蜜蜂下行神经元的光谱特性

利用生理细胞外记录方法研究了蜜蜂下行神经元的光谱敏感特性,不同波长的单色光刺激引起的给先反应和撤光反应的相对强度不同．分析了３７例下行神经元的光谱敏感特性,发现下行神经元有的是光谱宽带和多光谱性的,有的是光谱窄带,给光和撤光反应都具有不同的最敏感区。     

不同的声音强度对大鼠听皮层神经元特征频率可塑性的影响

目的：探讨声音强度对大鼠听皮层神经元特征频率可塑性的影响。方法：采用常规电生理学细胞外记录技术,测定不同声刺激强度下,听皮层神经元的特征频率和调谐曲线,比较条件刺激前后的变化。结果：在条件刺激声频率和神经元的特征频率相差±1.0kHz范围内,条件刺激诱导的神经元特征频率可塑性与条件刺激强度有关,较高的刺激强度比较低刺激强度诱导的特征频率可塑性概率高;特征频率可塑性的概率与神经元的频率调谐曲线类型相关,但这种相关几乎不受条件刺激声强度影响。结论：条件声刺激强度可明显影响大鼠听皮层神经元特征频率的可塑性。     

神经电生理信号多道同步采集和分析系统

单细胞多点同步记录技术在国内外已经被广泛应用,但在国内仍缺乏与国产或日产细胞电生理记录仪器相匹配的多通道同步生物电信号采集与分析系统。本文介绍了新近研制的可进行双通道甚至晚多通道细胞电生理信号采集的神经细胞电生理信号采集与分析系统,及其关键技术及实现方法和应用实例。     

蜜蜂下行神经元的光反应特征

利用电生理细胞外记录方法研究了蜜蜂下行神经元对光的反应特征以及与水平方向上光刺激角度的关系。 光刺激主要引起下行神经元的给光反应和撤光反应,持续性反应很弱。下行神经元的反应依赖于光刺激强度,在一定的强度范围内,随着光强度增大,反应强度也增大根据改变刺激角度引起的反应,在水平方向上最敏感,张角最大,约大于40°。     

An experimental study of the forms of complexly organized nonautomatized activities in cats in free behavior

Modification is proposed of the method of "pair presentations with transfer" for the purpose of studying of some forms of animals complex behaviour in chronic experiment. The experiments were conducted on cats in the apparatus, the limited size of which make possible simultaneous recording of electrophysiological characteristics of the brain activity. On the basis of experimental data it is postulated that "reflex to relation" is one of the most complex reflexes of the animal including, alongside with conditioned component, elements of non-automatized behaviour. The proposed method can be used in neurophysiological, electrophysiological and neuropharmacological experiments on animals.     

小鼠胚胎心肌细胞的分离及电生理特性

本文旨在探索小鼠胚胎心肌细胞的分离方法并观察其电生理特性。应用胶原酶B消化法获得不同时期单个小鼠胚胎心肌细胞;利用全细胞膜片钳技术,记录胚胎心肌细胞的超极化激活的非选择性内向阳离子电流(If)和L-钙电流(ICa-L),并用电流钳记录其自发性动作电位。胚胎心肌细胞通过相差显微镜依据其形态和自发性收缩进行鉴定。本法分离所获得的胚胎心肌细胞容易进行全细胞膜片钳记录,可用于记录If,ICa-L．电流和自发性动作电位,己证实胚胎心肌细胞If和Ica-L的电生理特性与成年起搏细胞或心肌细胞相似。本实验建立的分离方法简单、稳定、有效、可靠,最早可获得8．5d的胚胎心肌细胞。胚胎心肌细胞的电生理记录为探索胚胎心肌细胞的电生理特性提供了一个可用的模型,并可能为某些心脏疾病产生的机制提供实验依据。     

大鼠皮质脊髓束神经电信号的记录与分析方法研究

目的：探索皮质脊髓束（CST）电生理信号的采集记录方法,分析描述电信号的特征,从而为通过植入式微电极阵列进行信号采集的记录方法建立一定的实验基础,为将来进一步研究脊髓损伤修复与功能重建提供有价值的神经电生理基础资料。方法：使用神经信号采集处理系统（Cerebus System）,在SD大鼠的脊髓T8节段处的皮质脊髓束内通过插入微电极,记录大鼠皮质脊髓束神经电信号。利用神经信号分析软件Offline Sorter、Neuroexplorer对已存储的信号文件进行波形特点的描述,包括波长、波幅、放电频率、同一电极上记录到的不同放电单元之间的同步性、两根电极上记录到的不同放电单元之间的同步性、放电信号的峰间期（ISI）分析等。结果：长时间稳定记录到连续的皮质脊髓束自发放电信号,一般在同一电极上记录到3~4个来自不同放电单位（细胞）的放电信号。皮质脊髓束自发放电信号的波形呈双向型,波宽为0.6~1.3 ms,波幅为百μV级。在多次实验状态下均能达到很高的信噪比,信号采集效果理想。经快蓝（LFB）染色确认记录电极尖端位于皮质脊髓束内。结论：本实验采用Cere-bus神经信号采集处理系统,利用记录电极可在大鼠的皮质脊髓束内较长时间稳定地记录到较为稳定的微伏级神经电信号,并可进行有意义的神经电信号特征分析,为进一步研究脊髓损伤修复与功能重建提供了有价值的神经电生理基础资料。     

Single-channel recording of ligand-gated ion channels

Electrophysiological recording of single-channel currents is the most direct method available for obtaining detailed and precise information about the kinetic behavior of ion channels. A wide variety of cell types can be used for single-channel recording, but to obtain the highest resolution of the briefest channel opening and closing events, low-noise recordings, coupled with a minimal filtering frequency, are required. Here, we present a protocol designed to help those with some electrophysiological expertise who wish to explore the properties of native and recombinant single ligand-gated ion channels. We have focused on the practical aspects of recording single GABA channels from cell-attached and outside-out patches and also introduced some of the preliminary considerations that are necessary for the analysis of single-channel data, including an introduction to single-channel analysis software.     

Caspase-3 activity in the rat hippocampal slices reflects changes in synaptic plasticity

Considering the involvement of caspase-3 in neuronal plasticity, we studied caspase-3 activity in the rat hippocampal slices, and electrophysiological characteristics of extracellular responses to paired-pulse stimulation of Schaffer's collaterals in the CA1 subfield of hippocampus. Caspase-3 activity was measured after electrophysiological recording in each slice separately. Maximal caspase-3 activity was observed in the slices with low responsiveness to single afferent stimulation indicative of decreased efficacy of interneuronal interaction. This phenomenon is unrelated to depression of neuronal excitability since paired-pulse stimulation increases the synaptic efficacy to second stimulus thus restoring population spike amplitudes to normal values. In "damaged" slices with impaired spike generation up to disappearing spikes to both stimuli, caspase-3 activity was close to the normal level of the "healthy" slices. The activity of another proteinase, cathepsin B, was increased in the "damaged" slices, no correlation with the modifications of electrophysiological indices being detected. Our data suggest that high caspase-3 activity in hippocampal slices is involved in maintenance of synaptic plasticity but not necessarily related to apoptosis.     

Sensory systems

Our understanding of sensory systems has grown impressively in recent years as a result of intense efforts to characterize the mechanisms underlying perception. A large body of evidence has accrued regarding the processes through which sensory information at the biochemical, electrophysiological, and systems levels contributes to the conscious experience of a stimulus. Our efforts to understand the function of sensory systems have been aided by the development of new techniques, including powerful methods of molecular biology, refined short- and long-term approaches to recording from single and multiple neurons, and non-invasive neuroimaging techniques that allow us to study activity within the human brain while subjects perform a variety of cognitive tasks. In future research, the last approach is likely to form a bridge between the large body of electrophysiological knowledge acquired in animal experiments and that currently being obtained in human imaging research.     

Blind patch clamp recordings in embryonic and adult mammalian brain slices

To obtain electrophysiological recordings in brain slices, sophisticated and expensive pieces of equipment can be used. However, costly microscope equipment with infrared differential interference contrast optics is not always necessary or even desirable. For instance, obtaining a randomized unbiased sample in a given preparation would be better accomplished if cells were not directly visualized before recording. In addition, some preparations require thick slices, and direct visualization is not possible. Here we describe a protocol for the 'blind patch clamp method' that we developed several years ago to perform electrophysiological recordings in mammalian brain slices using a standard patch clamp amplifier, dissecting microscope and recording chamber. Overall, it takes approximately 3-4 h to set up this procedure.     

Objective and subjective indexes of auditory motion processing

The objective and subjective indexes of sound stimulus discrimination have been studied in order to get insight into individual stages of signal processing in the human brain. The experiment employed two methods: electrophysiological (mismatch negativity or MMN recording) and psychophysical (two-alternative forced choice). Two types of spatial sound stimuli simulated gradual and abrupt sound motion from the head midline. The subjective discrimination between the gradual and abrupt motions was estimated as a function of the stimulus trajectory length. MMN as an objective index of spatial discrimination has been obtained in response to the subthreshold and the suprathreshold levels of psychophysical discrimination. An increase in the angular displacement of the moving stimuli resulted in an increase in both the MMN amplitude and the subjective discrimination, although their correlation remained below the significance level. The results obtained are discussed from the point of view of preconscious perception of auditory spatial information.     

Effects of artificial and natural diets on success in tip recording and on galeal chemosensillum morphology of European Corn Borer larvae

Abstract. Larvae of Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae) were reared on artificial diet, fresh cut corn, or switched from diet to corn for 5 days prior to tip recording. Electrophysiological responses to a standard mixed chemical stimulus were obtained from the galeal uniporous chemosensilla of the early fifth-stadium larvae. Mouthparts of some larvae were briefly treated with protease, then recorded again. Larvae were then processed for scanning electron microscopy (SEM) of chemosensilla terminal pores. Spike:noise ratios were significantly higher for corn-reared, switched-to-corn, and protease- treated larvae, relative to diet-reared larvae. Morphology of the chemo- sensilla terminal pores, as assessed by SEM, reveals that apparent occlusion of the pore tip is significantly greater for diet-reared larvae relative to the other groups. The data suggest an association between quality of the electrophysiological recordings and physical blockage of the terminal sensillum pore. These data should serve as a caveat for those engaged in chemosensory studies of insect herbivores.     

An interplexiform cell in the goldfish retina: light-evked response pattern and intracellular staining with horseradish peroxidase

Summary The light-evoked response pattern and morphology of one interplexiform cell were studied in the goldfish retina by intracellular recording and staining. The membrane potential of the cell spontaneously oscillated in the dark. In response to a brief light stimulus, the membrane potential initially gave a slow transient depolarization. During maintained light, the oscillations showed a tendency to be suppressed; the response of the cell to the offset of the stimulus was not so prominent. The perikaryon of the interplexiform cell was positioned at the proximal boundary of the inner nuclear layer. The cell had two broad layers of dendrites; one was diffuse in the inner plexiform layer, the other was more sparse in the outer plexiform layer. The morphological and electrophysiological characteristics of the cell are discussed in relation to dopaminergic interplexiform cells and the light-evoked release pattern of dopamine in the teleost retina.     

Functional verification of pulse frequency modulation-based image sensor for retinal prosthesis by in vitro electrophysiological experiments using frog retina

The functioning of a 16 x 16 pixel pulse frequency modulation (PFM) image sensor for retinal prosthesis is verified through in vitro electrophysiological experiments using detached frog retinas. This image sensor is a prototype for demonstrating the application to in vitro electrophysiological experiments. Each pixel of the image sensor consists of a pulse generator (PFM photosensor), a stimulus circuit, and a stimulus electrode (Al bonding pad). The image sensor is fabricated using standard 0.6 microm CMOS technology. For in vitro electrophysiological experiments, a Pt/Au stacked electrode is formed on the Al bonding pad of each pixel and the entire sensor is fixed in epoxy resin. The PFM image sensor is confirmed experimentally to provide electrical stimulus to the retinal cells in a detached frog retina.     

Quantifying exocytosis by combination of membrane capacitance measurements and total internal reflection fluorescence microscopy in chromaffin cells

Total internal reflection fluorescence microscopy (TIRF-Microscopy) allows the observation of individual secretory vesicles in real-time during exocytosis. In contrast to electrophysiological methods, such as membrane capacitance recording or carbon fiber amperometry, TIRF-Microscopy also enables the observation of vesicles as they reside close to the plasma membrane prior to fusion. However, TIRF-Microscopy is limited to the visualization of vesicles that are located near the membrane attached to the glass coverslip on which the cell grows. This has raised concerns as to whether exocytosis measured with TIRF-Microscopy is comparable to global secretion of the cell measured with membrane capacitance recording. Here we address this concern by combining TIRF-Microscopy and membrane capacitance recording to quantify exocytosis from adrenal chromaffin cells. We found that secretion measured with TIRF-Microscopy is representative of the overall secretion of the cells, thereby validating for the first time the TIRF method as a measure of secretion. Furthermore, the combination of these two techniques provides a new tool for investigating the molecular mechanism of synaptic transmission with combined electrophysiological and imaging techniques.     

Analysis of Possible Involvement of Local Bioelectric Responses in Chilling Perception by Higher Plants Exemplified by <Emphasis Type="Italic">Cucurbita pepo</Emphasis>

Macroelectrodes and electrophysiological setup were used in experiments with stems of 15-day-old pumpkin (Cucurbita pepo L.) seedlings for computer-assisted data recording. It is shown that local bioelectric responses induced by graded local chilling are similar to the receptor potentials of animals. These responses increase gradually with stimulus strength and trigger the action potential generation when a temperature threshold is attained. The excitation threshold of cells in seedling stems displays the phenomenon of accommodation. Parameters of local bioelectric responses induced by intermittent cooling can undergo changes similar to sensitization-habituation patterns. The results indicate that local electrical responses may be involved in early stages of cooling perception in cells of higher plants devoid of locomotive functions.     

Inference about a change point in experimental neurophysiology

When recording the electrical discharge of single neurons, two questions arise: (1) Does this activity represent changes related to some event of the experiment (for instance, a stimulus)? (2) What is the mean latency time between this event and the change of activity? We propose statistical tools for answering these questions based on the estimation of a change point, for which we have developed a new method. This method selects the most clear-cut change when other changes exist.