Towards high-quality simultaneous EEG-fMRI at 7T: Detection and reduction of EEG artifacts due to head motion.

The enhanced functional sensitivity offered by ultra-high field imaging may significantly benefit simultaneous EEG-fMRI studies, but the concurrent increases in artifact contamination can strongly compromise EEG data quality. In the present study, we focus on EEG artifacts created by head motion in the static B0 field. A novel approach for motion artifact detection is proposed, based on a simple modification of a commercial EEG cap, in which four electrodes are non-permanently adapted to record only magnetic induction effects. Simultaneous EEG-fMRI data were acquired with this setup, at 7T, from healthy volunteers undergoing a reversing-checkerboard visual stimulation paradigm. Data analysis assisted by the motion sensors revealed that, after gradient artifact correction, EEG signal variance was largely dominated by pulse artifacts (81-93%), but contributions from spontaneous motion (4-13%) were still comparable to or even larger than those of actual neuronal activity (3-9%). Multiple approaches were tested to determine the most effective procedure for denoising EEG data incorporating motion sensor information. Optimal results were obtained by applying an initial pulse artifact correction step (AAS-based), followed by motion artifact correction (based on the motion sensors) and ICA denoising. On average, motion artifact correction (after AAS) yielded a 61% reduction in signal power and a 62% increase in VEP trial-by-trial consistency. Combined with ICA, these improvements rose to a 74% power reduction and an 86% increase in trial consistency. Overall, the improvements achieved were well appreciable at single-subject and single-trial levels, and set an encouraging quality mark for simultaneous EEG-fMRI at ultra-high field.

Differential patterns of functional and structural plasticity within and between inferior frontal gyri support training-induced improvements in inhibitory control proficiency.

Ample evidence indicates that inhibitory control (IC), a key executive component referring to the ability to suppress cognitive or motor processes, relies on a right-lateralized fronto-basal brain network. However, whether and how IC can be improved with training and the underlying neuroplastic mechanisms remains largely unresolved. We used functional and structural magnetic resonance imaging to measure the effects of 2 weeks of training with a Go/NoGo task specifically designed to improve frontal top-down IC mechanisms. The training-induced behavioral improvements were accompanied by a decrease in neural activity to inhibition trials within the right pars opercularis and triangularis, and in the left pars orbitalis of the inferior frontal gyri. Analyses of changes in brain anatomy induced by the IC training revealed increases in grey matter volume in the right pars orbitalis and modulations of white matter microstructure in the right pars triangularis. The task-specificity of the effects of training was confirmed by an absence of change in neural activity to a control working memory task. Our combined anatomical and functional findings indicate that differential patterns of functional and structural plasticity between and within inferior frontal gyri enhanced the speed of top-down inhibition processes and in turn IC proficiency. The results suggest that training-based interventions might help overcoming the anatomic and functional deficits of inferior frontal gyri manifesting in inhibition-related clinical conditions. More generally, we demonstrate how multimodal neuroimaging investigations of training-induced neuroplasticity enable revealing novel anatomo-functional dissociations within frontal executive brain networks. Hum Brain Mapp 36:2527-2543, 2015. © 2015 Wiley Periodicals, Inc.

Development of the ability to inhibit a prepotent response: influence of working memory and processing speed.

This study aimed to examine developmental trends in response inhibition during childhood and to control for possible developmental influence of other basic cognitive processes (such as working memory and processing speed). In addition, we explored the relationships between response inhibition, working memory, and processing speed, as they are thought to be integral to cognitive control. Therefore, we assessed these three cognitive abilities in 159 children aged from 5 to 12. Results showed an improvement in response inhibition ability from 5 to 10 years of age. This improvement remained significant after controlling for the influence of working memory and processing speed. Furthermore, the developmental relationships showed an early differentiation between response inhibition, working memory, and processing speed. Thus, these processes were independent and need to be treated as such in further studies.

Growth and magnetic characterization of Co nanoparticles obtained by femtosecond pulsed laser deposition.

We present a detailed study on the morphology and magnetic properties of Co nanostructures deposited onto oxidized Si substrates by femtosecond pulsed laser deposition. Generally, Co disks of nanometric dimensions are obtained just above the ablation threshold, with a size distribution characterized by an increasingly larger number of disks as their size diminishes, and with a maximum disk size that depends on the laser power density. In Au/Co/Au structures, in-plane magnetic anisotropy is observed in all cases, with no indication of superparamagnetism regardless of the amount of material or the laser power density. Magnetic force microscopy observations show coexistence of single-domain and vortex states for the magnetic domain structure of the disks. Superconducting quantum interference device magnetometry and x-ray magnetic circular dichroism measurements point to saturation magnetization values lower than the bulk, probably due to partial oxidation of the Co resulting from incomplete coverage by the Au capping layer.

Environmental activity of bacteria degrading pollutants

Une des meilleures techniques pour décontaminer l'environnement d'éléments toxiques (comme par exemple le dibenzofuan, DBF et le 4-chlorophenol, 4CP) déposés par l'homme, à bas coûts et sans le perturber considérablement, est sans doute la biorémédiation, et particulièrement la bioaugmentation. Malheureusement, si plusieurs microorganismes ont démontré leur efficacité à dégrader les composés toxiques en conditions de laboratoire, plusieurs tentatives afin de les utiliser dans l'environnement n'ont pas abouti. Ces échecs sont probablement le résultat des pauvres connaissances des réactions de ces mêmes microorganismes dans l'environnement. L'objectif de mon travail a été de mieux comprendre les réponses de ces bactéries au niveau de leurs gènes lorsqu'elles sont introduites ou prospèrent dans des conditions plus proches de la réalité, mais encore suffisamment contrôlées pour pouvoir élucider leur comportement. Le fait de résister à des conditions de sécheresse a été considéré en tant que facteur clé dans la survie des bactéries amenées à être utilisées pour la biorémédiation; cela implique une série de mécanismes utilisés par la cellule pour faire face au stress hydrique. Le chapitre II, par une approche métagénomique, compare les réactions de trois souches prometteuses pour la biorémédiation (Arthrobacter chlorophenolicus A6, Sphingomonas wittichii RW1 and Pseudomonas veronii 1YdBTEX2) vis-à-vis du stress hydrique simulé en conditions de laboratoire. L'objectif ici est de découvrir et de décrire les stratégies de résistance au stress, communes ou spécifiques, employées par les bactéries. Mes résultats montrent que les trois souches ont des sensibilités différentes au stress hydrique. Entre les traits communs trouvés, il y a une diminution de l'expression des gènes flagellaires ainsi qu'une augmentation de l'expression de solutes compatibles, mais qui sont souche-spécifiques. J'ai étudié plus en détail la réponse génomique de RW1 par rapport aux inoculations ainsi que sa croissance dans le sable contaminé et non-stérile (chapitre III), et je les ai comparé à des cultures en milieu liquide. Mes résultats indiquent que RW1 peut résister efficacement et peut croître dans des conditions presque sèches et peut également dégrader le contaminant (DBF, dans le cas présent) si les pré-cultures sont réalisées dans le même type de contaminant. Par contre, notre hypothèse du chapitre II se révèle fausse car le comportement de RW1 est très diffèrent de celui observé dans des conditions avec stress hydrique induit par l'addition de sel ou de PEG. Plus intéressant, les réponses de RW1 en milieu liquide sont très différentes de celles observées dans le sable, révélant ainsi que cette souche peut reconnaître le milieu dans lequel elle se trouve. Les mêmes expériences en sable contaminé, cette fois-ci avec 4CP, ont été réalisées pour A6 (chapitre IV) dans l'espoir de compléter la comparaison entre le stress hydrique et l'adaptation dans le sol. Malheureusement, il n'a pas été possible d'obtenir d'échantillons de bonne qualité pour les hybridations des microarrays afin d'étudier la réponse transcriptionnelle dans les différentes phases de croissance dans le sable (contaminé ou non). Toutefois, j'ai appris qu'Arthrobacter ne peut pas croitre dans les sols hautement contaminés si les conditions du sol sont très sèches, elles ont en effet besoin de suffisamment d'eau pour dégrader des quantités importantes de 4CP. Ces observations dirigent l'attention sur le fait que les études sur l'efficacité de l'inoculation de bactéries doivent être testées dans des conditions le plus proche possible de l'environnement ciblé, tout comme les concentrations optimales pour l'inoculum. Finalement, nous avons étudié le comportement de A6 dans la phytosphère avec deux dégrés d'humidité (chapitre V). A6 ne montre pas de réaction particulière face aux changements d'humidité, et à nouveau, ces réponses ne peuvent être liées aux changements d'expression des gènes observées dans les conditions de stress hydrique simulées. Cette étude a permis d'identifier la présence de composés phénoliques dans les feuilles qui peuvent potentiellement améliorer les propriétés de dégradation ou qui permettent d'effectuer de façon plus rapide la réaction de dégradation des contaminants dans un processus de phytoremédiation par A. chlorophenolicus.

Distinct contributions of Brodmann areas 1 and 2 to body ownership.

Although body ownership-i.e. the feeling that our bodies belong to us-modulates activity within the primary somatosensory cortex (S1), it is still unknown whether this modulation occurs within a somatotopically defined portion of S1. We induced an illusory feeling of ownership for another person's finger by asking participants to hold their palm against another person's palm and to stroke the two joined index fingers with the index and thumb of their other hand. This illusion (numbness illusion) does not occur if the stroking is performed asynchronously or by the other person. We combined this somatosensory paradigm with ultra-high field functional magnetic resonance imaging finger mapping to study whether illusory body ownership modulates activity within different finger-specific areas of S1. The results revealed that the numbness illusion is associated with activity in Brodmann area (BA) 1 within the representation of the finger stroking the other person's finger and in BA 2 contralateral to the stroked finger. These results show that changes in bodily experience modulate the activity within certain subregions of S1, with a different finger-topographical selectivity between the representations of the stroking and of the stroked hand, and reveal that the high degree of somatosensory specialization in S1 extends to bodily self-consciousness.

Regulatable and modulable background expression control in prokaryotic synthetic circuits by auxiliary repressor binding sites.

Expression control in synthetic genetic circuitry, for example, for construction of sensitive biosensors, is hampered by the lack of DNA parts that maintain ultralow background yet achieve high output upon signal integration by the cells. Here, we demonstrate how placement of auxiliary transcription factor binding sites within a regulatable promoter context can yield an important gain in signal-to-noise output ratios from prokaryotic biosensor circuits. As a proof of principle, we use the arsenite-responsive ArsR repressor protein from Escherichia coli and its cognate operator. Additional ArsR operators placed downstream of its target promoter can act as a transcription roadblock in a distance-dependent manner and reduce background expression of downstream-placed reporter genes. We show that the transcription roadblock functions both in cognate and heterologous promoter contexts. Secondary ArsR operators placed upstream of their promoter can also improve signal-to-noise output while maintaining effector dependency. Importantly, background control can be released through the addition of micromolar concentrations of arsenite. The ArsR-operator system thus provides a flexible system for additional gene expression control, which, given the extreme sensitivity to micrograms per liter effector concentrations, could be applicable in more general contexts.

23

The aim of this chapter is to provide an understanding of retirement adjustment by specifically focusing on meaning in life for retirees and meaningful work for older workers who are close to retirement. After a first outline of global issues of aging and work, we approach transition to retirement from the standpoint of sustainable careers within its main dimensions of continuity and importance of personal agency. Next, we review and synthesize literature on meaningful work and meaning in life, distinguishing three levels that constitute meaningful work and five dimensions of meaning in life. To illustrate our points, we present quotations from semi-structured interviews realized with Swiss older workers who were going to retire within a few months. Then, we describe ways to promote meaningful work for older workers and how to create a new meaning or to pursue a previous meaning as a retiree. Finally, we suggest ways individuals, organizations, and career counselors can facilitate a meaningful transition to retirement.

Genetic associations at 53 loci highlight cell types and biological pathways relevant for kidney function.

Reduced glomerular filtration rate defines chronic kidney disease and is associated with cardiovascular and all-cause mortality. We conducted a meta-analysis of genome-wide association studies for estimated glomerular filtration rate (eGFR), combining data across 133,413 individuals with replication in up to 42,166 individuals. We identify 24 new and confirm 29 previously identified loci. Of these 53 loci, 19 associate with eGFR among individuals with diabetes. Using bioinformatics, we show that identified genes at eGFR loci are enriched for expression in kidney tissues and in pathways relevant for kidney development and transmembrane transporter activity, kidney structure, and regulation of glucose metabolism. Chromatin state mapping and DNase I hypersensitivity analyses across adult tissues demonstrate preferential mapping of associated variants to regulatory regions in kidney but not extra-renal tissues. These findings suggest that genetic determinants of eGFR are mediated largely through direct effects within the kidney and highlight important cell types and biological pathways.

Genome-wide Association Studies Identify Genetic Loci Associated With Albuminuria in Diabetes.

Elevated concentrations of albumin in the urine, albuminuria, are a hallmark of diabetic kidney disease and are associated with an increased risk for end-stage renal disease and cardiovascular events. To gain insight into the pathophysiological mechanisms underlying albuminuria, we conducted meta-analyses of genome-wide association studies and independent replication in up to 5,825 individuals of European ancestry with diabetes and up to 46,061 without diabetes, followed by functional studies. Known associations of variants in CUBN, encoding cubilin, with the urinary albumin-to-creatinine ratio (UACR) were confirmed in the overall sample (P = 2.4 × 10(-10)). Gene-by-diabetes interactions were detected and confirmed for variants in HS6ST1 and near RAB38/CTSC. Single nucleotide polymorphisms at these loci demonstrated a genetic effect on UACR in individuals with but not without diabetes. The change in the average UACR per minor allele was 21% for HS6ST1 (P = 6.3 × 10(-7)) and 13% for RAB38/CTSC (P = 5.8 × 10(-7)). Experiments using streptozotocin-induced diabetic Rab38 knockout and control rats showed higher urinary albumin concentrations and reduced amounts of megalin and cubilin at the proximal tubule cell surface in Rab38 knockout versus control rats. Relative expression of RAB38 was higher in tubuli of patients with diabetic kidney disease compared with control subjects. The loci identified here confirm known pathways and highlight novel pathways influencing albuminuria.

Maladaptive emotion regulation strategies and stress sensitivity mediate the relation between adverse life events and attenuated positive psychotic symptoms.

INTRODUCTION: There is now solid evidence for a relation between adverse life events (ALE) and psychotic symptoms in patients with psychosis and in the general population. A recent study has shown that this relation may be partially mediated by stress sensitivity, suggesting the influence of other factors. The aim of this study was to assess the mediation effect of emotion regulation strategies and stress sensitivity in the relation between ALE and attenuated positive psychotic symptoms (APPS) in the general population. METHODS: Hundred and twelve healthy volunteers were evaluated with measures of APPS, emotion regulation strategies, ALE and stress sensitivity. RESULTS: Results demonstrated that the relation between ALE, hallucination and delusion proneness was completely mediated by maladaptive emotion regulation strategies, but not by stress sensitivity. However, in addition to maladaptive emotion regulation strategies, stress sensitivity demonstrated a mediation effect between ALE and attenuated positive psychotic positive symptoms when positive psychotic symptoms were grouped together. CONCLUSIONS: There are probably several possible trajectories leading to the formation of positive psychotic symptoms and the results of the present study reveal that one such trajectory may involve the maladaptive regulation of negative emotions alongside a certain general vulnerability after experiencing ALE.