Specific Intrinsic Properties Research Articles

Electrophysiological Recordings from Identified Cell Types in the Olfactory Cortex of Awake Mice.

Neural circuits consist of a myriad of distinct cell types, each with specific intrinsic properties and patterns of synaptic connectivity, which transform neural input and convey this information to downstream targets. Understanding how different features of an odor stimulus are encoded and relayed to their appropriate targets will require selective identification and manipulation of these different elements of the circuit. Here, we describe methods to obtain dense, extracellular electrophysiological recordings of odor-evoked activity in olfactory (piriform) cortex of awake, head-fixed mice, and optogenetic tools and procedures to identify genetically defined cell types within this circuit.

The murine male reproductive organ at a glance: Three-dimensional insights and virtual histology using label-free light sheet microcopy.

The unique anatomy of the male reproductive organ reflects its complex function from sperm maturation to their storage for months until emission. Since light microscopy in two dimensions (2d) cannot sufficiently demonstrate its complex morphology, a comprehensive visualization is required to identify pathologic alterations in its entire anatomical context. Aim of this study was to use three-dimensional (3d) light sheet fluorescence microscopy (LSFM) to visualize entire murine testes in 3d, label-free and at subcellular resolution, and to assign local autofluorescence to testicular and deferent structures. Murine testes were fixed with four different fixatives and subsequently cleared with benzoic acid/benzyl benzoate. Hereafter, complete murine testes were scanned with LSFM with different fluorescence filter sets and subsequently embedded in paraffin for further conventional planar histology. Autofluorescence signals of the murine reproductive organ allowed the unambiguous identification of the testicular anatomy from the seminiferous tubules to the vas deferens with their specific stratification independent of the used fixative. Blood vessels were visualized from the pampiniform plexus to the small capillaries of single tubules. Moreover, due to the specific intrinsic fluorescence properties of the efferent ducts and the epididymis, luminal caliber, the epithelial stratification and retronuclear cytoplasmic inclusions gave a unique insight into the interface of both morphological structures. Subsequent 2d histology confirmed the identified morphological structures. LSFM analysis of the murine reproductive organ allows due to its intrinsic fluorescence a simple, label-free 3d assessment of its entire duct morphology, the epithelial composition, and the associated blood supply in its anatomical relation. LSFM provides the technical basis for comprehensive analyses of pathologically altered murine testes in its entirety by depicting specific autofluorescence. Thereby it facilitates mouse studies of testicular disease or their drug-related alterations in more detail potentially for clinical translation assessing human testicular biopsies.

An overview of microglia ontogeny and maturation in the homeostatic and pathological brain.

Microglia are the resident immune cells of the central nervous system (CNS) and are increasingly recognized as critical players in development, brain homeostasis, and disease pathogenesis. The lifespan, maintenance, proliferation, and turnover of microglia are important factors that regulate microglial behavior and affect their roles in the CNS. However, emerging evidence suggests that microglia are morphologically and phenotypically distinct in different brain areas, at different ages, and during disease. Ongoing research focuses on understanding how microglia acquire specific phenotypes in response to extrinsic cues in the environment and how phenotypes are specified by intrinsic properties of different populations of microglia. With the development of pharmacological and genetic tools that allow the investigation of microglia in vivo, there have been considerable advances in understanding molecular signatures of both homeostatic microglia and those reacting to injury and disease. Here, we review the master gene regulators that define microglia as well as discuss the evidence that microglia are heterogeneous and fall into distinct clusters that display specific intrinsic properties and perform unique tasks in different settings. Taken together, the information presented supports the idea that microglia morphology and transcriptional heterogeneity should be considered when studying the complex nature of microglia and their roles in brain health and disease.

Simulated auditory fiber myelination heterogeneity desynchronizes population responses to electrical stimulation limiting inter-aural timing difference representation.

Auditory nerve responses to electrical stimulation exhibit aberrantly synchronous response latencies to low-rate pulse trains, nevertheless, cochlear implant users generally have elevated inter-aural timing difference detection thresholds. These findings present an apparent paradox in which single units are unusually precise but downstream within the auditory pathway access to this precision is lost. Auditory nerves innervating a region of cochlea exhibit natural heterogeneity in their diameter, myelination, and other structural properties; a key question is whether this diversity may contribute to the loss of temporal fidelity. In this work, responses of simulated auditory neuron populations with realistic intrinsic diameter and myelination heterogeneity to low-rate pulse trains were produced. By performing a receiver operating characteristic analysis on response latency distributions, ideal-observer interaural timing difference (ITD) detection limits were produced for each population. Fiber heterogeneity produced dispersion of inter-fiber latencies that produced ITD thresholds like that observed in the best performing cochlear implant users. Incorporation of myelin loss into these populations further increased inter-fiber latency variance and elevated ITD detection limits. These findings suggest that the interaction of applied currents with fibers' specific intrinsic properties may introduce fundamental limits on presentation of fine temporal structure in electrical stimulation.

Interneuron Functional Diversity in the Mouse Accessory Olfactory Bulb.

In the mouse accessory olfactory bulb (AOB), inhibitory interneurons play an essential role in gating behaviors elicited by sensory exposure to social odors. Several morphological classes have been described, but the full complement of interneurons remains incomplete. In order to develop a more comprehensive view of interneuron function in the AOB, we performed targeted patch clamp recordings from partially overlapping subsets of genetically labeled and morphologically defined interneuron types. Gad2 (GAD65), Calb2 (calretinin), and Cort (cortistatin)-cre mouse lines were used to drive selective expression of tdTomato in AOB interneurons. Gad2 and Calb2-labeled interneurons were found in the internal, external, and glomerular (GL) layers, whereas Cort-labeled interneurons were enriched within the lateral olfactory tract (LOT) and external cellular layer (ECL). We found that external granule cells (EGCs) from all genetically labeled subpopulations possessed intrinsic functional differences that allowed them to be readily distinguished from internal granule cells (IGCs). EGCs showed stronger voltage-gated Na+ and non-inactivating voltage-gated K+ currents, decreased IH currents, and robust excitatory synaptic input. These specific intrinsic properties did not correspond to any genetically labeled type, suggesting that transcriptional heterogeneity among EGCs and IGCs is not correlated with expression of these particular marker genes. Intrinsic heterogeneity was also seen among AOB juxtaglomerular cells (JGCs), with a major subset of Calb2-labeled JGCs exhibiting spontaneous and depolarization-evoked plateau potentials. These data identify specific physiological features of AOB interneurons types that will assist in future studies of AOB function.

Magneto-optical and thermal characteristics of magnetite nanoparticle-embedded DNA and CTMA-DNA thin films

Recently, DNA molecules embedded with magnetite (Fe3O4) nanoparticles (MNPs) drew much attention for their wide range of potential usage. With specific intrinsic properties such as low optical loss, high transparency, large band gap, high dielectric constant, potential for molecular recognition, and their biodegradable nature, the DNA molecule can serve as an effective template or scaffold for various functionalized nanomaterials. With the aid of cetyltrimethylammonium (CTMA) surfactant, DNA can be used in organic-based applications as well as water-based ones. Here, DNA and CTMA-DNA thin films with various concentrations of MNPs fabricated by the drop-casting method have been characterized by optical absorption, refractive index, Raman, and cathodoluminescence measurements to understand the binding, dispersion, chemical identification/functional modes, and energy transfer mechanisms, respectively. In addition, magnetization was measured as a function of either applied magnetic field or temperature in field cooling and zero field cooling. Saturation magnetization and blocking temperature demonstrate the importance of MNPs in DNA and CTMA-DNA thin films. Finally, we examine the thermal stabilities of MNP-embedded DNA and CTMA-DNA thin films through thermogravimetric analysis, derivative thermogravimetry, and differential thermal analysis. The unique optical, magnetic, and thermal characteristics of MNP-embedded DNA and CTMA-DNA thin films will prove important to fields such as spintronics, biomedicine, and function-embedded sensors and devices.

High-temperature thermodynamic properties of nanocrystalline CdSe thin film

ABSTRACTThe thermodynamic properties of the nanocrystalline CdSe (nc-CdSe) thin film were studied by in situ high-temperature X-ray diffraction measurement over the temperature range 288–1073 K. It is shown that nc-CdSe thin film has high thermal stability and no phase transformation up to 1002 K. Lattice parameter, thermal expansion coefficients along c-axis and crystal quality increased with the increase of temperature, but dislocation density and strain decreased with the increase of temperature. Surface effect and size effect are two of the most specific intrinsic properties of nc-CdSe thin films, both of which are of great significance to the thermodynamic properties. This work has provided a reliable basis for the research of nc-CdSe devices at high temperature.

Dynamical and Reversible Control of Topological Spin Textures.

Recent observations of topological spin textures brought spintronics one step closer to new magnetic memories. Nevertheless, the existence of Skyrmions, as well as their stabilization, require very specific intrinsic magnetic properties which are usually fixed in magnets. Here we address the possibility to dynamically control their intrinsic magnetic interactions by varying the strength of a high-frequency laser field. It is shown that drastic changes can be induced in the antiferromagnetic exchange interactions and the latter can even be reversed to become ferromagnetic, provided the direct exchange is already non-negligible in equilibrium as predicted, for example, in Si doped with C, Sn, or Pb adatoms. In the presence of Dzyaloshinskii-Moriya interactions, this enables us to tune features of ferromagnetic Skyrmions such as their radius, making them easier to stabilize. Alternatively, such topological spin textures can occur in frustrated triangular lattices. Then, we demonstrate that a high-frequency laser field can induce dynamical frustration in antiferromagnets, where the degree of frustration can subsequently be tuned suitably to drive the material toward a Skyrmionic phase.

Design for Change and Circularity – Accommodating Circular Material & Product Flows in Construction

Circular building concepts, as proposed within e.g. Circular Economy and Cradle-to-Cradle frameworks, imply radical changes for the construction sector. Cradle-to-Cradle® in particular has put forward the idea of buildings as material banks, radically altering the way material flows need to be managed. The notion of material banks (temporary storage of materials that comprise the building assemblies) sheds new light on the value of building materials and products, and how to maintain and restore this. The basics are straightforward: high quality, pure material use and anticipated material regeneration routes. The implications for the supply and value chain, however, are significant, and research in this direction has only recently taken off. To smoothen the path to implementation, circular building principles may be combined with Design-for-Adaptability (DfA) guidelines, as developed over the last decades. DfA guidelines are rooted in enhanced resilience of the built environment on the one hand, and the associated constructive implications on the other. Synergy between the concepts of circularity and adaptability, with regard to the Dutch context, is at the heart of this paper. The main research question is: what are prerequisites for an effective performance of materials, products, services and buildings in the case circularity is a leading ambition? The research is structured around four interdisciplinary expert workshops in which knowledge and experiences were shared, discussed, tested and redefined, leading to a set of preconditions for circular building material and product flows. A key finding is that circularity-values emerge at the intersection of specific intrinsic properties (material and product characteristics) and relational properties (building design and use characteristics), whilst combining multiple parameters. In separation, neither intrinsic nor relational properties have decisive significance with regard to circularity; it is on the crossing where fulfillment is created. This paper finishes by discussing the findings from the perspectives of lifespan, monitoring, ownership, and standardization.

Topical antifungal-corticosteroid combination therapy for the treatment of superficial mycoses: conclusions of an expert panel meeting.

Superficial fungal infections affect 20-25% of people worldwide and can cause considerable morbidity, particularly if an inflammatory component is present. As superficial fungal infections can be diverse, the treatment should be tailored to the individual needs of the patient and several factors should be taken into account when deciding on the most appropriate treatment option. These include the type, location and surface area of the infection, patient age, degree of inflammation and underlying comorbidities. Although several meta-analyses have shown that there are no significant differences between the numerous available topical antifungal agents with regard to mycological cure, agents differ in their specific intrinsic properties, which can affect their clinical use. The addition of a corticosteroid to an antifungal agent at the initiation of treatment can attenuate the inflammatory symptoms of the infection and is thought to increase patient compliance, reduce the risk of bacterial superinfection and enhance the efficacy of the antifungal agent. However, incorrect use of antifungal-corticosteroid therapy may be associated with treatment failure and adverse effects. This review summarises available treatment options for superficial fungal infections and provides general treatment recommendations based on the consensus outcomes of an Expert Panel meeting on the topical treatment of superficial mycoses.

Optogenetic stimulation reveals distinct modulatory properties of thalamostriatal vs corticostriatal glutamatergic inputs to fast-spiking interneurons.

Parvalbumin-containing fast-spiking interneurons (FSIs) exert a powerful feed-forward GABAergic inhibition on striatal medium spiny neurons (MSNs), playing a critical role in timing striatal output. However, how glutamatergic inputs modulate their firing activity is still unexplored. Here, by means of a combined optogenetic and electrophysiological approach, we provide evidence for a differential modulation of cortico- vs thalamo-striatal synaptic inputs to FSIs in transgenic mice carrying light-gated ion channels channelrhodopsin-2 (ChR2) in glutamatergic fibers. Corticostriatal synapses show a postsynaptic facilitation, whereas thalamostriatal synapses present a postsynaptic depression. Moreover, thalamostriatal synapses exhibit more prominent AMPA-mediated currents than corticostriatal synapses, and an increased release probability. Furthermore, during current-evoked firing activity, simultaneous corticostriatal stimulation increases bursting activity. Conversely, thalamostriatal fiber activation shifts the canonical burst-pause activity to a more prolonged, regular firing pattern. However, this change in firing pattern was accompanied by a significant rise in the frequency of membrane potential oscillations. Notably, the responses to thalamic stimulation were fully abolished by blocking metabotropic glutamate 1 (mGlu1) receptor subtype, whereas both acetylcholine and dopamine receptor antagonists were ineffective. Our findings demonstrate that cortical and thalamic glutamatergic input differently modulate FSIs firing activity through specific intrinsic and synaptic properties, exerting a powerful influence on striatal outputs.

Calculations of the magnetic properties of R2M14B intermetallic compounds (R=rare earth, M=Fe, Co)

The hard magnetic properties of “R–M–B” (R=rare earth, M=mainly Fe) magnets derive from the specific intrinsic magnetic properties encountered in Fe-rich R2M14B compounds. Exchange interactions are dominated by the 3d elements, Fe and Co, and may be modeled at the macroscopic scale with good accuracy. Based on classical formulae that relate the anisotropy coefficients to the crystalline electric field parameters and exchange interactions, a simple numerical approach is used to derive the temperature dependence of anisotropy in various R2Fe14B compounds (R=Pr, Nd, Dy). Remarkably, a unique set of crystal field parameters give fair agreement with the experimentally measured properties of all compounds. This implies reciprocally that the properties of compounds that incorporate a mixture of different rare-earth elements may be predicted accurately. This is of special interest for material optimization that often involves the partial replacement of Nd with another R element and also the substitution of Co for Fe.

Nonlocal beam model for axial buckling of carbon nanotubes with surface effect

Small-size effect and surface effect are two of the most specific intrinsic properties of nanostructures, both of which are of great significance to the related applications. In this letter, the nonlocal Euler-Bernoulli beam model, together with surface elasticity and surface tension are implemented to investigate the buckling behavior of axially compressed carbon nanotubes. Explicit expression of solutions to the critical buckling loads corresponding to typical boundary conditions is presented. Through contrast to molecular dynamics results, it is vitally important to note that both small-size effect and surface effect have a profound consequence and should be taken into account thoroughly.

Viral Sequence Variation in Chronic Carriers of Hepatitis C Virus Has a Low Impact on Liver Steatosis

Most clinical studies suggest that the prevalence and severity of liver steatosis are higher in patients infected with hepatitis C virus (HCV) genotype 3 than in patients infected with other genotypes. This may reflect the diversity and specific intrinsic properties of genotype 3 virus proteins. We analyzed the possible association of particular residues of the HCV core and NS5A proteins known to dysregulate lipid metabolism with steatosis severity in the livers of patients chronically infected with HCV. We used transmission electron microscopy to quantify liver steatosis precisely in a group of 27 patients, 12 of whom were infected with a genotype 3 virus, the other 15 being infected with viruses of other genotypes. We determined the area covered by lipid droplets in liver tissues and analyzed the diversity of the core and NS5A regions encoded by the viral variants circulating in these patients. The area covered by lipid droplets did not differ significantly between patients infected with genotype 3 viruses and those infected with other genotypes. The core and NS5A protein sequences of the viral variants circulating in patients with mild or severe steatosis were evenly distributed throughout the phylogenic trees established from all the collected sequences. Thus, individual host factors seem to play a much greater role than viral factors in the development of severe steatosis in patients chronically infected with HCV, including those infected with genotype 3 viruses.

An Analytical Model for Determining Two-Dimensional Receptor-Ligand Kinetics

Cell-cell adhesive interactions play a pivotal role in major pathophysiological vascular processes, such as inflammation, infection, thrombosis, and cancer metastasis, and are regulated by hemodynamic forces generated by blood flow. Cell adhesion is mediated by the binding of receptors to ligands, which are both anchored on two-dimensional (2-D) membranes of apposing cells. Biophysical assays have been developed to determine the unstressed (no-force) 2-D affinity but fail to disclose its dependence on force. Here we develop an analytical model to estimate the 2-D kinetics of diverse receptor-ligand pairs as a function of force, including antibody-antigen, vascular selectin-ligand, and bacterial adhesin-ligand interactions. The model can account for multiple bond interactions necessary to mediate adhesion and resist detachment amid high hemodynamic forces. Using this model, we provide a generalized biophysical interpretation of the counterintuitive force-induced stabilization of cell rolling observed by a select subset of receptor-ligand pairs with specific intrinsic kinetic properties. This study enables us to understand how single-molecule and multibond biophysics modulate the macroscopic cell behavior in diverse pathophysiological processes.

Cholesteric liquid crystal self-organization of gold nanoparticles

Self-organization processes are present in many different inorganic, organic, and biological systems at various length scales and give rise to specific intrinsic physical properties. In the present work, we demonstrate the symbiotic association of gold nanoparticles within a cholesteric (chiral) liquid crystal, and we report the long-range growth of two-dimensional and three-dimensional self-organized arrangements of gold nanoparticles into various cholesteric textures. The structure of these novel nanomaterials is imaged at various scales—from the macroscopic scale of centimetre-size cells to the nanoscale of self-assemblies—and we demonstrate that the nanoparticle pattern depends strongly on film thickness. Furthermore, we investigate how fundamental optical properties such as selective reflection are affected when cholesteric liquid crystals are doped with gold nanoparticles. Potential applications are envisioned in the field of soft nanotechnology and optical materials.

‘Leaky’ neurons in the epileptic hippocampus: should we get excited?

‘Leaky’ neurons in the epileptic hippocampus: should we get excited?

The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons

Event Abstract Back to Event The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons Rejean Dubuc1* 1 Universite du Quebec aMontreal, Departement de Kinanthropologie, Canada Sensory stimulation is known to elicit locomotion. The locomotor bouts allow for instance an animal to escape away from a stimulus. We have examined the neural networks and cellular properties that are involved in escape locomotor behaviour in lampreys. We showed that sensory stimulation elicits sustained depolarizations in reticulospinal cells, considered to be brainstem command neurons responsible for initiating locomotion. The sustained depolarizations are triggered by glutamate transmission and the activation of NMDA receptors in reticulospinal cells results in calcium entry, which in turn activates specific intrinsic properties that are crucial for maintaining the reticulospinal cells into a depolarized state. We provided evidence that a calcium activated nonselective cationic current (ICAN) is involved. Whether such a conductance can maintain the cells depolarized for a very long time, up to minutes as seen in locomotor behaviour, was questionable and we examined the possibility that synaptic inputs could cooperate with intrinsic properties to amplify the duration of sustained depolarizations. Ascending spinal inputs to reticulospinal cells were reversibly blocked by applying xylocaine over the rostral spinal cord segments. Under this condition, the duration of the sustained depolarizations was markedly reduced. The contribution of excitatory glutamatergic inputs was then assessed by applying CNQX and AP- 5 over one of two simultaneously recorded bilaterally homologous reticulospinal cells. The amplitude of sensory-evoked depolarization decreased significantly in the cell exposed to the antagonists compared to the contralateral control reticulospinal cell. In contrast, local application of glycine produced a transient membrane potential hyperpolarization, but did not end the sustained depolarization. Locally applied strychnine did not change the duration of the sustained depolarizations. Application of GABA did not abolish the sustained depolarizations and thus mechanisms other than glycinergic or GABAergic inhibition are needed to end the sustained depolarizations in reticulospinal cells. Taken together, our results suggest that ascending excitatory spinal inputs cooperate with intrinsic properties of reticulospinal cells to maintain the cells depolarized for a prolong time after sensory activation. Behaviourally, this would permit to sustain long bouts of escape swimming. Conference: 3rd Mediterranean Conference of Neuroscience , Alexandria, Egypt, 13 Dec - 16 Dec, 2009. Presentation Type: Oral Presentation Topic: Symposium 05 – Interactions of synaptic and intrinsic properties in rhythmic motor activities Citation: Dubuc R (2009). The co-operation of intrinsic and synaptic properties in brainstem locomotor command neurons. Front. Neurosci. Conference Abstract: 3rd Mediterranean Conference of Neuroscience . doi: 10.3389/conf.neuro.01.2009.16.032 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Nov 2009; Published Online: 19 Nov 2009. * Correspondence: Rejean Dubuc, Universite du Quebec aMontreal, Departement de Kinanthropologie, Beauport, Qc G1J 2G3, Canada, rejean.dubuc@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rejean Dubuc Google Rejean Dubuc Google Scholar Rejean Dubuc PubMed Rejean Dubuc Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Cell-type specific circuit analysis using a digital brain atlas which integrates anatomical and physiological data

Event Abstract Back to Event Cell-type specific circuit analysis using a digital brain atlas which integrates anatomical and physiological data Patrik Krieger1*, Bert Sakmann2, Alexander Groh2, Hanno Meyer2 and Nathaniel Heintz3 1 Karolinska Institutet, Sweden 2 Max Planck Institute for Medical Research, Germany 3 The Rockefeller University, United States In BAC (Bacterial artificial chromosome) transgenic mice we investigated the anatomical and functional properties of two populations of layer 5 pyramids in somatosensory and visual cortex. The two populations were selectively labelled by EGFP expressed under the control of cell-type specific promoters. The genotypic profile discriminated between thick-tufted corticopontine and slender-tufted corticostriatal layer 5 pyramids. The projection target specificity of the two populations was determined by retrograde tracer injections and visualization of EGFP-labelled axons in the target area. Using the fluorescent labelling we could target our investigation to a specific cell-type in layer 5 and perform (i) electrophysiological recordings to investigate cell-type specific intrinsic membrane properties and connectivity (ii) a quantification of the dendrite morphology and (iii) an analysis of the spatial distribution profiles of somata from the two populations and (iv) an investigation of the overlap of thalamocortical axons and dendrites from the two populations of corticofugal layer 5 pyramids. We show that targeting cell types using BAC-transgenic mice could be a valuable approach to generate atlases consisting of both detailed anatomical data, including both cell-type specific output and input, and physiological data relevant for functional circuit analysis. Conference: Neuroinformatics 2008, Stockholm, Sweden, 7 Sep - 9 Sep, 2008. Presentation Type: Poster Presentation Topic: General Neuroinformatics Citation: Krieger P, Sakmann B, Groh A, Meyer H and Heintz N (2008). Cell-type specific circuit analysis using a digital brain atlas which integrates anatomical and physiological data. Front. Neuroinform. Conference Abstract: Neuroinformatics 2008. doi: 10.3389/conf.neuro.11.2008.01.007 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 28 Jul 2008; Published Online: 28 Jul 2008. * Correspondence: Patrik Krieger, Karolinska Institutet, Stockholm, Sweden, patrik.krieger@rub.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Patrik Krieger Bert Sakmann Alexander Groh Hanno Meyer Nathaniel Heintz Google Patrik Krieger Bert Sakmann Alexander Groh Hanno Meyer Nathaniel Heintz Google Scholar Patrik Krieger Bert Sakmann Alexander Groh Hanno Meyer Nathaniel Heintz PubMed Patrik Krieger Bert Sakmann Alexander Groh Hanno Meyer Nathaniel Heintz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Continuous Tonic Spike Activity in Spider Warm Cells in the Absence of Sensory Input

The warm cells of the spider tarsal organ respond very sensitively to low-amplitude changes in temperature and discharge continuously as the rate of change in temperature reaches zero. To test whether the continuous tonic discharge remains without sensory input, we blocked the warm cell's receptive region by Epoxy glue. The activity continued in this situation, but its dependence on temperature changes was strongly reduced. We interpret this to mean that the warm cells exhibit specific intrinsic properties that underlie the generation of the tonic discharge. Experiments with electrical stimulation confirmed the observation that the warm cells persist in activity without an external drive. In warm cells with blocked receptive region, the response curves describing the relationship between the tonic discharge and the level of depolarization is the same for different temperatures. In warm cells with intact receptive region, the curves are shifted upward with rising temperature, as if the injected current is simply added to the receptor current. This indicates a modulating effect of the receptor current on the tonic discharge. Stimulation causes a change in the tonic discharge rate and thereby enables individual warm cells to signal the direction in addition to the magnitude of temperature changes.