A model for the joint evaluation of burstiness and regularity in oscillatory spike trains

Poster presentation: Introduction The ability of neurons to emit different firing patterns is considered relevant for neuronal information processing. In dopaminergic neurons, prominent patterns include highly regular pacemakers with separate spikes and stereotyped intervals, processes with repetitive bursts and partial regularity, and irregular spike trains with nonstationary properties. In order to model and quantify these processes and the variability of their patterns with respect to pharmacological and cellular properties, we aim to describe the two dimensions of burstiness and regularity in a single model framework. Methods We present a stochastic spike train model in which the degree of burstiness and the regularity of the oscillation are described independently and with two simple parameters. In this model, a background oscillation with independent and normally distributed intervals gives rise to Poissonian spike packets with a Gaussian firing intensity. The variability of inter-burst intervals and the average number of spikes in each burst indicate regularity and burstiness, respectively. These parameters can be estimated by fitting the model to the autocorrelograms. This allows to assign every spike train a position in the two-dimensional space described by regularity and burstiness and thus, to investigate the dependence of the firing patterns on different experimental conditions. Finally, burst detection in single spike trains is possible within the model because the parameter estimates determine the appropriate bandwidth that should be used for burst identification. Results and Discussion We applied the model to a sample data set obtained from dopaminergic substantia nigra and ventral tegmental area neurons recorded extracellularly in vivo and studied differences between the firing activity of dopaminergic neurons in wildtype and K-ATP channel knock-out mice. The model is able to represent a variety of discharge patterns and to describe changes induced pharmacologically. It provides a simple and objective classification scheme for the observed spike trains into pacemaker, irregular and bursty processes. In addition to the simple classification, changes in the parameters can be studied quantitatively, also including the properties related to bursting behavior. Interestingly, the proposed algorithm for burst detection may be applicable also to spike trains with nonstationary firing rates if the remaining parameters are unaffected. Thus, the proposed model and its burst detection algorithm can be useful for the description and investigation of neuronal firing patterns and their variability with cellular and experimental conditions

The Noise of Multilingualism: Reader Diversity, Linguistic Borders and Literary Multimodality

The article proposes a new multimodal approach to literary multilingualism, with special attention devoted to how readers with different language skills partake in making literary multilingualism happen. It presents a critical assessment of previous scholarship on literary multilingualism, which we claim is characterized by monolingual assumptions and a problematic division between mono- and multilingual literature. As a continuation of the theoretical argument, multimodal readings of three contemporary poets Cia Rinne, Caroline Bergvall and Ralf Andtbacka are presented. Instances of contemporary multilingual poetry, the article concludes, can help us to critically scrutinize notions of clear-cut linguistic borders, as well as to study the intricate dynamics between the acoustic and visual aspects of literary multilingualism

The Reader as Multilingual Soloist: Linguistic and Medial Transgressions in the Poetry of Cia Rinne

Der vorliegende Beitrag untersucht den Lyrikband notes for soloists (2009) der transnationalen Lyrikerin Cia Rinne mit einem besonderen Schwerpunkt auf der Frage der literarischen Vielsprachigkeit und der Intermedialität des Textes. Mit Ausgangspunkt in Naoki Sakais Verständnis von Übersetzung als bordering (Sakai 2009) wird die Rolle des Lesers von notes for soloists als Erzeuger sprachlicher Grenzen hervorgehoben. Hierbei funktioniert Rinnes mehrsprachiger und intermedialer Text als eine Art Partitur, die Leser verschiedener Sprachkompetenz auf unterschiedliche Weise realisieren. Es wird veranschaulicht, wie die Dynamik zwischen dem gedruckten Text und den verschiedenen artikulatorischen Möglichkeiten des Textes die Leser in eine Sphäre zwischen Sonorität und sprachlicher Artikulation versetzt; eine Sphäre, die normalerweise kleinen Kindern, die noch keine Sprache beherrschen, vorbehalten ist. Dabei wird die Kontingenz sprachlicher Grenzen ins Auge gefasst, zugleich werden jedoch auch mögliche Verbindungen zwischen verschiedenen für die Leser unbekannten bzw. bekannten Sprachen vorgeführt

Compression-Responsive Photonic Crystals Based on Fluorine-Containing Polymers

Fluoropolymers represent a unique class of functional polymers due to their various interesting and important properties such as thermal stability, resistance toward chemicals, repellent behaviors, and their low refractive indices in comparison to other polymeric materials. Based on the latter optical property, fluoropolymers are particularly of interest for the preparation of photonic crystals for optical sensing application. Within the present study, photonic crystals were prepared based on core-interlayer-shell particles focusing on fluoropolymers. For particle assembly, the melt-shear organization technique was applied. The high order and refractive index contrast of the individual components of the colloidal crystal structure lead to remarkable reflection colors according to Bragg’s law of diffraction. Due to the special architecture of the particles, consisting of a soft core, a comparably hard interlayer, and again a soft shell, the resulting opal films were capable of changing their shape and domain sizes upon applied pressure, which was accompanied with a (reversible) change of the observed reflection colors as well. By the incorporation of adjustable amounts of UV cross-linking agents into the opal film and subsequent treatment with different UV irradiation times, stable and pressure-sensitive opal films were obtained. It is shown that the present strategy led to (i) pressure-sensitive opal films featuring reversibly switchable reflection colors and (ii) that opal films can be prepared, for which the written pattern—resulting from the compressed particles—could be fixed upon subsequent irradiation with UV light. The herein described novel fluoropolymer-containing photonic crystals, with their pressure-tunable reflection color, are promising candidates in the field of sensing devices and as potential candidates for anti-counterfeiting materials

Illuminating Summary Evaluations –The Importance of an Attitude’s Structural Consistency in Explaining IS Usage

Although attitudes are frequently hypothesized to guide information system (IS) usage behavior, existent empirical evidence on their explanatory power is inconclusive. We thus suggest in this paper the consideration of an attitude\u27s strength that stems from its structural consistency. First, we illuminate the structure that underlies attitudes from a theoretical perspective and hypothesize that its consistency marks strong attitudes that explain IS usage. Second, we provide empirical evidence on structurally consistent attitudes explaining IS usage intention in the specific context of social network sites. By focusing on attitude, we investigate in this paper a less-studied side of existent IS adoption theories and show the merits of considering an attitude\u27s strength as indicated by its structural consistency in explaining IS usage

Diattenuation of Brain Tissue and its Impact on 3D Polarized Light Imaging

3D-Polarized Light Imaging (3D-PLI) reconstructs nerve fibers in histological brain sections by measuring their birefringence. This study investigates another effect caused by the optical anisotropy of brain tissue - diattenuation. Based on numerical and experimental studies and a complete analytical description of the optical system, the diattenuation was determined to be below 4 % in rat brain tissue. It was demonstrated that the diattenuation effect has negligible impact on the fiber orientations derived by 3D-PLI. The diattenuation signal, however, was found to highlight different anatomical structures that cannot be distinguished with current imaging techniques, which makes Diattenuation Imaging a promising extension to 3D-PLI.Comment: 32 pages, 15 figure

Structure elucidation of polyheptazine imide by electron diffraction — a templated 2D carbon nitride networkw

Structure elucidation of a condensed carbon IV) nitride with a stoichiometry close to C3N4 by electron diffraction reveals a two-dimensional planar heptazine-based network containing isolated melamine molecules in the trigonal voids

A Jones matrix formalism for simulating three-dimensional polarized light imaging of brain tissue

The neuroimaging technique three-dimensional polarized light imaging (3D-PLI) provides a high-resolution reconstruction of nerve fibres in human post-mortem brains. The orientations of the fibres are derived from birefringence measurements of histological brain sections assuming that the nerve fibres - consisting of an axon and a surrounding myelin sheath - are uniaxial birefringent and that the measured optic axis is oriented in direction of the nerve fibres (macroscopic model). Although experimental studies support this assumption, the molecular structure of the myelin sheath suggests that the birefringence of a nerve fibre can be described more precisely by multiple optic axes oriented radially around the fibre axis (microscopic model). In this paper, we compare the use of the macroscopic and the microscopic model for simulating 3D-PLI by means of the Jones matrix formalism. The simulations show that the macroscopic model ensures a reliable estimation of the fibre orientations as long as the polarimeter does not resolve structures smaller than the diameter of single fibres. In the case of fibre bundles, polarimeters with even higher resolutions can be used without losing reliability. When taking the myelin density into account, the derived fibre orientations are considerably improved.Comment: 20 pages, 8 figure

Correction: Meta-Analysis of the Relationship between Multiple Sclerosis and Migraine.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.PMCID: PMC3613438PMCID: PMC3613438PMCID: PMC3613438PMCID: PMC3613438[This corrects the article on p. e45295 in vol. 7.]