Predictive Power of a Bayesian Effective Action for Fully Connected One Hidden Layer Neural Networks in the Proportional Limit.

We perform accurate numerical experiments with fully connected one hidden layer neural networks trained with a discretized Langevin dynamics on the MNIST and CIFAR10 datasets. Our goal is to empirically determine the regimes of validity of a recently derived Bayesian effective action for shallow architectures in the proportional limit. We explore the predictive power of the theory as a function of the parameters (the temperature T, the magnitude of the Gaussian priors λ_{1}, λ_{0}, the size of the hidden layer N_{1}, and the size of the training set P) by comparing the experimental and predicted generalization error. The very good agreement between the effective theory and the experiments represents an indication that global rescaling of the infinite-width kernel is a main physical mechanism for kernel renormalization in fully connected Bayesian standard-scaled shallow networks.

TLR3 preconditioning induces anti-inflammatory and anti-ictogenic effects in mice mediated by the IRF3/IFN-ß axis.

Activation of Toll-like receptor 3 (TLR3) was previously shown to contribute to the generation of epileptic seizures in rodents by evoking a proinflammatory response in the forebrain. This suggests that TLR3 blockade may provide therapeutic effects in epilepsy. We report that brain activation of TLR3 using the synthetic receptor ligand Poly I:C may also result in remarkable dose- and time-dependent inhibitory effects on acute seizures in mice without inducing inflammation. These inhibitory effects are associated with reduced neuronal excitability in the hippocampus as shown by a decrease in the population spike amplitude of CA1 pyramidal neurons following Schaffer collaterals stimulation. TLR3 activation which results in seizure inhibition does not evoke NF-kB-dependent inflammatory molecules or morphological activation of glia, however, it induces the alternative interferon (IFN) regulatory factor (IRF)-3/IFN-ß signaling pathway. IFN-ß reproduced the inhibitory effects of Poly I:C on neuronal excitability in hippocampal slices. Seizure inhibition attained with activation the TLR3-IRF3/IFN-ß axis should be carefully considered when TLR3 are targeted for therapeutic purposes.

Review: Neuroinflammatory pathways as treatment targets and biomarker candidates in epilepsy: emerging evidence from preclinical and clinical studies.

Accumulating evidence indicates an important pathophysiological role of brain inflammation in epilepsy. In this review, we will provide an update of specific inflammatory pathways that have been proposed to be crucial in the underlying molecular mechanisms of epilepsy, including the interleukin-1 receptor/toll-like receptor signalling, cyclooxygenase-2, tumour necrosis factor-alpha, complement signalling and chemokines. Furthermore, by drawing on evidence from preclinical and clinical studies we will discuss the potential of these signalling pathways targets for novel therapeutic interventions that control drug-resistant seizures or have disease-modifying effects. Finally, we will assess the use of these inflammatory pathways as potential biomarkers for the development of epilepsy or to measure the effectiveness of therapeutic interventions.

How the site degree influences quantum probability on inhomogeneous substrates.

We investigate the effect of the node degree and energy E on the electronic wave function for regular and irregular structures, namely, regular lattices, disordered percolation clusters, and complex networks. We evaluate the dependency of the quantum probability for each site on its degree. For a class of biregular structures formed by two disjoint subsets of sites sharing the same degree, the probability P_{k}(E) of finding the electron on any site with k neighbors is independent of E≠0, a consequence of an exact analytical result that we prove for any bipartite lattice. For more general nonbipartite structures, P_{k}(E) may depend on E as illustrated by an exact evaluation of a one-dimensional semiregular lattice: P_{k}(E) is large for small values of E when k is also small, and its maximum values shift towards large values of |E| with increasing k. Numerical evaluations of P_{k}(E) for two different types of percolation clusters and the Apollonian network suggest that this observed feature might be generally valid.

Pharmacological blockade of IL-1ß/IL-1 receptor type 1 axis during epileptogenesis provides neuroprotection in two rat models of temporal lobe epilepsy.

We studied whether pharmacological blockade of the IL-1ß-mediated signaling, rapidly activated in forebrain by epileptogenic injuries, affords neuroprotection in two different rat models of status epilepticus (SE). As secondary outcome, we measured treatment's effect on SE-induced epileptogenesis. IL-1ß signaling was blocked by systemic administration of two antiinflammatory drugs, namely human recombinant IL-1 receptor antagonist (anakinra), the naturally occurring and clinically used competitive IL-1 receptor type 1 antagonist, and VX-765 a specific non-peptide inhibitor of IL-1ß cleavage and release. Antiinflammatory drugs were given 60min after antiepileptic (AED) drug-controlled SE induced by pilocarpine, or 180min after unrestrained electrical SE, for 7days using a protocol yielding therapeutic drug levels in brain. This drug combination significantly decreased both IL-1ß expression in astrocytes and cell loss in rat forebrain. Neuroprotection and the antiinflammatory effect were more pronounced in the electrical SE model. Onset of epilepsy, and frequency and duration of seizures 3months after electrical SE were not significantly modified. Transcriptomic analysis in the hippocampus showed that the combined treatment did not affect the broad inflammatory response induced by SE during epileptogenesis. In particular, the treatment did not prevent the induction of the complement system and Toll-like receptors, both contributing to cell loss and seizure generation. We conclude that the IL-1ß signaling represents an important target for reducing cell loss after SE. The data highlight a new class of clinically tested agents affording neuroprotection after a delayed post-injury intervention. Earlier blockade of this rapid onset inflammatory pathway during SE, or concomitant treatment with antiinflammatory drugs targeting additional components of the broad inflammatory response to SE, or co-treatment with AEDs, is likely to be required for optimizing beneficial outcomes.

Ultrasonography as a guide during vascular access procedures and in the diagnosis of complications.

Vascular access used in the treatment of patients involves central and peripheral vein accesses and arterial accesses. Catheterization of central veins is widely used in clinical practice; it is a necessary part of the treatment of patients in various settings. The most commonly involved vessels are the internal jugular, subclavian, and femoral veins. The mechanical, infectious, and thrombotic complications of central venous catheterization are markedly reduced when the procedure is performed with real-time ultrasound guidance or (to a slightly lesser extent) ultrasound assistance. Ultrasound guidance is also used to create peripheral venous accesses, for catheterization of peripheral veins and for peripheral insertion of central venous catheters. In this setting, it increases the catheterization success rate, especially during difficult procedures (e.g., obese patients, children) and reduces complications such as catheter-related infections and venous thrombosis. Arterial cannulation is used for invasive monitoring of arterial pressure and for access during diagnostic or therapeutic procedures. Ultrasound guidance reduces the risk of catheterization failure and complications. It is especially useful for arterial catheterization procedures performed in the absence of a palpable pulse (e.g., patient in shock, ECMO). Imaging support is being used increasingly to facilitate the creation of vascular accesses under difficult conditions, in part because of the growing use of ultrasonography as a bedside procedure. In clinical settings where patients are becoming increasingly vulnerable as a result of advanced age and/or complex disease, the possibility to reduce the risks associated with these invasive procedures should motivate clinicians to acquire the technical skills needed for routine use of sonographic support during vascular access procedures.

Transport and scaling in quenched two- and three-dimensional Lévy quasicrystals.

We consider correlated Lévy walks on a class of two- and three-dimensional deterministic self-similar structures, with correlation between steps induced by the geometrical distribution of regions, featuring different diffusion properties. We introduce a geometric parameter α, playing a role analogous to the exponent characterizing the step-length distribution in random systems. By a single-long-jump approximation, we analytically determine the long-time asymptotic behavior of the moments of the probability distribution as a function of α and of the dynamic exponent z associated with the scaling length of the process. We show that our scaling analysis also applies to experimentally relevant quantities such as escape-time and transmission probabilities. Extensive numerical simulations corroborate our results which, in general, are different from those pertaining to uncorrelated Lévy-walk models.

[New developments in epileptogenesis and therapeutic perspectives]. / Neue Entwicklungen der Epileptogenese und therapeutische Perspektiven.

Epileptogenesis describes the mechanisms of how epilepsies are generated. We have chosen four areas in which significant progress has been achieved in understanding epileptogenesis. Those are (1) inflammatory processes which play an increasingly important role for the generation of temporal lobe epilepsy with hippocampal sclerosis (TLE with HS), (2) disturbances of intrinsic properties of neuronal compartments, in particular acquired defects of ion channels of which those in dendrites are described here for TLE with HS, (3) epigenetic effects, which affect for example the methylation of promoters and secondarily can change the expression of specific genes in TLE with HS, and finally (4) the epileptogenesis of idiopathic epilepsies which are caused by inborn genetic alterations affecting mainly ion channels. Apart from aspects of basic research, we will describe clinical consequences and therapeutic perspectives.

Interleukin-1 type 1 receptor/Toll-like receptor signalling in epilepsy: the importance of IL-1beta and high-mobility group box 1.

Inflammatory processes in brain tissue have been described in human epilepsy of various aetiologies and in experimental models of seizures. This, together with the anticonvulsant properties of anti-inflammatory therapies both in clinical and in experimental settings, highlights the important role of brain inflammation in the aetiopathogenesis of seizures. Preclinical investigations in experimental models using pharmacological and genetic tools have identified a significant contribution of interleukin-1 (IL-1) type 1 receptor/Toll-like receptor (IL-1R/TLR) signalling to seizure activity. This signalling can be activated by ligands associated with infections (pathogen-associated molecular patterns) or by endogenous molecules, such as proinflammatory cytokines (e.g. IL-1beta) or danger signals [damage-associated molecular patterns, e.g. high-mobility group box 1 (HMGB1)]. IL-1beta and HMGB1 are synthesized and released by astrocytes and microglia in the rodent brain during seizures. Notably, a rapid release of HMGB1 from neurons appears to be triggered by proconvulsant drugs even before seizure occurrence and is involved in their precipitation of seizures. The activation of IL-1R/TLR signalling mediates rapid post-translational changes in N-methyl-d-aspartate-gated ion channels in neurons. A long-term decrease in seizure threshold has also been observed, possibly mediated by transcriptional activation of genes contributing to molecular and cellular plasticity. This emerging evidence identifies specific targets with potential anticonvulsant effects in drug-resistant forms of epilepsy.

Anticonvulsant effects and behavioural outcomes of rAAV serotype 1 vector-mediated neuropeptide Y overexpression in rat hippocampus.

Neuropeptide Y (NPY) is an endogenous peptide with powerful anticonvulsant properties. Its overexpression in the rat hippocampus, mediated by the local application of recombinant adeno-associated viral (rAAV) vectors carrying the human NPY gene, results in significant reduction of seizures in acute and chronic seizure models. In this study, we characterized a more efficient rAAV-NPY vector to improve cell transfection in the injected area. The changes included pseudotyping with the AAV vector serotype 1 (rAAV1), and using the strong constitutive hybrid CBA promoter, which contains a cytomegalovirus enhancer and chicken beta-actin promoter sequences. We compared NPY expression and the associated anticonvulsant effects of this new vector, with those mediated by the former rAAV vector with chimeric serotype 1/2 (rAAV1/2). In addition, we investigated whether rAAV serotype 1 vector-mediated chronic NPY overexpression causes behavioural deficits that may detract from the clinical utility of this therapeutic approach. We report that rAAV-NPY serotype 1 vector has significantly improved anticonvulsant activity when compared with serotype 1/2 vector, as assessed by measuring EEG seizure activity in kainic acid treated rats. rAAV1-mediated NPY overexpression in naive rats did not result in alterations of physiological functions such as learning and memory, anxiety and locomotor activity. In addition, we did not observe glia activation, or humoral immune responses against serotype 1 vector, which could inactivate gene expression. Our findings show that rAAV1-NPY vector with the CBA promoter mediates powerful anticonvulsant effects and seems to be safe in rodents, thus it may be considered a vector of choice for possible clinical applications.

Complex phase ordering of the one-dimensional Heisenberg model with conserved order parameter.

We study the phase-ordering kinetics of the one-dimensional Heisenberg model with conserved order parameter by means of scaling arguments and numerical simulations. We find a rich dynamical pattern with a regime characterized by two distinct growing lengths. Spins are found to be coplanar over regions of a typical size LV(t), while inside these regions smooth rotations associated to a smaller length LC(t) are observed. Two different and coexisting ordering mechanisms are associated to these lengths, leading to different growth laws LV(t) approximately t1/3 and LC(t) approximately t1/4 violating dynamical scaling.

Molecular and functional interactions between tumor necrosis factor-alpha receptors and the glutamatergic system in the mouse hippocampus: implications for seizure susceptibility.

Tumor necrosis factor (TNF)-alpha is a proinflammatory cytokine acting on two distinct receptor subtypes, namely p55 and p75 receptors. TNF-alpha p55 and p75 receptor knockout mice were previously shown to display a decreased or enhanced susceptibility to seizures, respectively, suggesting intrinsic modifications in neuronal excitability. We investigated whether alterations in glutamate system function occur in these naive knockout mice with perturbed cytokine signaling that could explain their different propensity to develop seizures. Using Western blot analysis of hippocampal homogenates, we found that p55(-/-) mice have decreased levels of membrane GluR3 and NR1 glutamate receptor subunits while GluR1, GluR2, GluR6/7 and NR2A/B were unchanged as compared to wild-type mice. In p75(-/-) mice, GluR2, GluR3, GluR6/7 and NR2A/B glutamate receptor subunits were increased in the hippocampus while GluR1 and NR1 did not change. Extracellular single-cell recordings of the electrical activity of hippocampal neurons were carried out in anesthetized mice by standard electrophysiological techniques. Microiontophoretic application of glutamate increased the basal firing rate of hippocampal neurons in p75(-/-) mice versus wild-type mice, and this effect was blocked by 2-amino-5-phosphopentanoic acid and 6-nitro-7-sulfamoyl-benzo(f)quinoxaline-2,3-dione denoting the involvement of N-methyl-D-aspartic acid and AMPA receptors. In p55(-/-) mice, hippocampal neurons responses to glutamate were similar to wild-type mice. Spontaneous glutamate release measured by in vivo hippocampal microdialysis was significantly decreased only in p55(-/-) mice. No changes were observed in KCl-induced glutamate release in both receptor knockout mice strains versus wild-type mice. These findings highlight specific molecular and functional interactions between p55 and p75 receptor-mediated signaling and the glutamate system. These interactions may be relevant for controlling neuronal excitability in physiological and pathological conditions.

Mixtures of strongly interacting bosons in optical lattices.

We investigate the properties of strongly interacting heteronuclear boson-boson mixtures loaded in realistic optical lattices, with particular emphasis on the physics of interfaces. In particular, we numerically reproduce the recent experimental observation that the addition of a small fraction of 41K induces a significant loss of coherence in 87Rb, providing a simple explanation. We then investigate the robustness against the inhomogeneity typical of realistic experimental realizations of the glassy quantum emulsions recently predicted to occur in strongly interacting boson-boson mixtures on ideal homogeneous lattices.

Acute induction of epileptiform discharges by pilocarpine in the in vitro isolated guinea-pig brain requires enhancement of blood-brain barrier permeability.

Systemic application of the muscarinic agonist, pilocarpine, is commonly utilized to induce an acute status epilepticus that evolves into a chronic epileptic condition characterized by spontaneous seizures. Recent findings suggest that the status epilepticus induced by pilocarpine may be triggered by changes in the blood-brain barrier (BBB) permeability. We tested the role of the BBB in an acute pilocarpine model by using the in vitro model brain preparation and compared our finding with in vivo data. Arterial perfusion of the in vitro isolated guinea-pig brain with <1 mM pilocarpine did not cause epileptiform activity, but rather reduced synaptic transmission and induced steady fast (20-25 Hz) oscillatory activity in limbic cortices. These effects were reversibly blocked by co-perfusion of the muscarinic antagonist atropine sulfate (5 microM). Brain pilocarpine measurements in vivo and in vitro suggested modest BBB penetration. Pilocarpine induced epileptiform discharges only when perfused with compounds that enhance BBB permeability, such as bradykinin (n=2) or histamine (n=10). This pro-epileptic effect was abolished when the BBB-impermeable muscarinic antagonist atropine methyl bromide (5 microM) was co-perfused with histamine and pilocarpine. In the absence of BBB permeability enhancing drugs, pilocarpine induced epileptiform activity only after arterial perfusion at concentrations >10 mM. Ictal discharges correlated with a high intracerebral pilocarpine concentration measured by high pressure liquid chromatography. We propose that acute epileptiform discharges induced by pilocarpine treatment in the in vitro isolated brain preparation are mediated by a dose-dependent, atropine-sensitive muscarinic effect promoted by an increase in BBB permeability. Pilocarpine accumulation secondary to BBB permeability changes may contribute to in vivo ictogenesis in the pilocarpine epilepsy model.

Ground-state fidelity and bipartite entanglement in the Bose-Hubbard model.

We analyze the quantum phase transition in the Bose-Hubbard model borrowing two tools from quantum-information theory, i.e., the ground-state fidelity and entanglement measures. We consider systems at unitary filling comprising up to 50 sites and show for the first time that a finite-size scaling analysis of these quantities provides excellent estimates for the quantum critical point. We conclude that fidelity is particularly suited for revealing a quantum phase transition and pinning down the critical point thereof, while the success of entanglement measures depends on the mechanisms governing the transition.

Phase-ordering kinetics on graphs.

We study numerically the phase-ordering kinetics following a temperature quench of the Ising model with single spin-flip dynamics on a class of graphs, including geometrical fractals and random fractals, such as the percolation cluster. For each structure we discuss the scaling properties and compute the dynamical exponents. We show that the exponent a_{chi} for the integrated response function, at variance with all the other exponents, is independent of temperature and of the presence of pinning. This universal character suggests a strict relation between a_{chi} and the topological properties of the networks, in analogy to what is observed on regular lattices.

Ground-state properties of small-size nonlinear dynamical lattices.

We investigate the ground state of a system of interacting particles in small nonlinear lattices with M >or=3 sites, using as a prototypical example the discrete nonlinear Schrödinger equation that has been recently used extensively in the contexts of nonlinear optics of waveguide arrays and Bose-Einstein condensates in optical lattices. We find that, in the presence of attractive interactions, the dynamical scenario relevant to the ground-state and the lowest-energy modes of such few-site nonlinear lattices reveals a variety of nontrivial features that are absent in the large/infinite lattice limits: the single-pulse solution and the uniform solution are found to coexist in a finite range of the lattice intersite coupling where, depending on the latter, one of them represents the ground state; in addition, the single-pulse mode does not even exist beyond a critical parametric threshold. Finally, the onset of the ground-state (modulational) instability appears to be intimately connected with a nonstandard ("double transcritical") type of bifurcation that, to the best of our knowledge, has not been reported previously in other physical systems.

Topological filters and high-pass/low-pass devices for solitons in inhomogeneous networks.

We show that, by inserting suitable finite networks at a site of a chain, it is possible to realize filters and high-pass/low-pass devices for solitons propagating along the chain. The results are presented in the framework of coupled optical waveguides; possible applications to different contexts, such as photonic lattices and Bose-Einstein condensates in optical networks are also discussed. Our results provide a first step in the control of the soliton dynamics through the network topology.