人工晶体植入前后视觉诱发电位的临床分析

目的:(1)探讨白内障囊外摘除术前术后及人工晶体植入术后视觉诱发电位幅值及潜时变化特征;(2)探讨白内障囊外摘除术术前P—VEP,F—VEP,F—ERG联合预测的必要性。方法:采用重庆泰克医电仪器公司产TEC—100C视觉电生理仪。对白内障患者实行分组测量。术前均测F—ERG,P—VEP,部分病例增测F—VEP。结果:114例术前F—ERG正常,P—VEP测量其P_(100)波幅值潜时均异常:P_(100)波幅值降低,潜时延长,术后及人工晶体植入后幅值,潜时都有所改善,而并发性白内障,代谢性白内障变化不明显。结论:据视觉诱发电位的变化,老年性白内障组,外伤性白内障组术后应及时装入人工晶体,并发性白内障组,代谢性白内障组装入人工晶体临床意义不大。术前联合测试(VEP ERG)对视力预后、以及眼底病变的定量诊断意义重大。     

糖尿病大鼠视网膜基因表达谱差异的初步分析

目的 建立大鼠正常视网膜和糖尿病8周视网膜基因表达谱，比较两者差异，初步分析糖尿病视网膜病变的相关基因。方法 通过限制片段差异显示 PCR（ restriction fragments differential display-PCR，RFDD-PCR）获得正常大鼠视网膜及8周糖尿病大鼠视网膜组织转录组片段。应用Fraent Analysis等软件，对差异片段进行生物信息学分析，初步确定糖尿病视网膜病变相关基因／表达序列标签（ expression sequence tag, Ksr）。结果 获得有意义的片段共3639个，有差异的片段840个，占表达数的23．08％。其中包括5个视觉传导相关基因，13个兴奋性神经递质受体基因和3个抑制性神经递质受体基因。糖尿病8周大鼠视网膜Rhodopsin kinase,β-arrestin,Phosducin, rod photoreceptor cGMP-gated channel 和 Rpe65的表达下调，离子型谷氨酸受体iGluR1-4下调，代谢性谷氨酸受体及γ-氨基丁酸受体各亚型则普遍上调，而甘氨酸受体表达无变化。结论 糖尿病8周大鼠神经视网膜已受到累及，其基因表达模式的改变，可能与糖尿病早期视功能损害有关。     

Localization of NPY-immunoreactivity in the cat's visual cortex

Summary Using a polyclonal antiserum against neuropeptide Y (NPY; J.M. Allen et al. 1983a) immunohistochemistry was carried out using the PAP method. Neurones displaying NPY-like immunoreactivity are seen mainly in cortical layers V/ VI, adjacent white matter and corona radiata. Only few neurones occur in superficial layers II/III. Neurones are multipolar to bitufted with spineless dendrites; somata are either round (layers V, II/III) or spindle-like (layer VI, white matter) with diameters between 16 and 20 m. Axones were identified by their initial smoother profiles, which are smaller in diameter than principal dendrites, by their typical branching pattern and the occurrence of terminal portions. It was found, that the degree of axonal ramification in proximal parts of axones is rather poor. Most NPY-neurones seem to project intracortically or even locally, except neurones in layers VI and the white matter. The latter neurones have ascending axonal branches terminating in layer VI and V, thus contributing to the dense NPY-plexus in these layers, whereas some layer VI neurones have axonal branches descending into the white matter. The axonal plexus in upper cortical layers is most probably fed by the ascending axones of layer V neurones, passing layer IVc in a strictly vertical direction. Fine smooth fibers of unknown origin which ascend from the white matter in a vertical direction through the grey matter also contribute to the plexus in layer II/III. In semithin sectioned material three terminal types were identified. Firstly, en passant boutons on immunnegative pyramidal neurones, secondly, perisomatically arranged, basket-like terminals, bending around unstained non-pyramidal neurones, and thirdly, about 60 m long vertically oriented rows of boutons exclusively on apical dendrites of layer II/III pyramidal neurones. Due to the unconspicious axonal pattern and the frequently observed basket-like terminal form, we conclude that most NPY-ir neurones can be regarded as a class of unspecific local field basket cells; the origin of the vertically arranged bouton rows has been yet to determined.     

Separate training of hemispheres to perform visual discrimination in conditions of blocking of interhemisphere transmission by masking

Subjects were trained to discriminate three figures presented in the left field of vision and three other figures presented in the right field of vision. In these conditions, the two hemispheres usually show identical learning to discriminate the sets of stimuli because the hemispheres in healthy humans can exchange information. In the present study, training was performed in conditions in which, during presentation of stimuli, the opposite visual hemifield was covered by a mask. After training, the recognition of all six figures was compared by presenting them to the left and right visual fields. Each hemisphere recognized figures presented to the cognate hemifield but completely or very nearly failed to recognize figures learned by the other hemisphere. The mask would thus appear to block (completely or partially) the transmission of information from one hemisphere to the other. Thus, it was possible to train the hemispheres separately to recognize different sets of images in healthy subjects.Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 89, No. 10, pp. 1177–1183, October, 2003.     

Reflection of an Orienting Reflex in the Phases of Evoked Potentials in the Rabbit Visual Cortex and Hippocampus during Substitution of Stimulus Intensity

Experiments on conscious rabbits were performed using the oddball paradigm, in which a rare (deviant) and common (standard) stimuli were of the same color but different intensities. Deviant stimuli were of lesser intensity. Recordings were made of evoked potentials induced by series of uniform deviant stimuli (without using standard stimuli), which were presented at the beginning and end of stimulation. Visual evoked potentials recorded in response to deviant stimuli in the visual cortex and hippocampus showed increases in the amplitudes of phases, shifted towards positivity as compared with responses to standard stimuli and uniform deviant stimuli at the beginning and end of stimulus blocks. Significant changes affected phases P1 and P2 of visual evoked potentials in the cortex and phases P1, N1, and P2 in the hippocampus. The most significant increase in evoked potentials in the cortex was seen for the P2 peak (P130). It is suggested that changes in responses to oddball-deviant stimuli result from an orienting reflex to rare, unexpected stimuli and that the P2 (P130) peak in the cortex is associated with transmission of information regarding changes in the intensity of the light. The amplitude of this peak was shown to be decreased in responses to uniform deviant stimuli at the beginning and end of stimulus blocks. It was also demonstrated that the clearest and most contrasting changes in visual evoked potentials in responses to deviant and standard stimuli were seen with the smallest differences in intensity between these types of stimulus, this reflecting increases in the orienting reflex at threshold differences.     

枕叶梗塞的临床、CT与视觉诱发电位分析

本文对28例枕叶梗塞病人分别进行了头颅CT及视觉诱发电位检查,结合临床分析,结果表明,枕叶梗塞临床少见,容易误诊,需要头颅CT或诱发电位检查协助诊断,且电生理阳性率优于形态学改变,可以弥补CT检查手段的不足。     

精神分裂症病人大脑两半球功能整合的实验研究

目的：检查精神分裂症患者可能存在的大脑两半球功能整合缺陷。方法：对20名精神分裂症患者和20名正常对照者进行不同复杂度汉字“同-异”判断的半视野速示实验。结果：①“同”判断的正确反应时（895．4毫秒）显著长于“异”判断（767．0毫秒）（F=87．44，P〈0．001），“同”判断的正确反应百分数（62．70）也显著低于“异”判断（95．30）（F=74．32，P〈0．001），表明“同”判断明显难于“异”判断；②患者和正常者一样，“异”判断的正确反应时和正确反应百分数在左视野（右半球）呈现、右视野（左半球）呈现和两视野（两半球）同时呈现三种条件之问均未出现显著差异；③正常人的“同”判断在两视野（两半球）同时呈现条件的正确反应时（674．8～743．4毫秒）明显快于左视野（右半球）（795．4—820．5毫秒）（t=2．89～4．57，均P〈0．001）和右视野（左半球）（798．6—857．1毫秒）（t=2．99—4．51，均P〈0．001），而病人没有出现两视野（两半球）对“同”判断的这种优势效应；④两视野（两半球）同时呈现条件下正常人“同”判断的正确反应百分数（88．3～89．5）与“异”判断（94．5—95．4）没有显著差异，而病人“同”判断的正确反应百分数（69．4—74．1）仍明显低于“异”判断（94．4—96．5）（t=2．39—2．60，均P〈0．05）。结论：精神分裂症患者仅在相对较难的“同”判断任务加工中表现出大脑两半球的功能整合缺陷。     

Co-localization of calcitonin gene-related peptide-like immunoreactivity with substance P in cutaneous, vascular and visceral sensory neurons of guinea pigs

Calcitonin gene-related peptide (CGRP) has been immunohistochemically co-localized with substance P (SP) in capsaicin-sensitive, varicose axons supplying the skin, viscera and cardiovascular system of the guinea pig. After treatment with colchicine in vitro, 82% of SP neurons in the dorsal root ganglia contained CGRP-like immunoreactivity while 96% of CGRP neurons were immunoreactive for SP. Both CGRP- and SP-like immunoreactive material are transported peripherally and centrally from dorsal root ganglia. Thus, in tissues such as the gut where there are intrinsic nerves containing SP but lacking CGRP, CGRP-like immunoreactivity is a useful means of specifically labelling axons of most sensory neurons containing SP.     

Receptive field characteristics of neurones in striate cortex of newborn lambs and adult sheep

The properties of cells of the striate visual cortex (V1) have been studied in the normal adult sheep and in new-born lambs without visual experience, the majority of cells in the lamb are orientation specific, but 20% are non-oriented compared to only 3% cells in the adult. In the lamb there was little or no facilitation of binocularly-driven cells by simultaneous stimulation of both receptive fields. Cells which responded only to binocular stimulation of particular disparities ('obligate binocular' cells) were rarely encountered. In the adult, 15% of the sample were obligate binocular cells and a further 28% showed binocular facilitation. Simple and complex receptive fields were found in similar proportions in both new-born lambs and adult sheep. End-stopped cells comprised 17% of the sample in adults but only 2% in the lambs. Direction sensitive cells were found more frequently in the sheep (21% of cells) than in the lamb (4% of cells). It is concluded that facilitatory processes in binocular cells and inhibitory mechanisms generally, seem much less developed in the lamb.     

Eccentric visual acuity in patients with macular disease

A series of cards each containing a two dimensional array of identical Snellen "E's" was used to determine best eccentric visual acuity in patients with macular disease having Snellen visual acuity of 20/70 or worse. Each "full field E" card simultaneously presents the same letter to foveal and parafoveal areas. This test can therefore determine quickly if potentially useful vision is present in any area of the central visual field. In our study of 37 eyes, 70% demonstrated potential visual acuity at least two times better than visual acuity measured by conventional methods, and 20% demonstrated at least a fourfold improvement. This suggests that most patients with macular disease do not spontaneously employ their best remaining area of retina for fixation.