参数未知神经元模型的全阶与降阶最优同步

基于Lyapunov稳定性理论、最优控制原理以及分步设计方法, 为神经元系统设计了非线性反馈控制器和最优控制器. 其中非线性反馈控制器能使得两个神经元系统之间的轨道误差趋于零, 最优控制器使得在同步过程中所花费的能量达到最低. 本文以Cable模型为例, 实现了两个神经元模型的全阶最优同步; 以Cable 模型和Hindmarsh-Rose (HR)模型为例, 实现了两个神经元模型的降阶最优同步; 同时, 均能有效地辨识出系统参数. 最后通过数值模拟进一步验证了本方案的有效性.     

Identifying elements of the probabilistic neuronal ensembles from the standpoint of fuzzy sets theory

The paper presents the results of investigation of the neuron of the frog visual analyzer central part and the crayfish 6th abdominal ganglion on the basis of fuzzy sets theory and some set-theoretical operations to establish the neuron membership in a particular ensemble in accordance with their essential characteristics.     

Brain stem neuronal noise and neocortical “resonance”

We present a qualitative model and data in evidence for the selection and stabilization of neocortical brain-wave power spectral modes by slow periodic and fast noise driving by brain stem neurons. Unlike noise effects in a bistable potential, increasing noise amplitude via more brain stem neurons increases the measure on unstable manifolds trapped in the saddle-sinks of the neural membrane attractor andincreases dwell times. We suggest that the effect of noise in expanding dynamical systems such as the generalized neuronal membrane equations studied here may be analogous to that of many-frequency quasiperiodic driving which leads to the stabilization of the EEG as a strange, nonchaotic attractor.     

Influence of membrane surface properties on the growth of neuronal cells isolated from hippocampus

Membranes have become of great interest for tissue engineering application, since they offer the advantage of developing neuronal tissue that may be used in implantable or in vitro hybrid systems for the simulation of brain function. The behaviour of neurons isolated from the hippocampus on membranes with different surface properties was investigated.     

Reciprocity between the cerebellum and the cerebral cortex: Nonlinear dynamics in microscopic modules for generating voluntary motor commands

The cerebellum and basal ganglia are reciprocally connected with the cerebral cortex, forming many loops that function as distributed processing modules. Here we present a detailed model of one microscopic loop between the motor cortex and the cerebellum, and we show how small arrays of these microscopic loops (CB modules) can be used to generate biologically plausible motor commands for controlling movement. A fundamental feature of CB modules is the presence of positive feedback loops between the cerebellar nucleus and the motor cortex. We use nonlinear dynamics to model one microscopic loop and to investigate its bistable properties. Simulations demonstrate an ability to program a motor command well in advance of command generation and an ability to vary command duration. However, control of command intensity is minimal, which could interfere with the control of movement velocity. To assess these hypotheses, we use a minimal nonlinear model of the neuromuscular (NM) system that translates motor commands into actual movements. Simulations of the combined CB‐NM modular model indicate that movement duration is readily controlled, whereas velocity is poorly controlled. We then explore how an array of eight CB‐NM modules can be used to control the direction and endpoint of a planar movement. In actuality, thousands of such microscopic loops function together as an array of adjustable pattern generators for programming and regulating the composite motor commands that control limb movements. We discuss the biological plausibility and limitations of the model. We also discuss ways in which an agent‐based representation can take advantage of the modularity in order to model this complex system. © 2008 Wiley Periodicals, Inc. Complexity, 2008     

Shank 2 expression coincides with neuronal differentiation in the developing retina

The retinal activity for vision requires a precise synaptic connectivity. Shank proteins at postsynaptic sites of excitatory synapses play roles in signal transmission into the postsynaptic neuron. However, the correlation of Shank 2 expression with neuronal differentiation in the developing retina remains to be elucidated regardless of previous evidences of Shank 2 expression in retina. Herein, we demonstrated that with progression of development, Shank 2 is initially detected in the inner plexiform layer at P2, and then intensively detected in inner plexiform layer, outer plexiform layer, and ganglion cell layer at P14, which was closely colocalized to the neurofilament expression. Shank 2 was, however, not colocalized with glial fibrillary acidic protein. Shank 2 expression was increased in the differentiated retinoblastoma cells, which was mediated by ERK 1/2 activation. Moreover, Shank 2 expression was colocalized with neurofilament at the dendritic region of cells. In conclusion, our data suggests that Shank 2 is expressed in the neurons of the developing retina and could play a critical role in the neuronal differentiation of the developing retina.     

带时滞的二元神经元网络的OPNCL控制和复杂网络的时间延迟反馈控制

针对一种带时滞的二元神经元网络和一种复杂网络的混沌控制问题,利用开环加非线性闭环(Open Plus Nonlinear Closed Loop,OPNCL)方法和时间延迟反馈控制(Time Delay FeedbackControl,TDFC)方法,分别设计了该混沌网络和混沌系统的控制器。从理论上证明了第一种控制器可使该网络系统的解稳定地传递到选定的目标,并通过数值模拟实验进一步验证了两种方法的有效性。结果表明:该方法避免了开环加非线性闭环控制的一些限制因素;对于任何目标,所控制混沌系统的传递域(Basins of Entrainment)是全局的,避免了有关确定传递域范围的繁琐计算。     

Spiral Wave in Small-World Networks of Hodgkin--Huxley Neurons

The effect of small-world connection and noise on the formation and transitionof spiral wave in the networks of Hodgkin-Huxley neurons are investigated in detail. Some interesting results are found in our numerical studies. i) The quiescent neurons are activated to propagate electric signal to others by generating and developing spiral wave from spiral seed in small area. ii) A statistical factor is defined to describe the collective properties and phase transition induced by the topology of networks and noise. iii) Stable rotating spiral wave can be generated and keeps robust when the rewiring probability is below certain threshold, otherwise, spiral wave can not be developed from the spiral seed and spiral wave breakup occurs for a stable rotating spiral wave. iv) Gaussian white noise is introduced on the membrane of neuronsto study the noise-induced phase transition on spiral wave in small-world networks of neurons. It is confirmed that Gaussian white noise plays active role in supporting and developing spiral wave in the networks of neurons, and appearance of smaller factor of synchronization indicates high possibility to induce spiral wave.     

镧对大鼠海马神经元瞬时外向钾电流和延迟整流钾电流动力学的影响

利用全细胞膜片钳技术, 在急性分离的大鼠海马锥形细胞上研究了La³⁺对快速激活与失活的瞬时外向钾电流IA和平台电流IK的影响. 结果发现, 随着细胞外液中La ³⁺浓度的增加, La ³⁺对IA的抑制率逐渐增大, 而且具有电压依赖性; 10^-5 mol/L La ³⁺可改变IA激活曲线和失活曲线的半数激活电压Vh值, 使激活曲线和失活曲线左移, 但不改变其斜率因子k值. 细胞外液中 La ³⁺对IK及其激活曲线都没有明显作用. 这可能是镧导致海马神经元异常的作用机制之一.     

Orbitrap mass spectrometry for monitoring the ganglioside pattern in human cerebellum development and aging

We have developed here a superior approach based on high‐resolution (HR) mass spectrometry (MS) for monitoring the changes occurring with development and aging in the composition and structure of cerebellar gangliosidome. The experiments were focused on the comparative screening and structural analysis of gangliosides expressed in fetal and aged cerebellum by Orbitrap MS with nanoelectrospray ionization (nanoESI) in the negative ion mode. The employed ultrahigh‐resolution MS platform allowed the discrimination, without the need of previous separation, of 159 ions corresponding to 120 distinct species in the native ganglioside mixtures from fetal and aged cerebellar biopsies, many more than detected before, when MS platforms of lower resolution were employed. A number of gangliosides, in particular polysialylated belonging to GT, GQ, GP, and GS classes, modified by O‐fucosylation, O‐acetylation, or CH₃COO^? were discovered here, for the first time in human cerebellum. These components, found differently expressed in fetal and aged tissues, indicated that the ganglioside profile in cerebellum is development stage‐ and age‐specific. Following the fragmentation analysis by high‐energy collision‐induced dissociation (HCD) tandem MS (MS/MS), we have also observed that the intimate structure of certain compounds has not changed during the development and aging of the brain, an aspect which could open new directions in the investigation of ganglioside biomarkers in cerebellar tissue.