degeneration of all efferent terminals on outer hair cells. Mid-line lesions at, and caudal to, the facial colliculus result in degeneration of about half of these efferent terminals. Efferent synaptic bulbs to the inner hair-cell system are small, of the order of one micron, and form type 2 junctions with afferent dendrites. They tend to have more large dense-core vesicles (about 80 nm) than the large efferent terminals of the outer hair-cell system, and appear to be the terminals of axons in the habenula perforata, which exhibit varicosities laden with large dense core vesicles. The varicosities are unaffected by excision of the superior cervical ganglia. So far as our material can reveal, it appears that the varicosities in the habenula perforata do not survive vestibular root interruption, nor do the efferent processes in the internal spiral bundle or at the base of inner hair cells. Most interestingly, the afferent processes of the inner hair-cell system, as identified for example by their relation to pre-synaptic bodies in the inner hair cells, are subject to a trans-synaptic reaction after severance of the vestibular root. They undergo a dramatic cytological transformation, characterized by increase of volume, engorgement with microtubules, microfilaments, microvesicles of various sizes, and clusters of lysosomes. Thus, both the efferent and afferent terminals of the inner hair-cell system show marked cytological differences from the corresponding terminals of the outer hair cell system.     

Mechanism of action of tubocurarine on nicotinic cholinoreceptors of neurons of the sympathetic ganglia of rats

Tubocurarine (Tc) effect on membrane currents elicited by acetylcholine (ACh) was studied in isolated superior cervical ganglion neurons of rat using patch-clamp method in the whole-cell recording mode. The "use-dependent" block of ACh current by Tc was revealed in the experiments with ACh applications, indicating that Tc blocked the channels opened by ACh. Mean lifetime of Tc-open channel complex, tau, was found to be 9.8 +/- 0.5 s (n = 7) at -50 mV and 20-24 degrees C. tau exponentially increased with membrane hyperpolarization (e-fold change in tau corresponded to the membrane potential shift by 61 mV). Inhibition of the ACh-induced current by Tc (3-30 microM/1) was completely abolished by membrane depolarization to the level of 80-100 mV. Inhibition of ACh-induced current was augmented at increased ACh doses. It is concluded that the open channel block produced by Tc is likely to be the only mechanism for Tc action on nicotinic acetylcholine receptors in superior cervical ganglion neurons of rat.     

The effect of age of onset of PD on risk of dementia

Background Dementia occurs in the majority of patients with Parkinson’s disease (PD). Late onset of PD has been reported to be associated with a higher risk for dementia. However, age at onset (AAO) and age at baseline assessment are often correlated. The aim of this study was to explore whether AAO of PD symptoms is a risk factor for dementia independent of the general effect of age. Methods Two community-based studies of PD in New York (n = 281) and Rogaland county, Norway (n = 227) and two population-based groups of healthy elderly from New York (n = 180) and Odense, Denmark (n = 2414) were followed prospectively for 3–4 years and assessed for dementia according to DSM-IIIR. All PD and control cases underwent neurological examination and were followed with neurological and neuropsychological assessments. We used Cox proportional hazards regression based on three different time scales to explore the effect of AAO of PD on risk of dementia, adjusting for age at baseline and other demographic and clinical variables. Findings In both PD groups and in the pooled analyses, there was a significant effect of age at baseline assessment on the time to develop dementia, but there was no effect of AAO independent of age itself. Consistent with these results, there was no increased relative effect of age on the time to develop dementia in PD cases compared with controls. Interpretation This study shows that it is the general effect of age, rather than AAO that is associated with incident dementia in subjects with PD. Received in revised form: 22 December 2005     

Limits of deinstitutionalization--perspectives of relatives of psychiatric patients

After a hopeful beginning, the social process of the reintegration of those with severe mental illness has come to a standstill. I am led to wonder whether "the community" really wants to live together with people suffering from severe mental illness, and if so, how closely? As long as the medical treatment of mental illness provided by the general practitioners is fundamentally deficient, as they are not able to prescribe the necessary interventions--such as out-patient psychiatric nursing, and service providers in the out-patient sector are content with offering increasingly intensive forms of care for the less seriously ill at the cost of the Social Welfare System--the reintegration of those with serious mental illness remains an illusion--which is mainly to the benefit of providers of residential care in homes and hostels.