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1.
In the brain, fast oscillations of local field potentials, which are thought to arise from the coherent and rhythmic activity of large numbers of neurons, were observed first in the olfactory system and have since been described in many neocortical areas. The importance of these oscillations in information coding, however, is controversial. Here, local field potential and intracellular recordings were obtained from the antennal lobe and mushroom body of the locust Schistocerca americana. Different odors evoked coherent oscillations in different, but usually overlapping, ensembles of neurons. The phase of firing of individual neurons relative to the population was not dependent on the odor. The components of a coherently oscillating ensemble of neurons changed over the duration of a single exposure to an odor. It is thus proposed that odors are encoded by specific but dynamic assemblies of coherently oscillating neurons. Such distributed and temporal representation of complex sensory signals may facilitate combinatorial coding and associative learning in these, and possibly other, sensory networks. 相似文献
2.
Ray RS Corcoran AE Brust RD Kim JC Richerson GB Nattie E Dymecki SM 《Science (New York, N.Y.)》2011,333(6042):637-642
Physiological homeostasis is essential for organism survival. Highly responsive neuronal networks are involved, but their constituent neurons are just beginning to be resolved. To query brain serotonergic neurons in homeostasis, we used a neuronal silencing tool, mouse RC::FPDi (based on the synthetic G protein-coupled receptor Di), designed for cell type-specific, ligand-inducible, and reversible suppression of action potential firing. In mice harboring Di-expressing serotonergic neurons, administration of the ligand clozapine-N-oxide (CNO) by systemic injection attenuated the chemoreflex that normally increases respiration in response to tissue carbon dioxide (CO(2)) elevation and acidosis. At the cellular level, CNO suppressed firing rate increases evoked by CO(2) acidosis. Body thermoregulation at room temperature was also disrupted after CNO triggering of Di; core temperatures plummeted, then recovered. This work establishes that serotonergic neurons regulate life-sustaining respiratory and thermoregulatory networks, and demonstrates a noninvasive tool for mapping neuron function. 相似文献
3.
Rhythmic activity in the neocortex varies with different behavioral and pathological states and in some cases may encode sensory information. However, the neural mechanisms of these oscillations are largely unknown. Many pyramidal neurons in layer 5 of the neocortex showed prolonged, 5- to 12-hertz rhythmic firing patterns at threshold. Rhythmic firing was due to intrinsic membrane properties, sodium conductances were essential for rhythmicity, and calcium-dependent conductances strongly modified rhythmicity. Isolated slices of neocortex generated epochs of 4- to 10-hertz synchronized activity when N-methyl-D-aspartate receptor-mediated channels were facilitated. Layer 5 was both necessary and sufficient to produce these synchronized oscillations. Thus, synaptic networks of intrinsically rhythmic neurons in layer 5 may generate or promote certain synchronized oscillations of the neocortex. 相似文献
4.
Identification of presynaptic neurons by laser photostimulation 总被引：1，自引：0，他引：1
An optical method involving the use of a laser and a novel fluorescent dye as a photostimulation probe has been developed to identify presynaptic neurons in a large ensemble of cells. Illumination of an extracellularly stained neuron by the laser microbeam evokes action potentials. With this technique an interneuron connecting identified leech neurons was quickly located. The method speeds up the elucidation of neuronal networks, especially when small cells are involved. 相似文献
5.
Thyrotropin-releasing hormone induces rhythmic bursting in neurons of the nucleus tractus solitarius 总被引：4，自引：0，他引：4
The nucleus tractus solitarius (NTS) contains neurons that are part of the central neuronal network controlling rhythmic breathing movements in mammals. Nerve terminals within the NTS show immunoreactivity to thyrotropin-releasing hormone (TRH), a neuropeptide that has potent stimulatory effects on respiration. By means of a brainstem slice preparation in vitro, TRH induced rhythmic bursting in neurons in the respiratory division of the NTS. The frequency of bursting was voltage-dependent and could be reset by short depolarizing current pulses. In the presence of tetrodotoxin, TRH produced rhythmic oscillations in membrane potential whose frequency was also voltage-dependent. These observations suggest that TRH modulates the membrane excitability of NTS neurons and allows them to express endogenous bursting activity. 相似文献
6.
The intrinsic electrophysiological properties of mammalian neurons: insights into central nervous system function 总被引：68，自引：0，他引：68
R R Llinás 《Science (New York, N.Y.)》1988,242(4886):1654-1664
This article reviews the electroresponsive properties of single neurons in the mammalian central nervous system (CNS). In some of these cells the ionic conductances responsible for their excitability also endow them with autorhythmic electrical oscillatory properties. Chemical or electrical synaptic contacts between these neurons often result in network oscillations. In such networks, autorhythmic neurons may act as true oscillators (as pacemakers) or as resonators (responding preferentially to certain firing frequencies). Oscillations and resonance in the CNS are proposed to have diverse functional roles, such as (i) determining global functional states (for example, sleep-wakefulness or attention), (ii) timing in motor coordination, and (iii) specifying connectivity during development. Also, oscillation, especially in the thalamo-cortical circuits, may be related to certain neurological and psychiatric disorders. This review proposes that the autorhythmic electrical properties of central neurons and their connectivity form the basis for an intrinsic functional coordinate system that provides internal context to sensory input. 相似文献
7.
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
8.
Whereas gamma-band neuronal oscillations clearly appear integral to visual attention, the role of lower-frequency oscillations is still being debated. Mounting evidence indicates that a key functional property of these oscillations is the rhythmic shifting of excitability in local neuronal ensembles. Here, we show that when attended stimuli are in a rhythmic stream, delta-band oscillations in the primary visual cortex entrain to the rhythm of the stream, resulting in increased response gain for task-relevant events and decreased reaction times. Because of hierarchical cross-frequency coupling, delta phase also determines momentary power in higher-frequency activity. These instrumental functions of low-frequency oscillations support a conceptual framework that integrates numerous earlier findings. 相似文献
9.
Minlebaev M Colonnese M Tsintsadze T Sirota A Khazipov R 《Science (New York, N.Y.)》2011,334(6053):226-229
During development, formation of topographic maps in sensory cortex requires precise temporal binding in thalamocortical networks. However, the physiological substrate for such synchronization is unknown. We report that early gamma oscillations (EGOs) enable precise spatiotemporal thalamocortical synchronization in the neonatal rat whisker sensory system. Driven by a thalamic gamma oscillator and initially independent of cortical inhibition, EGOs synchronize neurons in a single thalamic barreloid and corresponding cortical barrel and support plasticity at developing thalamocortical synapses. We propose that the multiple replay of sensory input in thalamocortical circuits during EGOs allows thalamic and cortical neurons to be organized into vertical topographic functional units before the development of horizontal binding in adult brain. 相似文献
10.
Szabadics J Varga C Molnár G Oláh S Barzó P Tamás G 《Science (New York, N.Y.)》2006,311(5758):233-235
Axons in the cerebral cortex receive synaptic input at the axon initial segment almost exclusively from gamma-aminobutyric acid-releasing (GABAergic) axo-axonic cells (AACs). The axon has the lowest threshold for action potential generation in neurons; thus, AACs are considered to be strategically placed inhibitory neurons controlling neuronal output. However, we found that AACs can depolarize pyramidal cells and can initiate stereotyped series of synaptic events in rat and human cortical networks because of a depolarized reversal potential for axonal relative to perisomatic GABAergic inputs. Excitation and signal propagation initiated by AACs is supported by the absence of the potassium chloride cotransporter 2 in the axon. 相似文献
11.
Neurons with oscillatory properties are a common feature of the nervous system, but little is known about how neural oscillators shape the behavior of neuronal networks or how network interactions influence the properties of neural oscillators. Mathematical models are used to examine the effect of electrically coupling an oscillatory neuron to a second neuron that is either silent or tonically firing. Models of oscillatory neurons with varying degrees of complexity show that this coupling can either increase or decrease the frequency of an oscillator, depending on its membrane potential wave form, the state of the neuron to which it is coupled, and the strength of the coupling. Thus, electrical coupling provides a flexible mechanism for modifying the behavior of an oscillatory neural network. 相似文献
12.
Communication between neurons in the brain occurs primarily through synapses made onto elaborate treelike structures called dendrites. New electrical and optical recording techniques have led to tremendous advances in our understanding of how dendrites contribute to neuronal computation in the mammalian brain. The varied morphology and electrical and chemical properties of dendrites enable a spectrum of local and long-range signaling, defining the input-output relationship of neurons and the rules for induction of synaptic plasticity. In this way, diversity in dendritic signaling allows individual neurons to carry out specialized functions within their respective networks. 相似文献
13.
Mapping neuronal inputs to REM sleep induction sites with carbachol-fluorescent microspheres 总被引：4，自引：0，他引：4
J J Quattrochi A N Mamelak R D Madison J D Macklis J A Hobson 《Science (New York, N.Y.)》1989,245(4921):984-986
The cholinergic agonist carbachol was conjugated to latex microspheres that were fluorescently labeled with rhodamine and used as neuroanatomical probes that show little diffusion from their injection site and retrogradely label neurons projecting to the injection site. Microinjection of this pharmacologically active probe into the gigantocellular field of the cat pontine brain stem caused the awake cats to fall into rapid movement (REM) sleep indistinguishable from that produced by free carbachol. Three-dimensional computer reconstruction of the retrogradely labeled neurons revealed a widely distributed neuronal network in the pontine tegmentum. These pharmacologically active microspheres permit a new precision in the characterization and mapping of neurons associated with the control of behavioral state and of other cholinergic networks. 相似文献
14.
Circadian rhythm of redox state regulates excitability in suprachiasmatic nucleus neurons 总被引：1，自引：0，他引：1
TA Wang YV Yu G Govindaiah X Ye L Artinian TP Coleman JV Sweedler CL Cox MU Gillette 《Science (New York, N.Y.)》2012,337(6096):839-842
15.
Two-way communication between neurons and nonneural cells called glia is essential for axonal conduction, synaptic transmission, and information processing and thus is required for normal functioning of the nervous system during development and throughout adult life. The signals between neurons and glia include ion fluxes, neurotransmitters, cell adhesion molecules, and specialized signaling molecules released from synaptic and nonsynaptic regions of the neuron. In contrast to the serial flow of information along chains of neurons, glia communicate with other glial cells through intracellular waves of calcium and via intercellular diffusion of chemical messengers. By releasing neurotransmitters and other extracellular signaling molecules, glia can affect neuronal excitability and synaptic transmission and perhaps coordinate activity across networks of neurons. 相似文献
16.
随着人工智能的高速发展,越来越多的神经元模型相继被提出,现有的神经元电路主要由普通晶体管、运算放大器等高功耗器件构成,存在结构复杂、集成度不高、兼容性差、功耗高、阈值调节难度高的缺点.针对以上不足,首次提出了一种全新的神经元结构,该结构仅由神经元晶体管、忆阻器和普通电阻构成,相比传统神经元电路,不包含复杂的差分运算电路以及电流与电压信号的转换电路,电路结构简单,同时具有良好的电路兼容性,可用于大规模集成.该结构利用神经元晶体管的加权求和特性以及阈值可控功能来模拟神经元信息传导过程,同时利用阈值忆阻器的阈值特性和阻值连续变化能力来设定和更新突触权值,使得该新型神经元结构不仅能实现传统神经元电路功能的同时,还具有能耗低、阈值动态可控、权值可编程的优点,不仅极大地简化了网络结构,还能加强网络性能.其次,还提出了基于这种新型神经元结构的忆阻离散Hopfield神经网络,该忆阻神经网络有助于促进人工神经形态系统的硬件实现,使神经网络系统能耗降低,集成度极大地提高,将这种网络运用在联想记忆和彩色数字图像恢复中,进一步说明了基于全新神经元结构的忆阻离散hopfield神经网络的实用性以及有效性. 相似文献
17.
18.
Electrical activity in neurons is generally initiated in dendritic processes then propagated along axons to synapses, where it is passed to other neurons. Major structural features of neurons-their dendrites and axons-are thus related to their fundamental functions: the receipt and transmission of information. The acquisition of these distinct properties by dendrites and axons, called polarization, is a critical step in neuronal differentiation. We show here that SAD-A and SAD-B, mammalian orthologs of a kinase needed for presynaptic differentiation in Caenorhabditis elegans, are required for neuronal polarization. These kinases will provide entry points for unraveling signaling mechanisms that polarize neurons. 相似文献
19.
为明确不同培养方法对新生大鼠大脑皮质神经元成熟时间、形态特征、纯度及活力等生物学特性的影响,采用DMEM培养基加Neurobasal无血清培养基法或Neurobasal无血清培养基法原代培养新生24h内SD大鼠大脑皮质神经元,倒置显微镜下观察细胞形态,MTT法检测细胞活力,免疫荧光细胞化学染色法检测神经元纯度及活性.结果显示,2种方法培养的神经元形态差异无统计学意义;但与DMEM培养基加Neurobasal无血清培养基法相比,Neurobasal无血清培养基法培养的神经元成熟更早,数目更多,纯度更高,活力更强(p0.05).结果提示,原代培养的大脑皮质神经元部分生物学特性受培养方法直接影响;Neurobasal无血清培养基法所得神经元纯度与活性较高,这为实验目的导向的神经元原代培养方法选择提供了借鉴. 相似文献
20.
Leinekugel X Khazipov R Cannon R Hirase H Ben-Ari Y Buzsáki G 《Science (New York, N.Y.)》2002,296(5575):2049-2052
The behavior of immature cortical networks in vivo remains largely unknown. Using multisite extracellular and patch-clamp recordings, we observed recurrent bursts of synchronized neuronal activity lasting 0.5 to 3 seconds that occurred spontaneously in the hippocampus of freely moving and anesthetized rat pups. The influence of slow rhythms (0.33 and 0.1 hertz) and the contribution of both gamma-aminobutyric acid A-mediated and glutamate receptor-mediated synaptic signals in the generation of hippocampal bursts was reminiscent of giant depolarizing potentials observed in vitro. This earliest pattern, which diversifies during the second postnatal week, could provide correlated activity for immature neurons and may underlie activity-dependent maturation of the hippocampal network. 相似文献