A presynaptic action of glutamate at the cone output synapse

Neurotransmitter release from many central nervous system synapses is regulated by 'autoreceptors' at the synaptic terminal, which bind the released transmitter and alter release accordingly. The photoreceptors of lower vertebrates are thought to use glutamate as a neurotransmitter. Glutamate conveys the visual signal to postsynaptic bipolar and horizontal cells, but has been reported not to act on the photoreceptors themselves. We show here that glutamate evokes a current, carried largely by chloride ions, in cones isolated from the tiger salamander retina. This response is localized to the synaptic terminal of the cone. Removing external sodium blocks this action of glutamate. These results suggest the existence of a positive feedback loop at the cone output synapse: over most of the light-response range, glutamate released by depolarization of the cone will cause further depolarization, increasing the gain of phototransduction. Glutamate released from rods may also polarize cones, modulating the gain of the cone output synapse. This system is surprisingly different from the autoreceptor systems for most other transmitters, which act in a negative feedback way.     

Complexin蛋白通过C端序列加速突触形成

为探究complexin对小鼠大脑皮层神经元生长的影响,将过表达的complexin及突变体导入小鼠大脑皮层神经元.利用共聚焦显微镜对神经元进行免疫荧光成像并利用Image J对突触的密度及平均大小进行分析.结果表明:过表达complexin后,突触密度上升而平均大小无明显变化;去除complexin的C末端后,能明显...     

智能化激光扫描测径仪的研制

通过建立新的扫描测径原理数学模型和提出设置“标准棒”法测量原理提高了测量的精度和稳定性．研制的智能化激光扫描测径仪以ＭＣＳ－５１单片机为核心组成测量控制系统．该系统的硬件部分由８０３１单片机作为主机，软件编制采用相应的汇编语言，具有实时控制、实时输出功能．该仪器作为一种非接触测量仪器，可对生产线上高速运动，高温状态下的棒、线材直径进行动态在线检测．     

计算机实现随机音频信号识别

分析了利用自相关函数法实现快速识别随机音频信号,介绍一种用计算机实现随机音频信号处理与模式识别的硬件结构和程序设计。     

借助 Matlab 提升信号处理教学质量简

介绍将Matlab应用在信号处理的计算机辅助教学中的三种常用方法.借助Matlab的专业工具箱以及可视化技术,结合信号处理课程内容设计出丰富的演示程序,有助于学生对复杂抽象的信号处理理论的理解,提升信号处理课程的教学质量.     

运用张量积网络的信号传递

研究通过运用张量积网络实现信号传递的技术,给出了过程描述和相应的数学模型,并进一步讨论如何在信号过程中,消除或减少输入信号的内部相互作用。     

Centrosome polarization delivers secretory granules to the immunological synapse

Cytotoxic T lymphocytes (CTLs) destroy virally infected and tumorigenic cells by releasing the contents of specialized secretory lysosomes--termed 'lytic granules'--at the immunological synapse formed between the CTL and the target. On contact with the target cell, the microtubule organizing centre of the CTL polarizes towards the target and granules move along microtubules in a minus-end direction towards the polarized microtubule organizing centre. However, the final steps of secretion have remained unclear. Here we show that CTLs do not require actin or plus-end microtubule motors for secretion, but instead the centrosome moves to and contacts the plasma membrane at the central supramolecular activation cluster of the immunological synapse. Actin and IQGAP1 are cleared away from the synapse, and granules are delivered directly to the plasma membrane. These data show that CTLs use a previously unreported mechanism for delivering secretory granules to the immunological synapse, with granule secretion controlled by centrosome delivery to the plasma membrane.     

线性奇异系统输出反馈极点的配置

通过对奇异系统系数矩阵作正交变换，证明了存在微分和比例输出反馈(G，F)使奇异系统正则、无脉冲模且可对n1个极点配置的充要条件是(i)E33=0，E55=0，A33和A55非奇异；(ii)rankec=n2 rank M；(iii)m p-1≥n1，进一步证明了在条件(i)、(ii)成立时，存在联合输出和状态反馈可对奇异系统n1 n2 n4个极点配置。     

Two modes of fusion pore opening revealed by cell-attached recordings at a synapse

Fusion of a vesicle with the cell membrane opens a pore that releases transmitter to the extracellular space. The pore can either dilate fully so that the vesicle collapses completely, or close rapidly to generate 'kiss-and-run' fusion. The size of the pore determines the release rate. At synapses, the size of the fusion pore is unclear, 'kiss-and-run' remains controversial, and the ability of 'kiss-and-run' fusion to generate rapid synaptic currents is questionable. Here, by recording fusion pore kinetics during single vesicle fusion, we found both full collapse and 'kiss-and-run' fusion at calyx-type synapses. For full collapse, the initial fusion pore conductance (G(p)) was usually >375 pS and increased rapidly at > or =299 pS ms(-1). 'Kiss-and-run' fusion was seen as a brief capacitance flicker (<2 s) with G(p) >288 pS for most flickers, but within 15-288 pS for the remaining flickers. Large G(p) (>288 pS) might discharge transmitter rapidly and thereby cause rapid synaptic currents, whereas small G(p) might generate slow and small synaptic currents. These results show that 'kiss-and-run' fusion occurs at synapses and that it can generate rapid postsynaptic currents, and suggest that various fusion pore sizes help to control the kinetics and amplitude of synaptic currents.     

信号序列经小波变换后的相关性分析

针对被处理的对象常常是相互独立的随机信号序列,而波小变换是相以相邻中权平均的结果,通过对信号序列经小波变换后的相关性作定性与定量的分析,得到小波变换后序列的相邻项之间是互不相关且自相关性减半的结果。     

Oxytocin-immunoreactive terminals synapse on oxytocin neurones in the supraoptic nucleus

The neuropeptide oxytocin, synthesized by magnocellular neurones in the hypothalamus, is well known for its peripheral action during lactation and parturition after its release into the bloodstream from axons in the neurohypophysis. However, it may also be released centrally to control the activity of oxytocinergic neurones themselves. Oxytocin release has been measured from isolated magnocellular nuclei in vitro and in the cerebrospinal fluid. When injected into the third ventricle, the peptide increases the basal firing rate of oxytocinergic neurones as well as the frequency and amplitude of the bursts of action potentials they normally show before each reflex milk ejection. Oxytocin also excites magnocellular neurones when applied microiontophoretically. I now report that immunocytochemical staining reveals synapses in the supraoptic nucleus of the hypothalamus where both the pre- and postsynaptic elements contain oxytocin. These oxytocinergic synapses, impinging on their own neurones, may represent the anatomical basis for the hypothalamic release of this peptide and for the facilitatory action on its own secretion.     

控制棒位置测量组合编码电感传感器

控制棒位置是核反应堆最重要的运行参数之一。对于一体化的低温供热堆，棒位测量传感器必须安装在压力容器内，其运行环境及结构空间比压水堆更为苛刻。传统的线圈编码电感传感器线圈数量多、结构复杂。基于理论分析，提出了组合编码方案，所用线圈大大减少。进而进行了编码原理、环境温度影响等试验研究。结果表明：组合编码电感位置传感器原理正确、结构简单、运行可靠，可望发展成２００ＭＷ核供热堆控制棒位置测量的适用传感器     

基于混杂系统设计的视觉输出轨迹跟踪控制

针对视觉控制系统中的输出采样和时延问题,基于间断连续运行混杂系统(PCFHS)方法,设计了具有离散与连续双反馈控制回路的庞特里亚金的优化轨迹跟踪控制器(OPCC),以及基于采样、时延输出能重构系统连续无时延状态的间断连续运行状态观测器(PCFO).与其他输出控制方法相比,基于PCFO的OPCC轨迹跟踪控制设计结构简单,计算量较小,仿真算例验证了所提方法的有效性.