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281.
Transgenic Brain-Derived Neurotrophic Factor Modulates a Developing Cerebellar Inhibitory Synapse 总被引:3,自引:0,他引:3
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Shaowen Bao Lu Chen Xiaoxi Qiao Richard F. Thompson 《Learning & memory (Cold Spring Harbor, N.Y.)》1999,6(3):276-283
Brain-derived neurotrophic factor (BDNF) has been shown to promote synapse formation and maturation in neurons of many brain regions, including inhibitory synapses. In the cerebellum, the Golgi cell-granule cell GABAergic synaptic responses undergo developmental transition from slow-decaying to fast-decaying kinetics, which parallels a developmental increase of GABAA receptor α6 subunit expression in the cerebellar granule cells. In culture, BDNF accelerates the expression of GABAA receptor α6 subunit expression in granule cells. Here we examined synaptic GABAA response kinetics in BDNF transgenic mice. The mutant mouse, which carries a BDNF transgene driven by a β-actin promoter, overexpresses BDNF (two- to fivefold increase compared with wild types) in all brain regions. Recordings of the spontaneous GABAA responses indicate that the decay time constant of the GABAergic responses decreases during early postnatal development; this transition is accelerated in the BDNF transgenic mouse. The amplitude of the spontaneous GABAA responses was also larger in the transgenic mouse than in the wild-type mouse. However, the frequency of the spontaneous GABAA responses were not different between the two groups. Our results suggest that BDNF may modulate GABAergic synapse maturation in the cerebellum. 相似文献
282.
爬行与婴儿共同注意能力的发展 总被引:2,自引:0,他引:2
本研究考察了8~11个月婴儿共同注意能力的发展趋势以及爬行与其发展的关系。结果表明:1)一岁以内的婴儿在共同注意时有仅跟视相同方向与准确定位他人注视点两种不同水平的表现,这两种表现具有不同的发展趋势;2)影响婴儿共同注意时仅跟视相同方向水平发展的主要因素是婴儿的年龄,爬行时间的效应不显著;3)对婴儿准确定位的发展而言,影响其发展的重要因素是婴儿的爬行而不是婴儿的年龄。 相似文献
283.
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 theforward (feature displacement) direction, but the second-order motion energy model predicts motion in thereversed 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 mech-anisms, 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 equiva-lently, 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 resolu-tion than the third-order system, which has a cutoff frequency of 3–4 Hz (Lu & Sperling, 1995b). In cen-tral 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. 相似文献
284.
《儿童认知能力诊断量表》的特点与分析 总被引:1,自引:0,他引:1
本文分析了《儿童认知能力诊断量表》的特点及其在鉴别和诊断学习不良儿童认知缺陷中的作用。该量表由三个分测验和七个项目组成。量表的常模取样于浙江省十个城市的333名1~3年级儿童。数据处理和分析的结果表明:(1)该量表能反映出小学儿童认知能力随年级增长的趋势;(2)重测信度表明量表具有一定的可靠性;(3)该量表有较好的鉴别效度,而且效度检验的结果说明了学习不良儿童在认知能力上的“多病源”特征。 相似文献
285.
石杉碱甲对动物行为和脑皮层电图的影响 总被引:2,自引:0,他引:2
石杉碱甲是我国首先从石杉科植物中提取出的一种新生物碱。它是胆碱酯酶抑制剂,它的作用和毒扁豆碱相似,但其毒性较小。本文观察了石杉碱甲对大鼠暗回避反应和家兔脑皮层电图的影响。其主要结果如下: 1 石杉碱甲可对抗东莨菪碱所致的记忆障碍,主要表现为石杉碱甲可使动物进入暗箱的潜伏期延长,并使暗回避反应的错误次数明显减少。 2.石杉碱甲能使家兔皮层区的脑电波均持续出现低振幅快波,并使海马区出现持续的且有规则的θ节律。脑皮层电图的结果表明,石杉碱甲和东莨菪碱相互不但有颉顽作用,而且,进一步证实了石杉碱甲对东莨菪碱的颉顽主要是通过中枢作用来调制的。 相似文献
286.
287.
Rolim L Zagalo-Cardoso JA Paúl C Sequeiros J Fleming M 《Journal of genetic counseling》2006,15(5):375-391
This study describes the construction of a self-response inventory to evaluate the perception of advantages and disadvantages of the Machado-Joseph disease presymptomatic testing, in 44 individuals at-risk for this disease. The results showed that the reliability of this inventory was satisfactory. Factor analysis revealed a bidimensional structure: perceived advantages (pros) and perceived disadvantages (cons) of presymptomatic testing. Social desirability was found unrelated to the total scores of our inventory. Additional correlation studies, with other scales, confirmed the convergent validity of the instrument. These results suggest adequate construct validity. This inventory thus seems to be a proper instrument to assess expectations involved in the decision-making process of Machado-Joseph disease presymptomatic testing. 相似文献
288.
NT-3 facilitates hippocampal plasticity and learning and memory by regulating neurogenesis 总被引:5,自引:0,他引:5
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Shimazu K Zhao M Sakata K Akbarian S Bates B Jaenisch R Lu B 《Learning & memory (Cold Spring Harbor, N.Y.)》2006,13(3):307-315
In the adult brain, the expression of NT-3 is largely confined to the hippocampal dentate gyrus (DG), an area exhibiting significant neurogenesis. Using a conditional mutant line in which the NT-3 gene is deleted in the brain, we investigated the role of NT-3 in adult neurogenesis, hippocampal plasticity, and memory. Bromodeoxyuridine (BrdU)-labeling experiments demonstrated that differentiation, rather than proliferation, of the neuronal precursor cells (NPCs) was significantly impaired in DG lacking NT-3. Triple labeling for BrdU, the neuronal marker NeuN, and the glial marker GFAP indicated that NT-3 affects the number of newly differentiated neurons, but not glia, in DG. Field recordings revealed a selective impairment in long-term potentiation (LTP) in the lateral, but not medial perforant path-granule neuron synapses. In parallel, the NT-3 mutant mice exhibited deficits in spatial memory tasks. In addition to identifying a novel role for NT-3 in adult NPC differentiation in vivo, our study provides a potential link between neurogenesis, dentate LTP, and spatial memory. 相似文献
289.
In the Western studies of the texts of Mozi, three distinctive views have surfaced in the past few decades: (1) Mozi is inconsistent because he seems to have been committed to both a Utilitarian standard and a divine command theory; (2) Mozi is a divine command theorist who argues that it is right to benefit the world because it is the will of heaven; and (3) Mozi is a utilitarian thinker who has based morality on the criterion of whether actions benefit the world. In this paper, I will argue that the whole debate about whether Mozi is a divine command theorist or a utilitarian is misguided, because it is based on an incorrect understanding of the fundamental cultural perspective associated with the notion of Tian. An adequate understanding of the notion of Tian will reveal its fundamental difference from the Western notion of heaven. Such an understanding will enable us to put Mozi's moral philosophy in the ancient Chinese perspective in which a tension and potential conflict between ‘the will of heaven’ and ‘the benefit of the world’ simply cannot arise. 相似文献
290.