Neural interface with a silicon neural probe in the advancement of microtechnology

In this paper we describe the status of a silicon-based microelectrode for neural recording and an advanced neural interface. We have developed a silicon neural probe, using a combination of plasma and wet etching techniques. This process enables the probe thickness to be controlled precisely. To enhance the CMOS compatibility in the fabrication process, we investigated the feasibility of the site material of the doped polycrystalline silicon with small grains of around 50 nm in size. This silicon electrode demonstrated a favorable performance with respect to impedance spectra, surface topography and acute neural recording. These results showed that the silicon neural probe can be used as an advanced microelectrode for neurological applications.     

Some recent advances in basic neuroscience research in China

Neuroscience as a distinct discipline or research programme has been a rather recent event in most Chinese universities and in the Chinese Academy of Sciences. However, the last few years have witnessed increased funding and an improved research environment for neuroscience, both of which facilitated an influx of Chinese neuroscientists trained abroad. In this review, we have highlighted some recent research advances made by neuroscientists in China. Based on our own expertise, this review is focused mainly on findings that have contributed to our understanding of the mechanisms underlying brain development, neural plasticity and cognitive processes, and neural degeneration.     

Model of autism: increased ratio of excitation/inhibition in key neural systems

Autism is a severe neurobehavioral syndrome, arising largely as an inherited disorder, which can arise from several diseases. Despite recent advances in identifying some genes that can cause autism, its underlying neurological mechanisms are uncertain. Autism is best conceptualized by considering the neural systems that may be defective in autistic individuals. Recent advances in understanding neural systems that process sensory information, various types of memories and social and emotional behaviors are reviewed and compared with known abnormalities in autism. Then, specific genetic abnormalities that are linked with autism are examined. Synthesis of this information leads to a model that postulates that some forms of autism are caused by an increased ratio of excitation/inhibition in sensory, mnemonic, social and emotional systems. The model further postulates that the increased ratio of excitation/inhibition can be caused by combinatorial effects of genetic and environmental variables that impinge upon a given neural system. Furthermore, the model suggests potential therapeutic interventions.     

Microfabricated nerve–electrode interfaces in neural prosthetics and neural engineering

Neural interfaces and implants are finding more clinical applications and there are rapid technological advances for more efficient and safe design, fabrication and materials to establish high-fidelity neural interfaces. In this review paper, we highlight new developments of the microfabricated electrodes and substrates with regard to the design, materials, fabrication and their clinical applications. There is a noticeable trend towards integration of microfluidic modules on a single neural platform. In addition to the microelectrodes for neural recording and stimulation, microfluidic channels are integrated into a nerve–electrode interface to explore the rich neurochemistry present at the neural interface and exploit it for enhanced electrochemical stimulation and recording of the central and peripheral nervous system.     

Distinct roles for Distal-less genes Dlx3 and Dlx5 in regulating ectodermal development in Xenopus

In vertebrates, there are six or more copies of genes related to the Drosophila pattern formation homeodomain gene Distal-less. Among this family, Dlx3 and Dlx5 share extensive sequence homology and have similar, but distinctive, expression patterns, suggesting that these two factors may have substantially redundant developmental functions. Here we show that at the earliest phases of embryogenesis in Xenopus, there are significant differences between Dlx3 and Dlx5 expression and that this correlates with different functions in the restriction of neural crest and neural plate boundaries, respectively.     

神经干细胞在治疗脑损伤中的应用

神经干细胞（neural stem cells,NSCs）是中枢神经系统中既具有自我更新能力又能分化为神经系统各类细胞的细胞群。在体外一定条件下,NSCs能保持增殖能力,经定向诱导能分化为具有成熟神经细胞特征的各类细胞。NSCs移植治疗研究显示,植入的NSCs能分化为移植部位的神经细胞,并融入、整合该部位,重建受损神经网络,在一定程度上缓解病症。近年来,激活体内内源NSCs治疗神经损伤也逐渐得到广泛关注。因此,NSCs在治疗神经损伤中的应用研究已成为当前神经生物学基础理论和临床应用研究的热点。本文简要介绍了最近关于NSCs在治疗脑损伤中的应用研究进展。     

Neural inhibition of egg-laying in the locust, Locusta migratoria

The role of the oviducal nerves during egg-laying in Locusta migratoria has been examined. Section of the oviducal nerves did not inhibit egg-laying in any observable way. Electrical stimulation of the oviducal nerves resulted in a contraction of the common and lower lateral oviducts which propelled ovulated eggs up towards the ovaries. Recordings from oviducal nerves using chronically implanted electrodes showed that electrical activity was low during actual egg-laying, but high at times when egg-laying was not occurring (i.e. during digging behaviour, or following interruption of egg-laying). During these periods of high activity recurrent bursts of action potentials occurred. Similar patterns of electrical activity were recorded in semi-intact preparations using suction electrodes applied to exposed oviducal nerves of locusts which had been interrupted during the process of egg-laying. High frequency bursts of activity were recorded simultaneously from both left and right oviducal nerves.It is concluded that one function of the oviducal nerves is to inhibit egg-laying at inappropriate times, by inducing contractions of the oviducts which propel eggs back towards the ovaries. These nerves therefore provide a physiological basis for part of the adaptive ovipositional activities of locusts.     

Prediction of the disulfide-bonding state of cysteines in proteins at 88% accuracy

The task of predicting the cysteine-bonding state in proteins starting from the residue chain is addressed by implementing a new hybrid system that combines a neural network and a hidden Markov model (hidden neural network). Training is performed using 4136 cysteine-containing segments extracted from 969 nonhomologous proteins of well-resolved three-dimensional structure. After a 20-fold cross-validation procedure, the efficiency of the prediction scores as high as 88% and 84%, when measured on cysteine and protein basis, respectively. These results outperform previously described methods for the same task.     

Rapid changes in gustatory function induced by contralateral nerve injury and sodium depletion

The combination of dietary sodium depletion and unilateral chorda tympani (CT) nerve section decreases sodium taste function in the intact CT nerve. However, functional changes have not been examined prior to day 4 postsectioning, even though degenerative and inflammatory responses are robust during that period. Rats received unilateral CT section and/or dietary sodium depletion, accomplished by 2 injections of furosemide and a sodium-restricted diet, on day 0. Surgical controls received sham nerve sectioning. At days 1, 2, 3, or 4, taste responses were recorded from the intact nerve. Functional changes were rapid and unexpected. At day 1 postsectioning, neural responses from the uninjured CT of both control-fed and sodium-depleted animals were reduced. By day 2, however, normal function was restored in control-fed rats, whereas functional deficits persisted in depleted animals. Sodium depletion alone also induced a transient decrease in sodium responses at days 2-3 after furosemide injection. These results demonstrate that distant neural injury can elicit gustatory plasticity regardless of the dietary environment, but normal responses can be restored. We suggest that neutrophils mediate the initial postinjury deficits in taste function, whereas macrophages promote the recovery of normal function.     

Variation in large-bodied fish-community structure and abundance in relation to water-management regime in a large regulated river

Variation in life-history traits (growth, condition, mortality and recruitment) and relative abundance of 11 large-bodied fish species was investigated among three water-management regimes (unimpounded, run-of-the-river and winter reservoirs) in the large regulated Ottawa River, Canada. If waterpower management had an effect on fishes, then (1) would be expected community structuring among water-management regimes and (2) species with similar life-history traits should be affected in a similar manner. Large-bodied fish communities were assessed using two different standard index-netting techniques, one using trap nets and the other gillnets. Community structure could be discriminated based on species caught in nets using holographic neural networks (78·8% correct overall classification rate using trap nets and 76·0% using gillnets); therefore, water-management regimes affected community structure in the Ottawa River. Littoral zone benthivores were significantly lower in abundance ( P < 0·001) or absent in winter reservoirs, whereas the abundance of planktivores or species that were planktivorous at young ages were significantly greater than in unimpounded river reaches. Growth, condition and mortality did not vary among reach types except smallmouth bass Micropterus dolomieu were in better condition in winter reservoirs than unimpounded reaches. Lake sturgeon Acipenser fulvescens recruitment was impaired in run-of-the-river reaches, whereas recruitment for other species that spawn in fast water was not affected.     

Convergence in Continuous Hopfield Neural Network with Delays

IIntroductionWeconsiderthenetworkbasedonHopfleldcircuitequationwiththeadditionofdelayswhereu;（t）IstheInPutvoltageofthel一thneuron,C;IscaPacitance,KIsthetotalresls－tanceattheInputofneuron。,人Isslgmoldaltransferfunction．Inthispaper,weconsiderthenormalizedsystemof（l）。fthetypeThereexistsanextensivekeratureonvariousaspectsofsystemsoftheform（2）withandwithouttimedelays,werefertoEI,2,3jandthereferencescitedtherein．ThepurposeofthispaperIstoderivesufficientconditionsfortheglobal…     

成年哺乳动物皮质区神经发生的研究进展

神经发生是神经干细胞在适当的条件下分化成功能性整合神经元的过程,主要包括细胞的增殖、迁移、分化和存活。成年神经发生区以前脑室管膜下区(Subventricular zones,SVZ)和海马齿状回颗粒层下区(Subgranular zones,SGZ)为主,但皮质作为神经元和神经胶质细胞数量最多、分布最广,同时也是哺乳动物高度发展的脑区,是否有成年神经元新生,已成为近年来神经科学领域的研究热点[1,2]。现本文就未成熟神经元在皮质区的研究方法、分布、来源与转归、病理生理功能影响等方面探讨成年哺乳动物皮质神经发生现象。     

Characterization of a novel transgenic mouse line expressing Cre recombinase under the control of the Cdx2 neural specific enhancer

Several genetically modified mouse models have been generated in order to drive expression of the Cre recombinase in the neuroectoderm. However, none of them specifically targets the posterior neural plate during neurulation. To fill this gap, we have generated a new transgenic mouse line in which Cre expression is controlled by a neural specific enhancer (NSE) from the Caudal‐related homeobox 2 (Cdx2) locus. Analyses of Cre activity via breeding with R26R‐YFP reporter mice have indicated that the Cdx2NSE‐Cre mouse line allows for recombination of LoxP sites in most cells of the posterior neural plate as soon as from the head fold stage. Detailed examination of double‐transgenic embryos has revealed that this novel Cre‐driver line allows targeting the entire posterior neural tube with an anterior limit in the caudal hindbrain. Of note, the Cdx2NSE regulatory sequences direct Cre expression along the whole dorso‐ventral axis (including pre‐migratory neural crest cells) and, accordingly, YFP fluorescence has been also observed in multiple non‐cranial neural crest derivatives of double‐transgenic embryos. Therefore, we believe that the Cdx2NSE‐Cre mouse line represents an important novel genetic tool for the study of early events occurring in the caudal neuroectoderm during the formation of both the central and the peripheral nervous systems. genesis 51:777–784. © 2013 Wiley Periodicals, Inc.     

A Network Model of Motion Processing in Area MT of Primates

A simple and biologically plausible model is proposed to simulatethe visual motion processing taking place in the middle temporal (MT) areaof the visual cortex in the primate brain. The model is ahierarchical neural network composed of multiple competitive learninglayers. The input layer of the network simulates the neurons in the primaryvisual cortex (V1), which are sensitive to the orientation and motionvelocity of the visual stimuli, and the middle and output layers of thenetwork simulate the component MT and pattern MT neurons, which areselectively responsive to local and global motions, respectively. Thenetwork model was tested with various simulated motion patterns (random dotsof different direction correlations, transparent motion, grating and plaidpatterns, and so on). The response properties of the model closely resemblemany of the known features of the MT neurons found neurophysiologically.These results show that the sophisticated response behaviors of the MTneurons can emerge naturally from some very simple models, such as acompetitive learning network.     

多通道神经信号分析方法及其应用

在神经科学研究中,多通道记录方法被普遍应用在对神经元群体活动特性的研究中.通过分析多个神经元的活动,可以了解神经系统协同编码外界信息的规则以及大脑实现各项功能的机制.为了挖掘出多通道神经信号中携带的信息及其潜在的相关性,需要合适的计算方法辅助对神经元放电活动进行解码.本文回顾了多通道神经信号分析中的一些常见方法,以及它...     

小胶质细胞在脑中的生理功能

小胶质细胞是脑中的巨噬细胞,也是脑实质中唯一的一种免疫细胞,因而被看作是中枢神经系统抵御病原入侵的第一道防线。在其他非感染病理状态下,如脑损伤及神经退行性疾病等,小胶质细胞也发挥着保护和毒性损伤的双重作用。相比较其病理功能,人们对小胶质细胞的生理功能长期以来很少关注。然而,近几年关于小胶质细胞生理功能的研究在多个方面都有突破。这些研究结果揭示,小胶质细胞在发育的神经系统中起着调控神经元存活和修饰突触的作用,并且在成熟的健康脑中具有探测和调控神经元活动的功能。将着重对近几年关于小胶质细胞生理功能的相关研究做一综述。     

神经干细胞/前体细胞分化的功能学鉴定研究进展

神经干细胞／前体细胞分化是神经生物学研究的热点．以往对神经干细胞／前体细胞分化水平的鉴定主要依赖于形态学指标,而随着膜片钳技术的应用,神经干细胞／前体细胞分化过程中膜电特性的改变、离子通道活动等功能学指标越来越受到重视．综述了利用膜片钳技术研究神经干细胞／前体细胞功能分化的最新进展,并对存在的问题做出思考和展望．     

Neural Population Structures and Consequences for Neural Coding

Researchers studying neural coding have speculated that populations of neurons would more effectively represent the stimulus if the neurons "cooperated:" by interacting through lateral connections, the neurons would process and represent information better than if they functioned independently. We apply our new theory of information processing to determine the fidelity limits of simple population structures to encode stimulus features. We focus on noncooperative populations, which have no lateral connections. We show that they always exhibit positively correlated responses and that as population size increases, they perfectly represent the information conveyed by their inputs regardless of the individual neuron's coding scheme. Cooperative populations, which do have lateral connections, can, depending on the nature of the connections, perform better or worse than their noncooperative counterparts. We further show that common notions of synergy fail to capture the level of cooperation and to reflect the information processing properties of populations.