Second-order reversed phi.

In a first-order reversed-phi motion stimulus (Anstis, 1970), the black-white contrast of successive frames is reversed, and the direction of apparent motion may, under some conditions, appear to be reversed. It is demonstrated here that, for many classes of stimuli, this reversal is a mathematical property of the stimuli themselves, and the real problem is in perceiving forward motion, which involves the second- or third-order motion systems or both. Three classes of novel second-order reversed-phi stimuli (contrast, spatial frequency, and flicker modulation) that are invisible to first-order motion analysis were constructed. In these stimuli, the salient stimulus features move in the forward (feature displacement) direction, but the second-order motion energy model predicts motion in the reversed direction. In peripheral vision, for all stimulus types and all temporal frequencies, all the observers saw only the reversed-phi direction of motion. In central vision, the observers also perceived reversed motion at temporal frequencies above about 4 Hz, but they perceived movement in the forward direction at lower temporal frequencies. Since all of these stimuli are invisible to first-order motion, these results indicate that the second-order reversed-phi stimuli activate two subsequent competing motion mechanisms, both of which involve an initial stage of texture grabbing (spatiotemporal filtering, followed by fullwave rectification). The second-order motion system then applies a Reichardt detector (or equivalently, motion energy analysis) directly to this signal and arrives at the reversed-phi direction. The third-order system marks the location of features that differ from the background (the figure) in a salience map and computes motion in the forward direction from the changes in the spatiotemporal location of these marks. The second-order system's report of reversed movement dominates in peripheral vision and in central vision at higher temporal frequencies, because it has better spatial and temporal resolution than the third-order system, which has a cutoff frequency of 3-4 Hz (Lu & Sperling, 1995b). In central vision, below 3-4 Hz, the third-order system's report of resolvable forward movement of something salient (the figure) dominates the second-order system's report of texture contrast movement.     

Signaling Mechanisms Mediating BDNF Modulation of Synaptic Plasticity in the Hippocampus

Although recent studies indicate that brain-derived neurotrophic factor (BDNF) plays an important role in hippocampal synaptic plasticity, the underlying signaling mechanisms remain largely unknown. Here, we have characterized the signaling events that mediate the BDNF modulation of high-frequency synaptic transmission. Mitogen-associated protein kinase (MAPK), phosphotidylinositol-3 kinase (PI3K), and phospholipase C-γ (PLC-γ) are the three signaling pathways known to mediate neurotrophin signaling in other systems. In neonatal hippocampal slices, application of BDNF rapidly activated MAPK and PI3K but not PLC-γ. BDNF greatly attenuated synaptic fatigue at CA1 synapses induced by a train of high-frequency, tetanic stimulation (HFS). Inhibition of the MAPK and PI3K, but not PLC-γ, prevented the BDNF modulation of high-frequency synaptic transmission. Neurotrophin-3 (NT-3), a close relative of BDNF, did not activate MAPK or PI3K and had no effect on synaptic fatigue in the neonatal hippocampus. Neither forskolin, which activated MAPK but not PI3 kinase, nor ciliary neurotrophic factor (CNTF), which activated PI3K but not MAPK, affected HFS-induced synaptic fatigue. Treatment of the slices with forskolin together with CNTF still had no effect on synaptic fatigue. Thus, although the activation of MAPK and PI3K is required, the two together are not sufficient to mediate the BDNF effect. Inhibition of new protein synthesis by anisomycin or cycloheximide did not prevent the BDNF effect. These data suggest that BDNF modulation of high-frequency transmission is independent of protein synthesis but requires MAPK and PI3K and yet another signaling pathway to act together in the hippocampus.     

关于健康社会性格的跨文化研究

社会性格作为国民素质的重要组成,其健康程度将直接影响精神文明建设的成效。本研究发现,当代人健康社会性格体系由五个因素构成,分别是：进取心、道德感、安定感、领导性与家庭性,为进一步深入探究,本研究采用跨文化方式,将日韩、欧美的参照样本与当代中国人进行比较研究,发现性别与国别因素对于五个因素中的若干项具有显著性影响,体现出跨文化差异性。本研究对于成功塑造跨世纪中国人健康社会性格将具有积极的理论与实践意义。     

8─11个月婴儿迂回行为发展特点与学习能力的研究

采用程序标准化的婴儿迂回行为测验,探讨了２４４名８─１１个月婴儿的迂回行为发展特点及学习能力。结果表明：（１）８─１１个月婴儿的迂回行为水平表现出随婴儿月龄的增长而提高的趋势。（２）８─１１个月的婴儿具有从反复尝试中学会迂回行为的可能性,其中９、１０个月婴儿的学习可能性较大,而８个月婴儿的学习可能性较小。（３）８──１１个月婴儿的学习速度随月龄增大而提高     

试论宗教与哲学的关系

宗教与哲学在内容和形式上是最具普遍性的观念形态,都具有世界观和人生观的性质,同属精神性的文化。从本质上讲,它们都是人对自然、社会和人生的一种认识、领悟和理解,试图解决的往往都是人们最为关注的人生中的根本性问题,如:生与死,祸与福,善与恶,今生与来世,现世与彼岸,世界上各种事物以至世界本身究竟如何形成,个人以至社会历史的命运为何种力量所支配和主宰等等,宗教和哲学都曾对此做出了自己的答案。正是由于关注的问题有着这种一致和重合的关系,宗教和哲学便在人类历史上结下了不解之缘。宗教里有哲学,哲学里也有宗教。宗教常使用哲学思维的方式和哲学的语言来论证其教义、确立其信仰;哲学则常把宗教视为神圣的教义信仰和哲学思考的对象,把它们放在理性审视台前进行考察和批判。     

完善我国ART机构伦理委员会结构和规模的构想

建立结构合理、规模适当的ART机构伦理委员会是有效发挥作用的基本要求和必备条件.针对存在的问题,根据委员会履行职责的需要,建议参照国际惯例,结合实际,制订我国ART机构伦理委员会结构和规模的标准或规范.     

中西方社会距离的研究综述

社会距离是人与人之间或群体与群体之间的理解与亲密的程度和等级,可分为主观距离、行为距离等。造成距离的原因很多,除了制度很均衡因素以外,还有社会地位差异、文化差异、空间隔离、生物差异等因素。     

汉语词汇产生中的义、音信息提取时间进程的ERP研究

摘 要 运用事件相关电位（ERP）技术考查了在汉语词汇产生过程中,语义提取和语音提取的时间进程。在实验过程中,给被试呈现一张图片,要求他们在小声进行图片命名之前,先基于语义信息（图上画的是物体还是动物）或语音信息（如图片名称是以字母s还是以y开头）完成一个双重选择任务。在一种情况下,反应手（左手或右手按键）由语义信息决定,是否反应（GO/NOGO）由语音信息决定;在另一种情况下,反应手由语音信息决定,是否反应由语义信息决定。结果发现,当是否反应由语义信息（动物/物体）决定时,N200的潜伏期是307ms;当是否反应由语音信息（如中文名称以S/Y开头）决定时,N200的潜伏期是447ms;两者之间存在显著的差异,即由语义信息引起的N200的潜伏期早于由语音信息引起的N200的潜伏期。结果表明,在汉语词汇产生过程中,语义提取先于语音提取。     

魏晋南北朝时期道教灵山崇拜论析

魏晋南北朝时期道教的灵山崇拜,源于上古原始宗教自然崇拜中的山神崇拜.道教从思想渊源上接受了山神崇拜,灵山崇拜随道教的传播更加深入人心.此外,道教灵山崇拜的盛行,还是洞天福地说的思想渊源.     

先验论证的逻辑分析

本文是对赵汀阳在《论先验论证》(《世界哲学》2005,3)中为先验论证所提供的逻辑模式的一个讨论和修正.通过对康德的先验演绎以及笛卡儿的我思论证进行逻辑分析,我们提出了一个以"归入条件"为基本特征的先验论证模式,并以这个模式为基础,对先验哲学的"演化历史"做了初步的总结,同时在最后也对先验哲学与"古代哲学"之间的差别得出了一个初步的结论.