共查询到20条相似文献，搜索用时 15 毫秒
1.
Single neurons in the midbrain tegmentum of rats showed clear discriminatory responses to three tones announcing either food or water or no reinforcement. Subjects were required to press a single lever and remain motionless for 2 seconds during which time unit activity from several brain sites was recorded. One of the tones, randomly designated, was sounded halfway through this period. Manipulation of drive states revealed that the highest activity was associated with tones announcing the reinforcement for which the animal was most strongly motivated. Thus, from a hungry animal sustained or increased firing rates were elicited by a " food" tone and differentially lowered rates by the other tones. 相似文献
2.
Recurrent facilitation in the cat's spinal cord has been studied in deep peroneal and quadriceps motoneurons with the use of intracellular recording. The presence of facilitation was indicated by several criteria, among them increased firing index of the cells or decreased latency of firing. In many, but not all, facilitated cells the conditioning volley caused a small visible depolarization. Subthreshold synaptic potentials were frequently increased in magnitude by the conditioning volley, which also increased the effectiveness of a stimulus applied through the microelectrode. Facilitation was found in a large percentage of the motoneurons investigated and was clearly able to bring about pronounced changes in the excitability and firing behavior of these cells. 相似文献
3.
Operant conditioning of cortical unit activity 总被引：6，自引：0，他引：6
E E Fetz 《Science (New York, N.Y.)》1969,163(870):955-958
The activity of single neurons in precentral cortex of unanesthetized monkeys (Macaca mulatta) was conditioned by reinforcing high rates of neuronal discharge with delivery of a food pellet. Auditory or visual feedback of unit firing rates was usually provided in addition to food reinforcement. After several training sessions, monkeys could increase the activity of newly isolated cells by 50 to 500 percent above rates before reinforcement. 相似文献
4.
Extracellular action potentials were recorded from units in the preoptic area of the brain of the Australian blue-tongued skink (Tiliqua scincoides) during periods of local heating and cooling of the brain (20 degrees to 36 degrees C) with water-perfused thermodes. In this temperature range most spontaneously firing neurons were temperature-insensitive, but eight showed sensitivity to the thermal stimulus. Five warm neurons increased their activity when the brain temperature was raised, and three cold neurons showed increased activity with fall in temperature. 相似文献
5.
[目的]探讨中华蟾蜍(Bufo bufo gargarizans)胚后嗅球神经元自发电活的电生理学特性的发育变化。[方法]应用微电极电生理技术,对中华蟾蜍胚后嗅球神经元的自发放电活动进行在体胞外记录。[结果]随着嗅球的发育,其神经元的放电形式逐渐增多,单个放电振幅逐渐增大,且在变态期达最大;连续放电振幅在胚后发育的中期变化不大,但高于发育的早期和成体期;连续簇状放电频率随着发育时期而降低,但在成体期再次升高,而连续单个放电频率只在成体期增大。[结论]随着嗅球的发育,神经元的兴奋性逐步提高,神经元电活动形式逐渐呈现多样化。 相似文献
6.
公猪在一次完整射精过程中有1至数次不等的短暂停顿,将公猪一次完整射精的精液分成三段:浓精(S1)、第一次射精中除浓精外的精液(S2)及其余部分精液(S3),研究三段精液精子密度、精液量的变化规律。结果表明:浓精精液量显著低于其它两段精液(P<0.01),而精子密度及总精子数显著高于其它两段精液(P<0.01);浓精量只占总精液量的约17%,而精子数占总精子数的约71%;公猪完整射精过程中的第一次射精精液量占总精液量的约70%、精子数占总精子数的约95%。 相似文献
7.
Mukamel R Gelbard H Arieli A Hasson U Fried I Malach R 《Science (New York, N.Y.)》2005,309(5736):951-954
Functional magnetic resonance imaging (fMRI) is an important tool for investigating human brain function, but the relationship between the hemodynamically based fMRI signals in the human brain and the underlying neuronal activity is unclear. We recorded single unit activity and local field potentials in auditory cortex of two neurosurgical patients and compared them with the fMRI signals of 11 healthy subjects during presentation of an identical movie segment. The predicted fMRI signals derived from single units and the measured fMRI signals from auditory cortex showed a highly significant correlation (r = 0.75, P < 10(-47)). Thus, fMRI signals can provide a reliable measure of the firing rate of human cortical neurons. 相似文献
8.
Norepinephrine-containing neurons: changes in spontaneous discharge patterns during sleeping and waking 总被引：2，自引：0，他引：2
Norepinephrine-containing neurons of the locus coeruleus of the cat were recorded with microelectrodes during unrestrained sleeping and waking. The recorded neurons were subsequently defined by combined fluorescence histochemistry of catecholamines and production of microlesions at recording sites. These pontine units show homogeneous changes in discharge patterns with respect to sleep stages, firing slowly during drowsy periods and slow wave sleep and firing in rapid bursts during paradoxical sleep. These data provide a direct correlation between the activity of defined catecholamine-containing neurons and the spontaneous occurrence of sleep stages. 相似文献
9.
对研究路段做了的钻孔勘察、土工原位试验和取代表性试样的室内试验，对土的物理性质、力学性能、压缩固结等主要指标进行了分析。结果表明：该路段上部土层分布不均匀，厚度变化大，密实性差，天然孔隙比大，且天然含水量较高。因此，必须对该路段进行有效的地基加固处理。本次的分析研究为该路段地基进行加固处理提供了参考依据。 相似文献
10.
分析了玻璃纤维长度和掺入量对水泥土抗压和抗拉强度和影响机理,试验结果表明,在考察范围内水泥土的强度随着玻璃纤维长度和掺入量的增加而增大,且玻璃纤维掺量对水泥土抗拉强度的影响比抗压强度更显著,但当玻璃纤维掺入量超过一定限度时,水泥土的强度反而会降低。 相似文献
11.
根据工程实际情况,应用真空井点降水联合加固软土地基的施工方法,通过施工沉降观测和理论分析,对真空井点降水联合预压加固软土地基的施工技术及加固有效深度、有效应力的变化问题进行了研究。验证了真空井点降水联合预压加固施工方法在寒区环境的适用性,分析了在该条件下,本施工方法的加固效果和沉降变化规律,为基础设计和工程施工提供参考依据。 相似文献
12.
Single olfactory bulb units were studied in two macrosmatic species of rodents under conditions intended to preserve the cyclical stimulation which normally accompanies nasal breathing. Patterns of unit activity related to the inhalation cycle were observed in all animals, often in the absence of specific stimuli, and could not be explained in simple mechanical terms. Distinctive changes in these patterns occurred in response to certain odors, and were generally independent of changes in the overall firing frequency. These findings indicate that a change in the overall firing frequency of unit discharges is neither a necessary nor sufficient measure of responsiveness to odors in the rodent olfactory bulb, and that stimulus-specific temporal distributions of unit firing may be involved in olfacto-endocrine activities. 相似文献
13.
竹屑粉UF基复合材料的制备及其力学性能研究 总被引：2，自引：0，他引：2
制备了一种竹屑粉脲醛树脂（UF）基复合材料,并对其性能特点进行了研究;介绍了UF基竹屑粉复合材料的制备方法。实验指出：竹屑粉UF基复合材料中的竹屑粉含量和粒度对性能有明显的影响,合理控制竹屑粉的粒度和分散度能使竹屑粉UF基复合材料取得较好的性能。 相似文献
14.
[目的]探讨东北小鲵（ Hynobius leechii）端脑发生与发育的电生理学特性。[方法]应用微电极电生理技术,对东北小鲵端脑发生和发育不同时期的自发电活动进行在体胞外记录。[结果]东北小鲵端脑发生和发育各时期自发放电形式共有单个放电、连续单个放电、簇状放电、连续簇状放电和不规则放电五种形式。端脑的发生阶段为3种,以单个放电和连续单个放电为主,记录到少数簇状放电;端脑的发育阶段为5种,以单个放电为主。随着端脑发生和发育的进行,胞外放电幅度逐渐提高,放电持续时间增加,放电频率加快,并于成体期达到最大;单个放电时程逐渐缩短;其它放电形式伴随发生发育过程相继出现。[结论]随着东北小鲵端脑发生与发育,神经元的兴奋性逐步提高,神经元电活动形式逐渐多样化。 相似文献
15.
Dopamine modulation of the effects of gamma-aminobutyric acid on substantia nigra pars reticulata neurons 总被引：2，自引：0，他引：2
Studies were conducted to assess whether basal ganglia output neurons originating in the substantia nigra pars reticulata might be affected by dopamine released from dendrites of neighboring substantia nigra pars compacta neurons. Dopamine applied by iontophoresis increased the baseline firing rates of approximately half of the substantia nigra pars reticulata cells tested. The more significant finding, unrelated to the increase in firing, was the ability of dopamine to attenuate the inhibitory responses of these cells to iontophoretically applied gamma-aminobutyric acid. These findings suggest a role for dopamine as a neuromodulator and further suggest that it can act at sites beyond the striatum to modify transmission from the basal ganglia to motor nuclei. 相似文献
16.
Grid cells in parahippocampal cortices fire at vertices of a periodic triangular grid that spans the entire recording environment. Such precise neural computations in space have been proposed to emerge from equally precise temporal oscillations within cells or within the local neural circuitry. We found that grid-like firing patterns in the entorhinal cortex vanished when theta oscillations were reduced after intraseptal lidocaine infusions in rats. Other spatially modulated cells in the same cortical region and place cells in the hippocampus retained their spatial firing patterns to a larger extent during these periods without well-organized oscillatory neuronal activity. Precisely timed neural activity within single cells or local networks is thus required for periodic spatial firing but not for single place fields. 相似文献
17.
针对传统低剪力墙延性的不足,提出了一种改进方案.为了准确把握新型配筋方案的优势,共完成了两片低剪力墙的低周反复加载试验,考察了它们在往复荷载作用下的极限承载力性能、滞回特性、延性以及破坏特征等.以试验研究为基础,采用ABAQUS有限元分析软件,对比分析了4种不同配筋形式低剪力墙的非线性性能,并对新型低剪力墙竖缝的开设位置进行了研究.试验结果与有限元分析表明：设置钢筋暗支撑、开缝及设置钢板的方式均可改善传统低剪力墙的延性及变形性能;与带暗支撑低剪力墙相比,新型低剪力墙的变形能力及耗能能力提高显著,抗震性能更好,且具有明显的多道抗震防线. 相似文献
18.
The histochemical reaction for phosphorylase is completely lost from anterior horn neurons rich in phosphorylase within 72 hours after proximal or distal axonal section. Using this new type of axonal reaction as a marking technique in the anterior horn of the seventh lumbar spinal cord segment of the cat, we demonstrated that (i) alpha motor neurons of slow twitch motor units, like those of fast twitch motor units, are rich in phosphorylase and poor in succinate dehydrogenase, and (ii) interneurons and Renshaw neurons are rich in succinate dehydrogenase and poor in phosphorylase. Gamma motor neurons, because of their small size, are considered to be rich in succinate dehydrogenase and poor in phosphorylase. Thus, anterior horn neurons capable of higher firing frequencies (Renshaw neurons, interneurons, and gamma motor neurons) are richer in mitochondrial oxidative enzyme activity as marked by succinate dehydrogenase. Those firing at lower frequencies (both types of alpha motor neurons) are richer in phosphorylase activity and glycogen content and, thus, apparently better equipped for anaerobic glycolysis. 相似文献
19.
针对王官溪蜜柚果实粒化、裂瓣与矿质营养的关系,对不同海拔高度果园的果实汁胞、叶片、土壤元素含量进行追踪分析．结果表明,果实粒化汁胞矿质成分（尤其是Ｎ、Ｐ、Ｋ）明显增加,裂瓣汁胞矿质成分亦呈增加趋势．叶片Ｎ、Ｋ、Ｂ、Ｚｎ含量高,Ｃａ含量低明显加剧果实粒化程度．果实裂瓣程度随叶片Ｂ含量增加而减轻．结果还表明,随土壤有效Ｃｕ含量增加,果实粒化程度加重,裂瓣程度减轻． 相似文献
20.
Identification of an intracellular peptide segment involved in sodium channel inactivation 总被引：25，自引：0，他引：25
Antibodies directed against a conserved intracellular segment of the sodium channel alpha subunit slow the inactivation of sodium channels in rat muscle cells. Of four site-directed antibodies tested, only antibodies against the short intracellular segment between homologous transmembrane domains III and IV slowed inactivation, and their effects were blocked by the corresponding peptide antigen. No effects on the voltage dependence of sodium channel activation or of steady-state inactivation were observed, but the rate of onset of the antibody effect and the extent of slowing of inactivation were voltage-dependent. Antibody binding was more rapid at negative potentials, at which sodium channels are not inactivated; antibody-induced slowing of inactivation was greater during depolarizations to more positive membrane potentials. The peptide segment recognized by this antibody appears to participate directly in rapid sodium channel inactivation during large depolarizations and to undergo a conformational change that reduces its accessibility to antibodies as the channel inactivates. 相似文献