Temperature Coefficients for the Oxidative Metabolic Responses to Electrical Stimulation in Cerebral Cortex

Temperature coefficients of both cat and toad brain have been calculated for the active metabolic state induced by electrical stimulation. Values are higher than most of the values previously reported for "rest" metabolism, whether calculated from Arrhenius plots or from linear graphs. Relative rates of oxidative metabolism were obtained by measuring the time course of the transient changes in NADH fluorescence and cytochrome aa3 absorption by reflectance techniques directly from the surface of the exposed cat cerebral cortex in vivo and from the isolated intact toad brain mounted in a cuvet. These findings demonstrate that such optical methods accurately record metabolic processes.     

Human Postural Responses to Vibratory Stimulation of Calf Muscles under Conditions of Visual Inversion

The authors studied postural responses to bilateral vibratory stimulation (70 Hz, 1 mm, 2 s) of the calf triceps proprioceptors or anterior tibial muscles. Anteroposterior body tilts evoked by vibration were recorded by stabilography. The authors compared the values of postural responses under various conditions of visual control, namely, with normal vision, eyes closed, right–left inversion of the visual space by prismatic spectacles, central vision, and diffuse light. Visual inversion influenced the subjects' proprioceptive postural responses. The amplitude of vibration-evoked shifts of the feet pressure center was minimal with eyes open and significantly increased with eyes closed and inverted vision. Postural responses with visual inversion were significantly stronger than with eyes closed. Since inversion spectacles enabled a subject to see only the central part of the visual field (20°), the reference point was the condition of central vision, i.e., spectacles with same visual angle and without prisms. Postural responses were significantly weaker under these conditions than with visual inversion and eyes closed. Visual field inversion by prismatic spectacles made it impossible to use visual information for stabilizing the human upright posture and, moreover, destabized it. True, this holds only for a randomized experimental protocol, which prevents adaptation to prisms.     

OMR-Arena: Automated Measurement and Stimulation System to Determine Mouse Visual Thresholds Based on Optomotor Responses

Measurement of the optomotor response is a common way to determine thresholds of the visual system in animals. Particularly in mice, it is frequently used to characterize the visual performance of different genetically modified strains or to test the effect of various drugs on visual performance. Several methods have been developed to facilitate the presentation of stimuli using computer screens or projectors. Common methods are either based on the measurement of eye movement during optokinetic reflex behavior or rely on the measurement of head and/or body-movements during optomotor responses. Eye-movements can easily and objectively be quantified, but their measurement requires invasive fixation of the animals. Head movements can be observed in freely moving animals, but until now depended on the judgment of a human observer who reported the counted tracking movements of the animal during an experiment. In this study we present a novel measurement and stimulation system based on open source building plans and software. This system presents appropriate 360 stimuli while simultaneously video-tracking the animal''s head-movements without fixation. The on-line determined head gaze is used to adjust the stimulus to the head position, as well as to automatically calculate visual acuity. Exemplary, we show that automatically measured visual response curves of mice match the results obtained by a human observer very well. The spatial acuity thresholds yielded by the automatic analysis are also consistent with the human observer approach and with published results. Hence, OMR-arena provides an affordable, convenient and objective way to measure mouse visual performance.     

神经元对于高频电刺激的动态响应

深部脑刺激(deep brain stimulation,DBS)在许多神经系统疾病的临床治疗上都展现出良好的应用前景,然而,其作用机制尚不明确.常规DBS采用高频刺激(high frequency stimulation,HFS)的脉冲序列,这种窄脉冲最容易激活神经元结构中的轴突部分,通过轴突的投射,将HFS的作用传播至下游神经元.因此,为了探讨DBS的作用机制,并鉴于海马脑区是治疗癫痫和痴呆症等疾病的重要靶点,我们研究了海马区轴突HFS对于下游神经元的作用.对麻醉大鼠的海马CA1区传入神经通路Schaffer侧支施加1 min的100 Hz高频刺激,记录并提取下游CA1区锥体神经元和中间神经元的单元锋电位.计算锋电位的发放率,以及它们与刺激脉冲之间的锁相值(phase-locking value,PLV)和潜伏期,以定量分析HFS期间神经元动作电位发放的变化趋势.结果显示,在传入轴突上施加HFS时,初期会诱发下游神经元群体同步产生动作电位(即群峰电位).在HFS后期(群峰电位消失之后),两类神经元的单元锋电位发放仍然持续,并且发放率较稳定.但是,锋电位与刺激脉冲之间的锁相性逐渐减弱、潜伏期逐渐延长.而且,与中间神经元相比较,锥体神经元锋电位的锁相性更弱、潜伏期更长.这些结果表明,持续的轴突HFS可以诱导下游神经元产生非同步的活动,高频脉冲刺激引起的不完全轴突传导阻滞可能是导致该现象产生的主要原因.本文的研究为揭示脑刺激的作用机制提供了重要信息.     

植物对机械刺激的响应及信号转导

机械刺激是一种广泛存在但却长期被忽视的环境胁迫因子。由于其营固于土壤的生活习性,植物在其整个生命过程中都不同程度地遭受着机械刺激的胁迫,它影响着植物的生长发育、形态建成、抗逆性的形成等。本文结合我们实验室的研究成果及国内外的研究进展,综述了植物对机械刺激的响应、机械刺激在细胞内诱发的信号事件、各种信号之间的信号交谈及基因表达,并对未来的研究方向提出了展望。     

Temperature Asymmetry of the Rat Cerebral Hemispheres

The field potential and temperature of the cerebral cortex were studied in right-handed, left-handed, and ambidextrous rats. Temperature asymmetry of the cerebral hemispheres was revealed, which proved to differ in rats with different types of interhemispheric asymmetry: the interhemispheric temperature gradient was maximal in left-handed rats, minimal in right-handed rats, and intermediate in ambidextrous rats. Both parameters of energy metabolism (field potential and temperature of the cerebral cortex) correlated with one another, and the structure of these statistically significant correlations was different in right-handed, left-handed, and ambidextrous rats. It is suggested that the previously known types of interhemispheric asymmetry—biochemical, neurophysiological, and organoelement—are based on differences in the intensity of energy-consuming processes in the cerebral hemispheres.     

Postural Responses Evoked by Vibrational Stimulation of the Shin Muscles under Conditions of Virtual Visual Environment

We studied the effects of unexpected shifts of the visually perceived artificial surroundings (virtual visual environment, VVE) on postural reactions evoked by vibrational stimulation of proprioceptors of the shin muscles; tests were performed in a standing position of the subject. The VVE possessed two planes, a mobile foreground, whose displacements correlated with oscillations of the body, and a stationary background. The subjects were asked to use the latter as a reference system in corrections of the posture. The VVE parameters were controlled by a computer; shifts of the VVE foreground were combined with similar, in their duration and profile, stimulation-evoked displacements of the body. Despite the fact that the subjects had a possibility to use the stationary background as the reference system, the magnitudes of the evoked postural responses under conditions of perception of the VVE significantly exceeded the respective magnitudes upon standing with the eyes open in front of a completely stationary visual image. Postural responses progressively increased with increases in relative values of the shifts of the VVE foreground but always remained smaller than the responses under conditions of testing with the eyes closed. Augmentation of the postural responses at a synphase pattern of interrelations between the body movements and VVE shifts was more significant than at antiphase relations. Thus, shifts of the VVE foreground, on the one hand, destabilized the maintenance of the vertical posture, which resulted in intensification of the postural responses. On the other hand, such shifts allowed the subject to use them as feedback signals and to modulate the magnitude of postural responses when there was a change in the direction of interrelations between the body movements and the perceived visual image.     

Conditioned Avoidance Responses to the Pain Stimulation of Another Animal

One of the more intriguing findings in recent animal research is the evidence that lower animals (rats, dogs) can act "altruistically." Such altruism is claimed for situations in which an animal will learn a response that has no direct effect on it-self, but removes another of its species from pain. This phenomenon has been of great interest to P. V. Simonov, one of the authors of this study, because of his wider interests in problems of the role of emotions and motives in animals and man.     

RNA Species during Visual Stimulation

AS part of a programme concerned with the quality of RNA synthesized during behaviour we have carried out an experiment to detect the synthesis of qualitatively unique species of RNA during visual stimulation. Two litters of male Wistar rats were housed in a dimly lit room from 40 days of age. At 100 days four members of each litter were injected intracran-ially with 1 mCi of 5-³H-uridine and after 30 min were subjected to 90 min of visual stimulation (experimental subjects), while other rats of each litter were restrained in darkness (control subjects).     

Asymmetry of Diacylglycerol Metabolism in Rat Cerebral Hemispheres

Diacylglycerols (DGs) were found to be asymmetrically distributed between the two cerebral hemispheres of rat brain. The left cerebral hemisphere (LCH) contained 100% more DG than the right cerebral hemisphere (RCH). The lateralization was enhanced in animals subjected to depolarization induced by a single electroconvulsive shock (ECS). During the acute phase of the convulsion, the DG pool increased in both hemispheres, with the LCH attaining a concentration 180% higher than the RCH. Stearate and arachidonate were the principal DG-acyl groups accumulated in the RCH, whereas in the LCH stearate and palmitate were mainly involved. After the last of a series of five shocks (one per day) the lateralization of the "DG response" was less accentuated during the acute phase of the ECS. Whereas DG release was drastically reduced in the LCH, in the RCH it was minimally affected. The DG sidedness after five shocks was nevertheless maintained at the level of arachidonate-containing DGs, which showed a higher accumulation in the LCH than in the RCH. The kinetics of DG removal showed a rapid phase during the first minute following a single or five ECSs. Total DG levels returned to basal values in the RCH, whereas in the LCH they remained slightly increased with respect to the initial levels 1 min after the convulsive episode. Minimal changes occurred in the subsequent 4 min. Chronic ECS altered the endogenous DG content and composition. Thus, 24 h after the last of four ECSs, total levels of DGs diminished by 40% in the RCH, whereas they remained unchanged in the LCH.(ABSTRACT TRUNCATED AT 250 WORDS)     

大鼠海马神经元对于高频脉冲刺激的暂态响应

闭环刺激是深部脑刺激(deep brain stimulation,DBS)的重要发展方向之一,有望用于治疗多种脑神经系统疾病.与常规开环的长时间持续刺激不同,闭环刺激通常采用短促的高频脉冲序列.而神经元对于高频刺激的响应存在暂态过程,在初期的短时间内会发生很大变化,从而影响闭环刺激的作用.为了研究这种暂态过程,在大鼠...     

Some Responses of Tsetse Flies to Visual and Olfactory Stimuli

HISTOCHEMICAL fluorescence experiments, using the modifications^1,2 of the formaldehyde condensation procedure described by Falck et al.³, are increasingly common. The procedures for demonstrating monoamines in freeze-dried tissue, require that the sections cut from formaldehyde gas-treated tissue be kept away from water and so the conventional heated water bath for relaxing the cut paraffin sections cannot be used. Acetonitrile⁴ and liquid paraffin⁵ have been utilized and some laboratories even use a heated mercury bath (S. Norr, personal communication), although what is desired is a very non-reactive liquid. ‘Fluorinert Electronic Liquids FC-75, FC-77’ (3M Company, St Paul, Minnesota 55101) adequately replace the water bath. At 45° C these two clear liquids allow cut sections to be handled in the same manner as in the conventional water bath. Other liquids in this series can probably be chosen to give similar characteristics at other bath temperatures, although they have not been tried. A bath with intermediate qualities could be made as the liquids in the series are completely miscible with one another. The ‘Fluorinert Electronic Liquids’ are stated by their manufacturer to be very non-reactive and to have very low water and oil solubilities. The inertness of these liquids suggests that they may also be used to float sections as they are cut and to immerse freeze-dried tissue for storage.     

Chemosensory Responses of Acanthamoeba castellanii: Visual Analysis of Random Movement and Responses to Chemical Signals

A visual assay slide chamber was used in conjunction with time-lapse videomicroscopy to analyze chemotactic behavior of axenically grown Acanthamoeba castellanii. Data were collected and analyzed as vector scatter diagrams and cell tracks. Amebas responded to a variety of bacterial products or potential bacterial products by moving actively toward the attractant. Responses to the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (fMLP), lipopolysaccharide, and lipid A were statistically significant (P≤ 0.03), as was the response to fMLP benzylamide (P≤ 0.05). Significant responses to cyclic AMP, lipoteichoic acid, and N-acetyl glucosamine were also found. Chemotactic peptide antagonists, mannose, mannosylated bovine serum albumin, and N-acetyl muramic acid all yielded nonsignificant responses (P > 0.05). There was no single optimal concentration for response to any of the attractants tested, and amebas responded equally over the range of concentrations tested. Pretreatment of amebas with chemotactic peptides, bacterial products, and bacteria reduced the directional response to attractants. Amebas that had been grown in the presence of bacteria appeared more responsive to chemotactic peptides. Treatment of amebas with trypsin reduced the response of cells to chemotactic peptides, though sensitivity was restored within a couple of hours. This suggests the ameba membrane may have receptors, sensitive to these bacterial substances, which are different from the mannose receptors involved in binding bacteria to the membrane during phagocytosis. The rate of movement was relatively constant (ca. 0.40 μm/s), indicating that the locomotor response to these signals is a taxis, or possibly a klinokinesis, but not an orthokinesis. Studies of the population diffusion rate in the absence of signals indicate that the basic population motility follows the pattern of a Levy walk, rather than the more familiar Gaussian diffusion. This suggests that the usual mathematical models of ameboid dispersion may need to be modified.     

Roles of Adenylate Cyclases in Ciliary Responses of Paramecium to Mechanical Stimulation

Paramecium shows rapid forward swimming due to increased beat frequency of cilia in normal (forward swimming) direction in response to various kinds of stimuli applied to the cell surface that cause K⁺‐outflow accompanied by a membrane hyperpolarization. Some adenylate cyclases are known to be functional K⁺ channels in the membrane. Using gene‐specific knockdown methods, we examined nine paralogues of adenylate cyclases in P. tetraurelia to ascertain whether and how they are involved in the mechanical stimulus‐induced hyperpolarization‐coupled acceleration of forward swimming. Results demonstrated that knockdown of the adenylate cyclase 1 (ac1)‐gene and 2 (ac2)‐gene inhibited the acceleration of forward swimming in response to mechanical stimulation of the cell, whereas that spared the acceleration response to external application of 8‐Br‐cAMP and dilution of extracellular [K⁺] induced hyperpolarization. Electrophysiological examination of the knockdown cells revealed that the hyperpolarization‐activated inward K⁺ current is smaller than that of a normal cell. Our results suggest that AC1 and AC2 are involved in the mechanical stimulus‐induced acceleration of ciliary beat in Paramecium.     

Left-Right Asymmetry Is Required for the Habenulae to Respond to Both Visual and Olfactory Stimuli

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雄性大熊猫对化学信息行为反应的年龄差异

化学通讯对哺乳动物的生存和繁殖起着重要作用。研究了雄性大熊猫(Ailuropoda melanoleuca)对同伴个体尿液气味行为反应的发育模式。结果显示,在成年雌性个体的尿液气味刺激下,雄性个体表现显著多的嗅闻行为和嗅闻/舔舐环境行为,但是嘶咬气味刺激物的行为明显减少。在雌性个体的尿液气味刺激下,不同年龄段的雄性个体行为表现不同,成年雄性个体表现较亚成年和幼年个体显著多的舔舐行为。此外,成年个体和亚成年个体均表现较多的嗅闻/舔舐环境行为,而幼年个体则无该行为表现。幼年个体较成年和亚成年个体表现显著多的气味涂抹行为,而且嘶咬气味刺激物的时间较亚成年个体显著多。幼年个体和亚成年个体对雌性和雄性个体尿液气味刺激的行为反应不存在显著差异。研究结果表明,雄性大熊猫对同种个体尿液中化学信息的行为反应呈现出年龄差异。