共查询到20条相似文献，搜索用时 31 毫秒
1.
Feng ZY Zheng XJ Tian C Wang Y Xing HY 《Journal of Zhejiang University. Science. B》2011,12(9):704-711
Dysfunction of inhibitory synaptic transmission can destroy the balance between excitatory and inhibitory synaptic inputs
in neurons, thereby inducing epileptic activity. The aim of the paper is to investigate the effects of successive excitatory
inputs on the epileptic activity induced in the absence of inhibitions. Paired-pulse orthodromic and antidromic stimulations
were used to test the changes in the evoked responses in the hippocampus. Picrotoxin (PTX), γ-aminobutyric acid (GABA) type
A (GABAA) receptor antagonist, was added to block the inhibitory synaptic transmission and to establish the epileptic model. Extracellular
evoked population spike (PS) was recorded in the CA1 region of the hippocampus. The results showed that the application of
PTX induced a biphasic change in the paired-pulse ratio of PS amplitude. A short latency increase of the second PS (PS2) was
later followed by a reappearance of PS2 depression. This type of depression was observed in both orthodromic and antidromic
paired-pulse responses, whereas the GABAergic PS2 depression [called paired-pulse depression (PPD)] during baseline recordings
only appeared in orthodromic-evoked responses. In addition, the depression duration at approximately 100 ms was consistent
with a relative silent period observed within spontaneous burst discharges induced by prolonged application of PTX. In conclusion,
the neurons may ignore the excitatory inputs and intrinsically generate bursts during epileptic activity. The depolarization
block could be the mechanisms underlying the PPD in the absence of GABAA inhibitions. The distinct neuronal responses to stimulations during different epileptic stages may implicate the different
antiepileptic effects of electrical stimulation. 相似文献
2.
Inhibitory effects of jujuboside A on EEG and hippocampal glutamate in hyperactive rat 总被引：3，自引：0，他引：3
Lu YJ Zhou J Zhang SM Zhang HY Zheng XX 《Journal of Zhejiang University. Science. B》2005,6(4):265-271
In this study, the inhibitory effect ofjujuboside A (JuA) on a penicillin sodium (Na-PCN) induced hyperactivity model was investigated. Cortical EEG (electroencephalogram) and the concentration of hippocampal Glutamate (Glu) were monitored simultaneously in vivo as indicators of rat's excitatory state. Power spectral density (PSD) and gravity frequency of PSD were calculated. JuA (0.05 g/L and 0.1 g/L) inhibited the EEG excitation effect caused by Na-PCN by increasing the power of δ1 and δ2bands (P＜0.01 vs model) and lowering the gravity frequency of PSD (P＜0.01 vs model). JuA also remarkably reduced the Glu elevation induced by Na-PCN (P＜0.05 vs model). Diazepam also depressed Glu concentration and lowered the gravity frequency,but it showed a different EEG pattern in increased β2-activity (P＜0.01 vs model). EEG excitation caused by Na-PCN correlated with Glu elevation during the first hour. Neurophysiological inhibitory effects of JuA and diazepam were more persistent than their Glu inhibitoty effects. 相似文献
3.
4.
杨杰 《安徽教育学院学报》2003,21(6):70-71
酒精对发育中的脑有严重的损伤作用，如通过阻断NMDA受体和过度激活GABA受体的双重机制，广泛地引起脑部神经元凋亡，消弱胰岛素刺激的小脑神经元存活，抑制齿状回中新细胞的形成并加速细胞凋亡，导致大脑海马区退化性的改变等。 相似文献
5.
Jin Jin-sheng 《浙江大学学报(A卷英文版)》2001,2(4):384-387
The surface morphology and growth mechanism of an aluminum film system deposited on silicone oil surfaces by a vapor depositing
method was investigated by scanning electron microscopy. It was found that the perpendicular fluctuation of the film's bottom
surface was more remarkable than that of the film's top surface. Near the joint between the film on the silicone oil substrate
and the film on the silicon wafer surface on which the silicone oil substrate rested, was a naturally formed anomalous wedge-shaped
wrinkly structure with slopes of 10−4–10−5 rad, whose growth mechanism could be interpreted under the assumption of the thermal expansion behavior of the liquid substrates.
Project supported by NSFC (No. 19874016) and the Special Fund of Zhejiang Provincial Natural Science Foundation for Young
Scientists (Grant No. 1997RC9603). 相似文献
6.
HUANG Da-zhi CHEN Long-zhu 《浙江大学学报(A卷英文版)》2007,8(11):1746-1753
The principle and process of parallel seismic (PS) testing for the integrity testing of cemented soil columns are in- troduced in this paper. A three-dimensional (3D) finite element model (FEM) for the pile-soil system is established for impulse responses. Under saturated soil or unsaturated soil condition, several vibrating velocity-time histories at different depths in parallel hole are obtained based on the numerical simulation. It shows that the length of the pile and the one-dimensional (1D) P-wave velocity in the pile can be determined easily from the features of the mentioned velocity-time histories. By examining the slopes of the first arrival time plotted versus depth or the depth where the amplitude of the first arrival significantly decreases, the length of the pile can be determined. The effects of the 3D P-wave propagation through the saturated soil and the defect of the cemented soil column on the velocity-time histories are also investigated. 相似文献
7.
The effects of Key2Teach on teachers' sense of self-efficacy and emotional exhaustion related to students with externalizing problem behaviour were investigated using an RCT-design. 103 teachers were randomly assigned to an intervention or control condition and followed during a school-year. Data were collected at three time-points. Self-efficacy for instructional strategies improved at post-test and emotional exhaustion decreased at follow-up as a result of Key2Teach. Self-efficacy did not mediate the effect on emotional exhaustion. The effect of Key2Teach on self-efficacy concerning student engagement and classroom management was mediated by an increase in closeness. Implications for research and practice are discussed. 相似文献
8.
Zhou-yan Feng Xiao-jing Zheng Jing Wang 《Journal of Zhejiang University. Science. B》2009,10(7):505-511
Objective: To directly examine the effects of carnosine on neuronal excitation and inhibition in rat hippocampus in vivo. Methods: Artificial cerebrospinal fluid with carnosine was directly administrated over the exposed rat hippocampus. The changes of neuron activity in the CA1 region of hippocampus were evaluated by orthodromically- and antidromically-evoked potentials, as well as paired-pulse stimulation paradigm. Results: In both orthodromic and antidromic response potentials, carnosine transformed population spikes (PSs) with single spike into epileptiform multiple spikes. In addition, similar to the effect of γ-aminobutyric acidA (GABAA) antagonist picrotoxin, carnosine decreased paired-pulse stimulating depression significantly.However, no significant change was observed in the spontaneous field potentials during the application of carnosine. Conclusion:The results indicate a disinhibition-induced excitation effect of carnosine on the CA1 pyramidal neurons. It provides important information against the application of carnosine as a potential anticonvulsant in clinical treatment. 相似文献
9.
10.
In this work, polypropylene （PP）/polystyrene （PS） blends with different organoclay concentrations were prepared via melt compounding. Differing from the results of previous reports, the organoclay platelets are mostly located in the dispersed PS phase instead of the interface. The dimensions of the dispersed PS droplets are greatly reduced and apparent compatibilization effect still exists, which cannot be explained by the traditional compatibilization mechanism. A novel compatibilization mechanism, ＂cutting＂ to apparently compatibilize the immiscible PP/PS blends was proposed. The organoclay platelets tend to form a special ＂knife-like structure＂ in the PS domain under the shear stress of the continuous PP phase during compounding. The ＂clay knife＂ can split the dispersed PS domain apart and lead to the dramatic reduction of the dispersed domain size. 相似文献
11.
韩康宁 《三门峡职业技术学院学报》2021,(1):24-31
生态兴则文明兴。黄河重点生态区生态保护和修复重大工程作为实施全国重要生态系统保护和修复重大工程(2021—2035年)之一,黄河重点生态区在自然生态恢复功能低下形成的生态脆弱和以往经济发展对流域治理的非理性忽视所遗留的生态问题的双重作用下,其所显现的复合性生态环境问题亟待解决,生态保护和修复压力较大。但区域生态修复的责任主体界定模糊;评估、监测、管理程序缺乏系统性明确安排;生态修复资金管理与监督机制不完善;生态修复部门间的信息共享机制有待完善。要从实体和程序两个方面夯实黄河重点生态区修复机制,强化黄河重点生态区生态修复政策的导向性,为黄河流域生态安全和高质量发展提供生态保障,并为全国重要生态保护和修复重大工程提供具有普遍性的机制完善建议。 相似文献
12.
归纳推理的影响因素不同于归纳推理的心理效应。影响个体归纳推理能力的因素主要包括：知识经验。工作记忆的大小，个性特征。对归纳推理的脑机制研究主要从两方面来进行，即对脑损伤病人的研究和神经影像学研究。通过对当前归纳推理中的神经影像学研究的综述发现与归纳推理有关的大脑部位主要是左侧前额叶背外侧部（BA8／9），但是已有的归纳推理的脑机制研究还很贫乏，而且存在很多的不足，加强这一领域的研究有着十分深远的意义。 相似文献
13.
Inhibition of mitochondria responsible for the anti-apoptotic effects of melatonin during ischemia-reperfusion 总被引：7，自引：0，他引：7
Objective： To investigate a possible mechanism responsible for anti-apoptotic effects of melatonin and provide theoretical evidences for clinical therapy. Methods： lschemia-reperfusion mediated neuronal cell injury model was constructed in cerebellar granule neurons （CGNs） by deprivation of glucose, serum and oxygen in media. After ischemia, melatonin was added to the test groups to reach differential concentration during reperfusion. DNA fragmentation, mitochondrial transmembrane potential, mitochondrial cytochrome c release and caspase-3 activity were observed after subjecting cerebellar granule neurons to oxygen-glucose deprivation （OGD）. Results： The results showed that OGD induced typical cell apoptosis change, DNA ladder and apoptosis-related alterations in mitochondrial functions including depression of mitochondrial transmembrane potential （its maximal protection ratio was 73.26%） and release of cytochrome c （its maximal inhibition ratio was 42.52%） and the subsequent activation of caspase-3 （its maximal protection ratio was 59.32%） in cytoplasm. Melatonin reduced DNA damage and inhibited release of mitochondrial cytochrome c and activation of caspase-3. Melatonin can strongly prevent the OGD-induced loss of the mitochondria membrane potential. Conclusion： Our findings suggested that the direct inhibition of mitochondrial pathway might essentially contribute to its anti-apoptotic effects in neuronal ischemia-reperfiusion. 相似文献
14.
完善我国社保基金投资营运策略选择 总被引：3，自引：0，他引：3
随着全球金融市场动荡更加频繁,我国社保基金的投资管理面临严峻形势。因此可以选择一些完善我国社保基金投资营运的策略：通过优化投资管理模式,优选投资工具,建立一个效率优先的社保基金投资营运体制。首先,做到现阶段我国社保基金投资方式多样化、投资组合效益化和风险的有效控制。其次,在个人账户做实后可以适时采用委托投资模式。在优选投资工具方面,可以考虑增加如股指期货和住房抵押贷款证券等创新性金融工具。 相似文献
15.
A relationship between brain responses at birth and later emerging language and reading skills have been shown, but questions
remain whether changes in brain responses after birth continue to predict the mastery of language-related skills such as reading
development. To determine whether developmental changes in the brain-based perceptual skills are systematically related to
differences in word-level reading proficiency at age 8 years, brain event-related potentials (ERPs) to speech and nonspeech
stimuli were recorded annually at the ages of 1 through 8 years in a sample of 109 typically developing children. Two measures
of word-level reading (one that requires decoding of real words and one of pseudowords) were administered at age 8 years.
Growth curve analysis, using the hierarchical linear models, related reading performance (average versus low) to the longitudinal
maturation in the ERP waveform peak and latencies. Maturational changes (e.g., slope, acceleration, and cubic growth) in N1
amplitude from ages 1 to 4 were related to proficiency in decoding pseudoword stimuli only, with children who were less proficient
in decoding pseudowords evidencing more steeply negative declines in amplitude with age, particularly at the frontal and parietal
recording sites in response to both speech and nonspeech stimuli. In contrast, proficiency in decoding real words was related
to developmental changes in N2 amplitudes from ages 4 to 8 only at the parietal recording site, and only in response to nonspeech
stimuli. The early development of biologically based differences in the perception and processing of auditory information
contributes to later group differences in reading proficiencies at school age. 相似文献
16.
Kazimierz ZieliŃski Tomasz Werka W. Jeffrey Wilson Eugeniusz Nikolaev 《Learning & behavior》1995,23(4):438-446
Effects of extended training (nine sessions, 50 trials each) on two-way avoidance response latencies were studied. For each rat, auditory and visual warning signals (CS) were presented on separate trials, either according to a Gellermann series or in 25-trial blocks. Intermittent presentation of the two kinds of trials yielded shorter latencies and higher levels of avoidance performance in response to the noise CS than in response to the darkness CS. Presentation of trials in blocks revealed stronger response-eliciting properties of stimuli presented during the second half of the session than of those presented during the first half. A significant decrease of avoidance performance in the early portions of the delay period, an index of inhibition of delay, was obtained on auditory trials presented in the second half of the sessions. Results indicate that strong fear of the warning signal is required for inhibition of delay of avoidance responses. 相似文献
17.
Complicated geological structures make it difficult to analyze the stability of rock slopes, such as faults, weak intercalated layers or joint fissures. Based on 3D geological modeling and surface block identifying methods, an integrated methodology framework was proposed and realized to analyze the stability of surface blocks in rock slopes. The surface blocks cut by geological structures, fissures or free faces could be identified subjected to the four principles of closure, completeness, uniqueness and validity. The factor of safety(FOS)of single key block was calculated by the limit equilibrium method. If there were two or more connected blocks, they were defined as a block-group. The FOS of a block-group was computed by the Sarma method. The proposed approach was applied to an actual rock slope of a hydropower project, and some possible instable blocks were demonstrated and analyzed visually. The obtained results on the key blocks or block-groups provide essential information for determining potential instable region of rock slopes and designing effective support scheme in advance. 相似文献
18.
The current study examined the effect of the Integrated Model of Advice-giving (Emotional Support—Problem Inquiry and Analysis—Advice) on recipients’ responses to advice, exploring the mediating roles of perceived regard for face and normativeness. Participants read and responded to a conversation in which they received advice from a friend regarding a problematic situation. Results indicated that perceived regard for positive face mediated the relationship between the sequential placement of emotional support and recipients’ responses to advice. Neither perceived regard for face nor normativeness mediated the relationship between the sequential placement of problem inquiry and analysis and recipients’ responses to advice. Findings of this study suggest that the provision of emotional support has a primary role in IMA and is effective in addressing the positive face needs of advice recipient. 相似文献
19.
Database Security and Protection System (DSPS) is a security platform for fighting malicious DBMS. The security and performance
are critical to DSPS. The authors suggested a key management scheme by combining the server group structure to improve availability
and the key distribution structure needed by proactive security. This paper detailed the implementation of proactive security
in DSPS. After thorough performance analysis, the authors concluded that the performance difference between the replicated
mechanism and proactive mechanism becomes smaller and smaller with increasing number of concurrent connections; and that proactive
security is very useful and practical for large, critical applications.
Project (No. 45.6.1-017) supported by the National Defense Pre-Research Fund of China 相似文献
20.
目的：探讨复方丹参片早期干预对APP/PS1转基因小鼠学习记忆的影响及作用机制。方法：4月龄野生型小鼠和APP/PS1转基因小鼠分别灌胃给予溶剂或药物8周后,采用新物体识别实验和跳台实验评价复方丹参片对小鼠行为学表现的影响;应用ELISA检测小鼠海马β淀粉样蛋白（β-amyloid protein,Aβ）Aβ40、Aβ42的含量;采用Real time PCR和Western blot分别检测胰岛素分解酶（insulin degrading enzyme,IDE）/脑啡肽酶（neprilysin,NEP）m RNA和蛋白水平的变化。结果：新物体识别实验结果显示,复方丹参片720 mg·kg-1显著性增加APP/PS1转基因小鼠对新物体的识别指数。跳台实验结果显示,复方丹参片720、360 mg·kg-1显著性减少APP/PS1转基因小鼠学习次数,此外,复方丹参片720 mg·kg-1明显增加小鼠在平台的停留时间。ELISA结果显示,复方丹参片720、360 mg·kg-1显著性降低APP/PS1转基因小鼠海马Aβ40、Aβ42水平。Real-time PCR结果显示,复方丹参片720 mg·kg-1显著性上调APP/PS1转基因小鼠海马IDE和NEP m RNA的表达。Western blot结果显示,复方丹参片720 mg·kg-1显著性增加小鼠海马IDE蛋白表达。结论：复方丹参片可改善APP/PS1转基因小鼠学习记忆能力,可能与减少海马Aβ水平和增加IDE的表达有关。 相似文献