一种用于单位放电的晶体管鉴频器

一种用于细胞外单位放电的鉴频器,放电信号经放大、鉴别、整形而后按放电频率转变为模拟电压,可由描笔记录器或示波器显示电压曲线。并有阻断刺激伪迹电路,以免伪迹误入鉴频器。本仪器可在电生理实验中立即观察单位放电的频率变化。     

离体神经动作电位不同记录方法对刺激伪迹的影响

在蟾蜍离体神经动作电位记录中,系统地观察了不同引导方法与不同刺激方法对刺激伪迹的影响,并且分析了伪迹产生的原因。用隔离变压器刺激神经,刺激电流通过刺激电极与引导电极间的神经、栅漏电阻以及隔离变压器与地之间的电容所组成的阻容串联电路时在栅漏电阻上的分压输入到放大器即表现为伪迹。采用适当的引导方法或减小刺激装置与地间的电容,都可以减小刺激伪迹。当以隔离变压器刺激神经时采用单边输入引导方法将近刺激侧的引导电极接地,伪迹不会很大。不论单边或双边输入引导,在刺激与引导电极之间离引导电极3—5毫米处加一接地电极能使伪迹更进一步减小,甚至完全消失。     

CP-1型多用生物电脉冲处理仪

在神经电生理的实验中,实验者经常需要从记录到的脉冲信号或含有刺激伪迹的信号中选出自己所需要的信号。实验者也常需要在实验过程中及时了解电活动的种种变化。这种“实时”的信息对于实验者合理安排实验是十分重要的。目前常采用幅值窗电路和积分电路来完成信号的选取和记录。但因幅值窗电路是根据放电幅度大小而不根据波宽的不同选取     

介绍一种记录不同神经元单位放电的积分器

应用微电极记录单个神经元放电时,需及时处理放电的频率和振幅。目前国内有的单位采用计算机处理;有的单位采用示波器连续照相后再做统计;还有一些单位采用晶体管泵鉴频器电路将放电的数字量转变为电压模拟量来记录。我们实验室根据处理神经元单位放电的需要,最近设计了一种能统计不同神经元连续单位放电的积分仪。该仪器能将不同幅度的脉冲分别加以记录;也能有效地去除刺激伪迹;根据需要还可分别选择以1、2、3、4、5秒的时间间隔统计放电频率,用长图记录仪自动描绘出放电脉冲的频率—时间图。这样,在实验过程中,就可以立即了解神经元放电频率的变化。该电路结构简单、性能稳定、价格便宜,     

基于独立元分析和非线性指数分析的脑电信号中伪迹分量的自动去除

脑电(electroencephalography,EEG)信号中不可避免地存在着眼动、心跳、肌电信号以及线性噪声等伪迹干扰,这些伪迹的存在极大地影响了脑电信号分析的准确性,因此在进行脑电信号分析前需要去除伪迹干扰。为了有效地去除伪迹,结合独立元分析和非线性指数分析,提出一种自动识别并去除脑电信号中伪迹分量的方法。该方法还可同时用于提取脑电信号中的基本节律如!波等。相应的模拟与实际脑电数据的实验结果表明所提议的方法具有很好的识别和去除脑电信号伪迹分量的性能。     

深部脑刺激对大鼠丘脑底核神经活动的影响

为了探求高频电刺激对受刺激核团的影响,在高频刺激丘脑底核的同时,同步记录了大鼠丘脑底核神经元活动．针对同步记录中刺激伪迹的难题,研究并应用了高效的刺激伪迹滤出算法,恢复了被掩盖的神经响应,且失真小．研究了刺激幅度、频率与神经元神经响应类型的关系,以及在临床治疗有效刺激参数下,高频刺激对神经元平均放电率的影响．研究结果显示,放电率的变化可能与帕金森症病理状态无直接关系,爆发式放电增多更可能是帕金森发病潜在的电生理基础,而受刺激核团的自发放电的抑制、放电率的降低及爆发式放电的减少则有可能是深部脑刺激作用机制的一部分．     

一种用于自由活动动物的微型多模式遥控刺激器

本文采用集成有射频功能的片上系统(nRF24E1),研制了一种用于自由活动小动物的微型多模式遥控刺激器。刺激参数的设置及结果分析均由10 m外的个人计算机进行。通过离体实验,即刺激蛙坐骨神经干时产生动作电位并可观察到伪迹;及在体大鼠的训练操作性条件反射的行为学实验,即在Y臂迷宫中训练大鼠听到不同声音完成左右运动,如果完成正确给予前脑内侧束以电刺激,我们观察到5 d内大鼠的正确率增加3倍,达到93．5％。上述实验都验证了该刺激器的有效性与稳定性。本系统具有体积小(18 mm×28 mm双层线路板)、重量轻(不含电池5 g)、简单、实用、可靠等特点,能有效地用于自由活动小动物的实验研究。为基于电刺激的小动物行为训练(动物机器人)及相关神经生理学实验研究,提供了新的实验条件和实验手段。     

神经冲动积分仪

本文主要介绍一种新的神经冲动积分仪结构原理。由于在仪器设计中,采用了线性的模数转换和十二位(BIN)的数模转换电路,配合其它数字逻辑之后,使仪器除了具有置零积分,平均值电路功能外,还具有频率直方图和幅度直方图处理功能,并同时有六位数字显示和声音监听,尤其更适合于用来描绘变化较慢而又需长时间观察的各种生物电的实验信息。线路中由于设置了去除电刺激伪迹装置和阈值电平调节,使仪器能有效地抑制各种干扰信号。     

刺激鲫鱼小脑腹外侧区诱发的Mauthner细胞兴奋性突触后电位

实验采用微电极胞内记录技术探查鲫鱼Mauthner细胞(M-细胞)对小脑刺激的电反应特征。电刺激鲫鱼小脑腹外侧部,可在双侧M-细胞胞体、腹侧树突和外侧树突近端记录到一种复合性兴奋性突触后电位(小脑诱发性EPSP)。小脑诱发性EPSP潜伏期较短(0.63±0.09 ms),持续时间较长(5.49±1.13 ms),幅度分级和刺激频率依从等特征。以较高强度刺激小脑常引起M-细胞顺向激活。多点胞内连续穿刺实验显示小脑诱发性EPSP起源于腹侧树突远端。实验结果提示,小脑-M-细胞通路可能包含一组长短不等的神经元链,它们根据链的短或长,由近及远依次投射在腹侧树突远端。     

微碳纤电极与细胞量子化分泌的记录方法

电生理研究细胞分泌有两种实时记录技术。膜电容法通过记录细胞表面积来估算刺激诱导的细胞分泌和胞吞导致的膜表面积总和变化。微碳纤电极（carbon fiber electrode,CFE )法则可单纯记录细胞分泌。CFE记录灵敏度是当前最高水平,可记录单个50nm突触小泡的量子递质释放。介绍CFE基本记录方法、原理和一些实验应用。     

一种动物实验监控系统的设计

本文主要设计动物生命体征参数（体温、呼吸率和脉搏率）的监控系统。硬件电路采用MSP430F5438芯片作为微控制器,体温、呼吸和脉搏生理参数的信号采集使用了相应的信号调理电路和处理电路,主要由电信号转换电路、放大滤波电路、AD转换电路、脉冲转换电路、LCD显示电路、加热垫和蜂鸣器驱动电路等组成。     

除颤器中充电电路设计与研究

介绍了利用UC3845的PWM去控制反激式充电电路,将该电路运用于体外除颤器中,改变传统电路的正激式充电方式,大大提高了充电效率,缩短了充电时间。此外,还对电路中变压器设计作了详细的计算和对电路的工作原理进行了分析。     

Current-to-voltage convertor for measurement of oxygen

A highly sensitive, miniature, inexpensive circuit for the measurement of PO2 in vivo has been described. The circuit is constructed from a current-to-voltage convertor, clamping circuit, differential amplifier, and reverse voltage and overvoltage protector. The design of the circuit allows us to apply voltage bias to the measuring electrode while grounding the preparation. The clamping circuit holds the selected bias voltage constant while the differential amplifier subtracts this bias potential from the PO2 signal yielding an output voltage that is proportional to the current sensed by the oxygen electrode. The circuit is protected from reverse voltage and overvoltage.     

Monolithically integrated bacteriorhodopsin/semiconductor opto-electronic integrated circuit for a bio-photoreceiver

The light-sensitive protein, bacteriorhodopsin (BR), is monolithically integrated with an InP-based amplifier circuit to realize a novel opto-electronic integrated circuit (OEIC) which performs as a high-speed photoreceiver. The circuit is realized by epitaxial growth of the field-effect transistors, currently used semiconductor device and circuit fabrication techniques, and selective area BR electro-deposition. The integrated photoreceiver has a responsivity of 175 V/W and linear photoresponse, with a dynamic range of 16 dB, with 594 nm photoexcitation. The dynamics of the photochemical cycle of BR has also been modeled and a proposed equivalent circuit simulates the measured BR photoresponse with good agreement.     

Analog VLSI implementation of resonate-and-fire neuron

We propose an analog integrated circuit that implements a resonate-and-fire neuron (RFN) model based on the Lotka-Volterra (LV) system. The RFN model is a spiking neuron model that has second-order membrane dynamics, and thus exhibits fast damped subthreshold oscillation, resulting in the coincidence detection, frequency preference, and post-inhibitory rebound. The RFN circuit has been derived from the LV system to mimic such dynamical behavior of the RFN model. Through circuit simulations, we demonstrate that the RFN circuit can act as a coincidence detector and a band-pass filter at circuit level even in the presence of additive white noise and background random activity. These results show that our circuit is expected to be useful for very large-scale integration (VLSI) implementation of functional spiking neural networks.     

Wet processed and dry phototools in the manufacturing of printed circuit boards

In the manufacturing of printed circuit boards, the pattern of the copper circuits is first generated on a photographic film (the ‘phototool’). These phototools are then used to copy the circuit patterns to the printed circuit boards. In order to generate the circuit pattern on a conventional silver film, the film is exposed to light in a photoplotter and then chemically processed. Mastertool® is a new dry phototool for the production of printed circuit boards. It is based on bismuth instead of silver and does not require chemical processing after exposure. A comparative LCA of Mastertool® and silver film shows that Mastertool® causes significantly less environmental impacts over its entire lifecycle. The underlying reasons are threefold. First, thanks to its improved technical characteristics, Mastertool® has a longer lifetime. Second, its use requires less energy because no chemical processing is needed. Finally, no photographic chemicals are needed and no silver containing chemical waste is produced in the printed circuit board production.     

Circuit for the electromanipulation of plant protoplasts

An electric circuit for plant protoplast manipulation is described. The circuit used readily available materials and was designed for use in teaching. This integrated circuit can be placed in a single small box with controls for the aligning voltage, the aligning frequency, the pulse voltage, and the pulse timing. The circuit can be supplied by any suitable source of dc power and can be easily altered for individual requirements. The circuit, as presented here, can be assembled for less than $250.     

A theory of steady-state activity in nerve-fiber networks: IV.N circuits with a common synapse

Conditions under which either of two distinct activity patterns may arise from the same stimulus pattern are deduced for the case of a net-work which consists ofN simple circuits all jointed at a common synapse. If the product of the activity parameters of all the fibers in any circuit is called the activity parameter of the circuit, or, more briefly, the circuit parameter, then the condition for the existence of such mutually consistent activity patterns is that there be a sum of circuit paramaters which is not less than unity.     

A theory of steady-state activity in nerve-fiber networks III: The simple circuit in complete activity

Continuing the investigation previously introduced, it is shown here that when the product of the activity parameters of the circuit is not exceeded by unity (algebraically) a steady state is not possible in which all fibers of the circuit are active, whereas when this product is exceeded by unity, any stimulus pattern which is consistent with such a state of complete activity is inconsistent with any state of partial activity of the circuit.     

An electronic analog of synthetic genetic networks

An electronic analog of a synthetic genetic network known as the repressilator is proposed. The repressilator is a synthetic biological clock consisting of a cyclic inhibitory network of three negative regulatory genes which produces oscillations in the expressed protein concentrations. Compared to previous circuit analogs of the repressilator, the circuit here takes into account more accurately the kinetics of gene expression, inhibition, and protein degradation. A good agreement between circuit measurements and numerical prediction is observed. The circuit allows for easy control of the kinetic parameters thereby aiding investigations of large varieties of potential dynamics.