中枢神经元放电的在体多通道同步记录技术

中枢神经元放电的在体多通道同步记录技术是采用细胞外记录的方法来监测神经元群的同步电活动。该系统包括微电极阵列(microarray)、数据采集和分析系统。应用这一技术可以同步记录多个脑区的大量神经元的电活动,研究不同脑区的神经元放电在时间和空间上的联系,进而通过分析神经元的放电模式来研究大脑对外部事件的编码机制。     

Chicken retinal ganglion cells response characteristics: multi-channel electrode recording study

A fundamental question in neuroscience is how the information relevant to behavior is presented in the activity of neurons[1]. The visual system, especially the retina, offers some advantage to explore the neural code owing to its explicitly layered structure and relatively simple neuron types[2]. However, most of what we know about retinal signaling is derived from single neuron recordings[2,3]. The assumptions underlying this approach are that individual neuron acts as a unique element dedi…     

Chicken retinal ganglion cells response characteristics: multi-channel electrode recording study

The first stage of visual processing occurs in the retina, the function of which is to process the raw information obtained from the outside world. In the present study, the electrical activities of a group of retinal ganglion cells were recorded from a small functioning piece of retina, using multi-electrode array (MEA), and the action potentials were detected by applying nonlinear algorithm. By analyzing the ensemble retinal ganglion output characteristics, it is revealed that both firing rates and correlated activity between adjacent neurons in the retina contribute to visual information encoding.     

Feedback in physiological systems: An application of feedback analysis and stochastic models to neurophysiology

In the human, the antagonistic, extensor-flexor system of the leg is an example of a common type of neurophysiological feedback system. After a brief introduction to the neuroanatomy and physiology of this feedback system, the paper formulates transfer functions from temporal response data available in the literature. A feedback stability analysis, based on the extension of Nyquist's stability criteria to multiple-loop systems and utilizing flow-graph techniques, demonstrates the stable behavior of the system. Expressions are given relating the sensitivity of the system to variations in muscle response and Golgi tendon organ (tension receptor) response. By considering the events taking place at synapses and end-plates during “isometric tension-small knee angle excursion” conditions as stationary stochastic processes, an external “noise” input to the system is given, whose spectrum is derived from the statistics of a shot-process representation of these events. The paper concludes with some correlations between the analytical results and clinical syndromes.     

Ethylene preparation and its application to physiological experiments

Ethylene is the first identified gaseous hormone regulating many aspects of plant growth and development. ACC and ethephon are two widely used chemicals replacing ethylene treatment when ethylene is not available. However, the amount of ethylene converted by ACC and ethephon is not controllable, leaving it questionable whether either treatment can mimic the effects of ethylene for experiments that are sensitive to ethylene concentration, response window, and treatment durations. Ethylene can be chemically made by ethanol dehydration; however, further purification from the dehydration products is needed. We previously reported that the ethylene gas can be easily prepared by decomposing ethephon in a buffered condition and the resulting ethylene can be used directly. Ethylene responses can be estimated by the measurement of the hypocotyl length of etiolated seedlings, or by ERF1 (Ethylene Response Factor1) expression. Although ACC of low concentrations is insufficient to induce ERF1 expression, ACC of high concentrations can replace ethylene for experiments where ethylene treatment is not feasible. However, ACC may undergo early consumption. Versatile approaches were developed so that laboratories lacking ethylene and techniques for gas handling can easily perform necessary ethylene treatments.Key words: ethylene preparation, ethephon, ACC     

A portable multi-channel recording system for analysis of acceleration and angular velocity in six dimension.

A portable recording system was developed for analysis of more than three analog signals collected in field works. Stereo audio recorder, available as consumer products, was made use for a core cornponent of the system. For the two tracks of recording, a multiplexed analog signal is stored on one track, and reference code on the other track. The reference code indicates the start of one cycle for multiplexing and swiching point of each channel. Multiplexed signal is playbacked and decoded with a reference of the code to reconstruct original profiles of the signal. Since commercial stereo recorders have cut DC component off, a fixed reference voltage is inserted in the sequence of multiplexing. Change of voltage at switching from the reference to the data channel is measured from playbacked signal to get the original data with its DC component. Movement of vehicles and human head were analyzed by the system. It was verified to be capable to record and analyze multi-channel signal at a sampling rate more than 10Hz.     

An industrial application of multiparameter flow cytometry: assessment of cell physiological state and its application to the study of microbial fermentations.

BACKGROUND: When using traditional microbiological techniques to monitor cell proliferation and viability, stressed, sublethally injured, or otherwise "viable but nonculturable" cells often go undetected. Because of this, such cells often are not considered by mathematical models used to predict bioprocess performance on scale-up and inaccuracies result. Therefore, analytical techniques, decoupled from postsampling growth, are desirable to rapidly monitor individual cell physiologic states during microbial fermentations. METHODS: Microbial cells, including Escherichia coli, Rhodococus sp., and Sacharomyces cerevisiae, were taken at various stages from a range of fermentation processes and stained with one of three mixtures of fluorescent stains: rhodamine 123/propidium iodide, bis-oxonol/propidium iodide, or bis-oxonol/ethidium bromide/propidium iodide. An individual cell's physiologic state was assessed with a Coulter Epics Elite analyzer based on the differential uptakes of these fluorescent stains. RESULTS: It was possible to resolve an individual cell's physiologic state beyond culturability based on the functionality of dye extrusion pumps and the presence or absence of an intact polarized cytoplasmic membrane, enabling assessment of population heterogeneity. This approach allows the simultaneous differentiation of at least four functional subpopulations in microbial populations. CONCLUSIONS: Fluorescent staining methods used in our laboratories have led to a functional classification of the physiological state of individual microbial cells based on reproductive activity, metabolic activity, and membrane integrity. We have used these techniques extensively for monitoring the stress responses of microorganisms in such diverse areas as bioremediation, biotransformation, food processing, and microbial fermentation; microbial fermentation is discussed in this article.     

An electrical recording soil moisture tensiometer

Summary An automatically recording soil moisture tensiometer was produced by substituting the usual mercury manometer by an electrical pressure transducer. Like other tensiometers and unlike the neutron probe, this instrument samples relatively small volumes of soil. In tests, individual recording tensiometers gave results repeatable to ± 0.002 bar even in moist soils and responded twice as quickly as standard tensiometers. As a result it has been possible to describe and automatically record events in a forest soil profile following a period of precipitation clearly identifying differences at 2 and 7 cm below ground level.     

Selector systems in recording physiological and behavioural activity in sedentary aquatic animals

The design and use of selector systems in recording physiological rate functions and behavioural activity in sessile invertebrates, particularly bivalves, is described for use in the laboratory and the field. The experimental limitations of the technique are discussed and the use of switch systems with other types of aktograph is described. Switch systems permit large groups of animals to be used in activity studies, whilst reducing both time spent in data handling and cost per animal of the recording system.     

An application of statistics to comparative metagenomics

Background  

Metagenomics, sequence analyses of genomic DNA isolated directly from the environments, can be used to identify organisms and model community dynamics of a particular ecosystem. Metagenomics also has the potential to identify significantly different metabolic potential in different environments.