White matter and task-switching in young adults: A Diffusion Tensor Imaging study

The capacity to flexibly switch between different task rules has been previously associated with distributed fronto-parietal networks, predominantly in the left hemisphere for phasic switching sub-processes, and in the right hemisphere for more tonic aspects of task-switching, such as rule maintenance and management. It is thus likely that the white matter (WM) connectivity between these regions is critical in sustaining the flexibility required by task-switching. This study examined the relationship between WM microstructure in young adults and task-switching performance in different paradigms: classical shape-color, spatial and grammatical tasks. The main results showed an association between WM integrity in anterior portions of the corpus callosum (genu and body) and a sustained measure of task-switching performance. In particular, a higher fractional anisotropy and a lower radial diffusivity in these WM regions were associated with smaller mixing costs both in the spatial task-switching paradigm and in the shape-color one, as confirmed by a conjunction analysis. No association was found with behavioral measures obtained in the grammatical task-switching paradigm. The switch costs, a measure of phasic switching processes, were not correlated with WM microstructure in any task. This study shows that a more efficient inter-hemispheric connectivity within the frontal lobes favors sustained task-switching processes, especially with task contexts embedding non-verbal components

First detection of Borrelia miyamotoi in Ixodes ricinus ticks from northern Italy.

Borrelia miyamotoi is a spirochete transmitted by several ixodid tick species. It causes a relapsing fever in humans and is currently considered as an emerging pathogen. In Europe, B. miyamotoi seems to occur at low prevalence in Ixodes ricinus ticks but has a wide distribution. Here we report the first detection of B. miyamotoi in Ixodes ricinus ticks collected in two independent studies conducted in 2016 in the north-eastern and north-western Alps, Italy

Compressed Sensing: a new paradigm for Rapid MR Imaging

La teoria del Compressed Sensing si propone di risolvere il problema della ricostruzione di una immagine da un campionamento in frequenza incompleto, sfruttando la proprietà di sparsità di molte immagini. Le immagini da risonanza magnetica (MR) offrono un campo di applicazione a questa teoria, con possibili significativi miglioramenti in termini di tempi di acquisizione e qualità dell'immagin

Diversity indices and normalization approaches in microbiome studies

This thesis explores human microbiota, by investigating how to consistently measure biodiversity, both within and between different body sites, and how to correctly compare and normalize samples. In this work we propose a new method, called zero imputation, that tries to account for data sparsity; it proves to outperform common normalization approaches in recovering true data richness and relative abundances. We also develop a microbiome data simulator, useful to test all the methods reviewe

Measuring the diversity of the human microbiota with targeted next-generation sequencing

The human microbiota is a complex ecological community of commensal, symbiotic and pathogenic microorganisms harboured by the human body. Next-generation sequencing (NGS) technologies, in particular targeted amplicon sequencing of the 16S ribosomal RNA gene (16S-seq), are enabling the identification and quantification of human-resident microorganisms at unprecedented resolution, providing novel insights into the role of the microbiota in health and disease. Once microbial abundances are quantified through NGS data analysis, diversity indices provide valuable mathematical tools to describe the ecological complexity of a single sample or to detect species differences between samples. However, diversity is not a determined physical quantity for which a consensus definition and unit of measure have been established, and several diversity indices are currently available. Furthermore, they were originally developed for macroecology and their robustness to the possible bias introduced by sequencing has not been characterized so far. To assist the reader with the selection and interpretation of diversity measures, we review a panel of broadly used indices, describing their mathematical formulations, purposes and properties, and characterize their behaviour and criticalities in dependence of the data features using simulated data as ground truth. In addition, we make available an R package, DiversitySeq, which implements in a unified framework the full panel of diversity indices and a simulator of 16S-seq data, and thus represents a valuable resource for the analysis of diversity from NGS count data and for the benchmarking of computational methods for 16S-seq

The neural substrate of spatial memory stabilization depends on the distribution of the training sessions

Distributed training is known to lead to more robust memory formation as compared to training experiences with short intervals. Although this phenomenon, termed distributed practice effect, ubiquitous over a wide variety of tasks and organisms, has long been known by psychologists, its neurobiological underpinning is still poorly understood. Using the striatum as a model system here we tested the hypothesis that the ability of distributed training to optimize memory might depend upon the recruitment of different neural substrates compared to those engaged by massed training. First, by contrasting the medial and the lateral domains of the dorsal striatum after massed and distributed training we demonstrated that neuronal activity, as assessed using c-Fos expression, is differentially affected by the training protocol in the two striatal subregions. Next, by blocking the AMPA receptors before recall we provide evidence to support a selective role of the medial and the lateral striatum in the storage of information acquired respectively by massed and distributed training. Finally, we found that optogenetic stimulation of the dorsolateral striatum during massed training enables the formation of an enduring memory similarly to what is observed with distributed learning. Overall, these findings identify a possible mechanism for the distributed practice effect, a still poorly understood aspect of learning

Vaccine immune pressure influences viral population complexity of avian influenza virus during infection

Vaccines are useful tools to control influenza A virus infection in poultry, but they need to be periodically reformulated to guarantee appropriate protection from infection and to limit viral replication and circulation, which could favour the emergence of new variants. In this study, a deep sequencing approach was used to characterize and follow the evolution of the hemagglutinin of the H5N1 highly pathogenic avian influenza viral population in infected animals vaccinated with two vaccines conferring different protection levels. Results from this preliminary investigation suggested that the evolution of the viral population, as well as the abundance and heterogeneity of minority variants could be influenced by the immune pressure conferred by vaccination