Intermittency properties in a temporal lobe epilepsy model.

Neuronal synchronization is important for communication between brain regions and plays a key role in learning. However, changes in connectivity can lead to hyper-synchronized states related to epileptic seizures that occur intermittently with asynchronous states. The activity-regulated cytoskeleton-associated protein (ARC) is related to synaptic alterations which can lead to epilepsy.

Particle-swarm based modelling reveals two distinct classes of CRH neurons.

Electrophysiological recordings can provide detailed information of single neurons' dynamical features and shed light on their response to stimuli. Unfortunately, rapidly modelling electrophysiological data for inferring network-level behaviours remains challenging. Here, we investigate how modelled single neuron dynamics leads to network-level responses in the paraventricular nucleus of the hypothalamus (PVN), a critical nucleus for the mammalian stress response.

Influence of Delayed Conductance on Neuronal Synchronization.

In the brain, the excitation-inhibition balance prevents abnormal synchronous behavior. However, known synaptic conductance intensity can be insufficient to account for the undesired synchronization. Due to this fact, we consider time delay in excitatory and inhibitory conductances and study its effect on the neuronal synchronization.

Frequency cluster formation and slow oscillations in neural populations with plasticity.

We report the phenomenon of frequency clustering in a network of Hodgkin-Huxley neurons with spike timing-dependent plasticity. The clustering leads to a splitting of a neural population into a few groups synchronized at different frequencies. In this regime, the amplitude of the mean field undergoes low-frequency modulations, which may contribute to the mechanism of the emergence of slow oscillations of neural activity observed in spectral power of local field potentials or electroencephalographic signals at high frequencies.

Bistable Firing Pattern in a Neural Network Model.

Excessively high, neural synchronization has been associated with epileptic seizures, one of the most common brain diseases worldwide. A better understanding of neural synchronization mechanisms can thus help control or even treat epilepsy. In this paper, we study neural synchronization in a random network where nodes are neurons with excitatory and inhibitory synapses, and neural activity for each node is provided by the adaptive exponential integrate-and-fire model.

Recurrence quantification analysis for the identification of burst phase synchronisation.

In this work, we apply the spatial recurrence quantification analysis (RQA) to identify chaotic burst phase synchronisation in networks. We consider one neural network with small-world topology and another one composed of small-world subnetworks. The neuron dynamics is described by the Rulkov map, which is a two-dimensional map that has been used to model chaotic bursting neurons.

Synchronous behaviour in network model based on human cortico-cortical connections.

Objective: We consider a network topology according to the cortico-cortical connection network of the human brain, where each cortical area is composed of a random network of adaptive exponential integrate-and-fire neurons.

Approach: Depending on the parameters, this neuron model can exhibit spike or burst patterns. As a diagnostic tool to identify spike and burst patterns we utilise the coefficient of variation of the neuronal inter-spike interval.

Inference of topology and the nature of synapses, and the flow of information in neuronal networks.

The characterization of neuronal connectivity is one of the most important matters in neuroscience. In this work, we show that a recently proposed informational quantity, the causal mutual information, employed with an appropriate methodology, can be used not only to correctly infer the direction of the underlying physical synapses, but also to identify their excitatory or inhibitory nature, considering easy to handle and measure bivariate time series. The success of our approach relies on a surprising property found in neuronal networks by which nonadjacent neurons do "understand" each other (positive mutual information), however, this exchange of information is not capable of causing effect (zero transfer entropy).

ADDUCTOR POLLICIS MUSCLE THICKNESS AND PREDICTION OF POSTOPERATIVE MORTALITY IN PATIENTS WITH STOMACH CANCER.

Background: Malnutrition is very prevalent in patients with gastric cancer and increases the risk of morbidity and mortality. Adductor pollicis muscle thickness (APMT) appears as an important objective, quick, inexpensive and noninvasive measure to assess the muscle compartment.

Aim: To compare APMT and other nutritional assessment methods and to correlate these methods with postoperative mortality.

Nutritional assessment methods as predictors of postoperative mortality in gastric cancer patients submitted to gastrectomy.

Objectives: to determine the nutritional evaluation method that best predicts mortality in 90 days of patients submitted to gastrectomy for gastric cancer.

Methods: we conducted a prospective study with 44 patients with gastric cancer, stages II to IIIa, of whom nine were submitted to partial gastrectomy, 34 to total gastrectomy, and one to esophago-gastrectomy. All patients were nutritionally evaluated through the same protocol, up to 72h after hospital admission.

Synchronised firing patterns in a random network of adaptive exponential integrate-and-fire neuron model.

We have studied neuronal synchronisation in a random network of adaptive exponential integrate-and-fire neurons. We study how spiking or bursting synchronous behaviour appears as a function of the coupling strength and the probability of connections, by constructing parameter spaces that identify these synchronous behaviours from measurements of the inter-spike interval and the calculation of the order parameter. Moreover, we verify the robustness of synchronisation by applying an external perturbation to each neuron.

Spike timing-dependent plasticity induces non-trivial topology in the brain.

We study the capacity of Hodgkin-Huxley neuron in a network to change temporarily or permanently their connections and behavior, the so called spike timing-dependent plasticity (STDP), as a function of their synchronous behavior. We consider STDP of excitatory and inhibitory synapses driven by Hebbian rules. We show that the final state of networks evolved by a STDP depend on the initial network configuration.

Suppression of phase synchronisation in network based on cat's brain.

We have studied the effects of perturbations on the cat's cerebral cortex. According to the literature, this cortex structure can be described by a clustered network. This way, we construct a clustered network with the same number of areas as in the cat matrix, where each area is described as a sub-network with a small-world property.

Retinol, β-carotene and oxidative stress in systemic inflammatory response syndrome.

Objective: patients suffering systemic inflammatory response syndrome (SIRS) constitute a group susceptible to elevated levels of oxidative stress. This study's aim is to evaluate the state of oxidative stress and levels of serum retinol and β-carotene in these patients.

Methods: forty-six patients were divided into 2 groups: those those without diet (G1; n=18) and those with enteral nutritional support (G2; n=28).

Effects of supplementation of antioxidant vitamins and lipid peroxidation in critically ill patients.

Introduction: Critical patients present systemic inflammatory process that can be followed by decrease in plasma concentrations of antioxidant vitamins.

Objective: [corrected] The aim of this study was to evaluate the effect of the supplementation of antioxidant vitamins in critical patients and their relation with lipid peroxidation.

Methods: 23 patients went on a standard diet (G1) and 11 went on a diet with daily supplementation of 10,000 IU of vitamin A, 400 mg of vitamin E and 600 mg of vitamin C (G2).

Suppression of bursting synchronization in clustered scale-free (rich-club) neuronal networks.

Functional brain networks are composed of cortical areas that are anatomically and functionally connected. One of the cortical networks for which more information is available in the literature is the cat cerebral cortex. Statistical analyses of the latter suggest that its structure can be described as a clustered network, in which each cluster is a scale-free network possessing highly connected hubs.

Preoperative nutritional assessment and prognosis in patients with foregut tumors.

Malnourished patients with gastrointestinal tumours are at risk for postoperative complications and death. The aim of this study was to determine which nutritional assessment method better predicts outcome. Seventy-four patients, 45 men and 29 women; mean (SD) age of 63 (102) yr (range = 34 to 83), undergoing surgical resections for esophageal (n = 19) gastric (n = 43) and pancreatic (n = 12) tumors were preoperatively assessed by Patient Generated Subjective Global Assessment, anthropometry, and by laboratory sampling.

Phase synchronization of bursting neurons in clustered small-world networks.

We investigate the collective dynamics of bursting neurons on clustered networks. The clustered network model is composed of subnetworks, each of them presenting the so-called small-world property. This model can also be regarded as a network of networks.

Serum concentrations of vitamin A and oxidative stress in critically ill patients with sepsis.

Introduction: Sepsis is one of the main causes of mortality in patients in Intensive Care Units. As a result of the systemic inflammatory response and of the decrease of the aerobic metabolism in sepsis, the oxidative stress occurs. Vitamin A is recognized by the favorable effect that it exerts on the immune response to infections and antioxidant action.

Adductor pollicis muscle: a new anthropometric parameter.

Purpose: To measure the thickness of adductor pollicis muscle in healthy adults. This measurement will be used as a nutritional anthropometric parameter in further studies.

Subjects And Method: Four hundred and twenty-one healthy adults were studied, 209 men and 212 women, with ages ranging from 18 to 87 years, living in Rio de Janeiro.

The thickness of the adductor pollicis muscle reflects the muscle compartment and may be used as a new anthropometric parameter for nutritional assessment.

Purpose Of Review: Contraction of the adductor pollicis muscle after electrical stimulation (electromyogram) or dynamometry (hand-grip tests) has been evaluated in a variety of clinical conditions as a parameter to assess nutritional status. However, adductor pollicis muscle thickness has not been investigated as an anthropometric parameter.

Recent Findings: Prolonged immobilization and non-use of lower and upper limb muscles causes atrophy.