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关键词： 空间方位认知   海马   位置细胞   内嗅皮层   网格细胞  

摘要： 在过去的几十年间,与大脑空间方位认知功能相关的位置细胞、网格细胞、头朝向细胞和边界细胞陆续被发现,它们共同构成了大脑内部的导航定位系统。O'Keefe教授和Moser夫妇这三位科学家也正是由于发现了位置细胞和网格细胞,而共同获得了2014年的诺贝尔生理学或医学奖。

关键词： Brain computer interface  

摘要： In this paper, a novel batch-mode active learning method based on the nearest average-class distance (ALNACD) is proposed to solve multi-class problems with Linear Discriminate Analysis (LDA) classifiers. Using the Nearest Average-class Distance (NACD) query function, the ALNACD algorithm selects a batch of most uncertain samples from unlabeled data to improve gradually pre-trained classifiers' performance. As our method only needs a small set of labeled samples to train initial classifiers, it is very useful in applications like Brain-computer Interface (BCI) design. To verify the e®ectiveness of the proposed ALNACD method, we test the ALNACD algorithm on the Dataset 2a of BCI Competition IV. The test results show that the ALNACD algorithm o®ers similar classification results using less sample labeling e®ort than Random Sampling (RS) method. It also provides competitive results compared with active Support Vector Machine (active SVM), but uses less time than the active SVM in terms of the training.

关键词： 微处理器   人脑   信息处理方式   计算系统   应变能力   能量效率   大脑功能   研制项目  

摘要： 人脑信息处理的应变能力远远超过传统计算系统，能量效率更是后者的100万倍～10亿倍。为了借鉴人脑信息处理方式，在模仿大脑功能的关键器件忆阻器于2008年发明之后，美国和欧洲相继启动多个类脑微处理器研制项目。

摘要： The study of clathrin-coated vesicles (CCVs) isolated from various organs has revealed the identities and important features of many of the factors involved in membrane trafficking. The development of isolation methods using cultured cell lines has made it possible to manipulate the source material before isolation to ask important questions about the roles of these factors and the pathways in which they are involved. We discuss here the advantages and limitations of the use of cultured cell lines for the isolation of CCVs. © 2014 Cold Spring Harbor Laboratory Press.

关键词： 全局渐近稳定性   周期解   反应扩散  

摘要： 文章主要讨论了一类具有反应扩散项的广义高阶脉冲神经网络的稳定性和周期性,通过利用具有脉冲初始条件的时滞微分不等式以及M-锥性质和巴拿赫不动点定理,得到了其周期解的存在唯一性和全局渐近稳定性的充分条件。最后,给出了一个例子来说明研究结果的有效性。

关键词： 定位系统   位置细胞   网格细胞   诺贝尔生理学或医学奖  

摘要： 2014年诺贝尔生理学或医学奖颁发给美国和英国国籍科学家约翰·奥基夫(John O'Keefe)及两位挪威籍科学家梅-布里特·莫泽(May-Britt Moser)和爱德华·莫泽(Edvard ***),表彰他们发现了大脑中的"内置GPS(global positioning system)"——定位系统的细胞学机制。

关键词： Computational neuroscience   Network simulator   Parallel computing   Spiking neural networks   STDP   Synaptic plasticity  

摘要： To understand how the central nervous system performs computations using recurrent neuronal circuitry, simulations have become an indispensable tool for theoretical neuroscience. To study neuronal circuits and their ability to self-organize, increasing attention has been directed toward synaptic plasticity. In particular spike-timing-dependent plasticity (STDP) creates specific demands for simulations of spiking neural networks. On the one hand a high temporal resolution is required to capture the millisecond timescale of typical STDP windows. On the other hand network simulations have to evolve over hours up to days, to capture the timescale of long-term plasticity. To do this efficiently, fast simulation speed is the crucial ingredient rather than large neuron numbers. Using different medium-sized network models consisting of several thousands of neurons and off-the-shelf hardware, we compare the simulation speed of the simulators: Brian, NEST and Neuron as well as our own simulator Auryn. Our results show that real-time simulations of different plastic network models are possible in parallel simulations in which numerical precision is not a primary concern. Even so, the speed-up margin of parallelism is limited and boosting simulation speeds beyond one tenth of real-time is difficult. By profiling simulation code we show that the run times of typical plastic network simulations encounter a hard boundary. This limit is partly due to latencies in the inter-process communications and thus cannot be overcome by increased parallelism. Overall, these results show that to study plasticity in medium-sized spiking neural networks, adequate simulation tools are readily available which run efficiently on small clusters. However, to run simulations substantially faster than real-time, special hardware is a prerequisite. © 2014 Frontiers Research Foundation. All rights reserved.

关键词： 迭代分析方法   反周期解   脉冲   时滞  

摘要： 利用迭代分析方法研究了一类具有脉冲和时滞的细胞神经网络反周期解的存在性和唯一性,以及平衡点的一致稳定性,得到了一些新的结论.