Neuronal effects following working memory training

AbstractThere is accumulating evidence that training working memory (WM) leads to beneficial effects in tasks that were not trained, but the mechanisms underlying this transfer remain elusive. Brain imaging can be a valuable method to gain insights into such mechanisms. Here, we discuss the impact of cognitive training on neural correlates with an emphasis on studies that implemented a WM intervention. We focus on changes in activation patterns, changes in resting state connectivity, changes in brain structure, and changes in the dopaminergic system. Our analysis of the existing literature reveals that there is currently no clear pattern of results that would single out a specific neural mechanism underlying training and transfer. We conclude that although brain imaging has provided us with information about the mechanisms of WM training, more research is needed to understand its neural impact

Increase of Fungal Endocarditis in Children

Background:: Infective endocarditis (IE) is a rare and feared infection that mainly occurs in patients with underlying cardiac disease or altered function of the immune system. Recent epidemiological data on both sepsis and nosocomial infections indicate a rise in gram-negative bacterial and fungal infection, particularly in patients requiring critical care support. This study sought to characterize the change in the spectrum of IE encountered in a single pediatric tertiary care center during the last 18 years, to evaluate emergence of fungal IE and to identify contributing factors. Patients and Methods:: Review of all cases of IE diagnosed between January 1986 and August 2003 at a single university children's hospital. Patients were distributed between two equal time periods and compared according to the era of IE diagnosis. Results:: In 43 patients, 44 episodes of IE were identified with most cases occurring in children with congenital or acquired heart disease. The annual number of diagnosed cases fluctuated during the study (mean 2.4 cases/year). Blood or specimen cultures were positive in 34 cases (77%) with gram-positive organisms most frequently observed (n = 20, 44.4%). Fungal IE cases (n = 9, 20%) occurred preferentially during the second period (p < 0.03), and were more common in children with noncardiac diseases (p = 0.023). Factors associated with fungal IE were the use of broad-spectrum antibiotics (p < 0.001) and the presence of an infected central venous catheter (p = 0.01). Overall mortality did not differ between the two eras. Conclusion:: The incidence of fungal IE seems to have significantly increased in more recent years. Use of broadspectrum antibiotics for prolonged time or/and central venous catheters were identified as predisposing factors to fungal infective endocarditi

High Precision Surface Structuring with Ultra-Short Laser Pulses and Synchronized Mechanical Axes

For surface and 3D structuring in a 2.5D process, ultra-short pulsed laser systems are mostly used in combination with mechanical axes, whereas the mechanical axes can include electrical motor as well as beam deflecting systems like a galvo scanner. The motion of the axes is synchronized with the clock of the laser pulses, by a modification of the electronic axes control. This work shows the scalability of the ablation process up to MHz-regime in relation to surface quality and ablation efficiency, drilling of thin foils without any heat accumulation and deforming problems of the foil. Furthermore the transfer of the machining strategy from a synchronized galvo scanner to a rotating cylinder setup is shown

Heat accumulation effects in laser processing of diamond-like nanocomposite films with bursts of femtosecond pulses

In this paper we have investigated the burst mode (BM) ablation and surface structuring of diamond-like nanocomposite (DLN) a-C:H:Si:O films with femtosecond laser pulses (wavelength λ=515 nm, pulse duration τ=320 fs, pulse repetition rate f=100 kHz) under different scanning conditions (single spots, linear structures). The pulse separation in the bursts is 25 ns (intra-burst frequency f=40 MHz) and the pulse number is varied from 1 to 8. The ablation depth and specific ablation rates (μm3/μJ) are found to be higher for the burst mode compared to single pulse irradiation, increasing with the pulse number in the burst. The obtained experimental data of the higher ablation efficiency are shown to correlate with computer simulations of the BM ablation. In correlation with the ablation findings, Raman spectra of single spots and microgrooves have evidenced a growing graphitization of amorphous film structure with the pulse number in the bursts (at equal energy deposited into the films). Contact-mode atomic force microscopy (AFM) is applied to reveal an influence of the BM processing on the surface properties (nanoscale relief, friction) of laser-structured films. Based on the ablation and Raman data analysis, AFM examination of ablated/redeposited layers and computer simulations of the burst mode ablation, the heat accumulation is identified as the main factor responsible for the enhanced ablation efficiency during the BM processing of DLN films. In addition, results of high precision surface microstructuring of DLN films in the burst mode are presented

Sub-Threshold Fabrication of Laser-Induced Periodic Surface Structures on Diamond-like Nanocomposite Films with IR Femtosecond Pulses

In the paper, we study the formation of laser-induced periodic surface structures (LIPSS) on diamond-like nanocomposite (DLN) a-C:H:Si:O films during nanoscale ablation processing at low fluences—below the single-pulse graphitization and spallation thresholds—using an IR fs-laser (wavelength 1030 nm, pulse duration 320 fs, pulse repetition rate 100 kHz, scanning beam velocity 0.04–0.08 m/s). The studies are focused on microscopic analysis of the nanostructured DLN film surface at different stages of LIPSS formation and numerical modeling of surface plasmon polaritons in a thin graphitized surface layer. Important findings are concerned with (i) sub-threshold fabrication of high spatial frequency LIPSS (HSFL) and low spatial frequency LIPSS (LSFL) under negligible surface graphitization of hard DLN films, (ii) transition from the HSFL (periods of 140 ± 30 and 230 ± 40 nm) to LSFL (period of 830–900 nm) within a narrow fluence range of 0.21–0.32 J/cm2, (iii) visualization of equi-field lines by ablated nanoparticles at an initial stage of the LIPSS formation, providing proof of larger electric fields in the valleys and weaker fields at the ridges of a growing surface grating, (iv) influence of the thickness of a laser-excited glassy carbon (GC) layer on the period of surface plasmon polaritons excited in a three-layer system “air/GC layer/DLN film”

Impact of Prenatal Stress on Offspring Glucocorticoid Levels: A Phylogenetic Meta-analysis Across 14 Vertebrate Species

Prenatal exposure to maternal stress is commonly associated with variation in Hypothalamic Pituitary Adrenal (HPA)-axis functioning in ofspring. However, the strength or consistency of this response has never been empirically evaluated across vertebrate species. Here we meta-analyzed 114 results from 39 studies across 14 vertebrate species using Bayesian phylogenetic mixed-efects models. We found a positive overall efect of prenatal stress on ofspring glucocorticoids (d’=0.43) though the 95% Highest Posterior Density Interval overlapped with 0 (−0.16–0.95). Meta-regressions of potential moderators highlighted that phylogeny and life history variables predicted relatively little variation in efect size. Experimental studies (d’=0.64) produced stronger efects than observational ones (d’=−0.01), while prenatal stress afected glucocorticoid recovery following ofspring stress exposure more strongly (d’=0.75) than baseline levels (d’=0.48) or glucocorticoid peak response (d’=0.36). These fndings are consistent with the argument that HPA-axis sensitivity to prenatal stress is evolutionarily ancient and occurs regardless of a species’ overall life history strategy. These efects may therefore be especially important for mediating intra-specifc life-history variation. In addition, these fndings suggest that animal models of prenatal HPA-axis programming may be appropriate for studying similar efects in humans

Unicorn, hare, or tortoise? Using machine learning to predict working memory training performance

People differ considerably in the extent to which they benefit from working memory (WM) training. Although there is increasing research focusing on individual differences associated with WM training outcomes, we still lack an understanding of which specific individual differences, and in what combination, contribute to inter-individual variations in training trajectories. In the current study, 568 undergraduates completed one of several N-back intervention variants over the course of two weeks. Participants\u27 training trajectories were clustered into three distinct training patterns (high performers, intermediate performers, and low performers). We applied machine-learning algorithms to train a binary tree model to predict individuals\u27 training patterns relying on several individual difference variables that have been identified as relevant in previous literature. These individual difference variables included pre-existing cognitive abilities, personality characteristics, motivational factors, video game experience, health status, bilingualism, and socioeconomic status. We found that our classification model showed good predictive power in distinguishing between high performers and relatively lower performers. Furthermore, we found that openness and pre-existing WM capacity to be the two most important factors in distinguishing between high and low performers. However, among low performers, openness and video game background were the most significant predictors of their learning persistence. In conclusion, it is possible to predict individual training performance using participant characteristics before training, which could inform the development of personalized interventions

SIX WEEK CONSISTENCY OF SENSORIMOTOR TEST METHODS

The purpose of this study was to compare sensorimotor testing methods. Therefore 15 healthy and sporty subjects undertook five different sensorimotor tests and repeated the same tests six weeks later without executing any specific sensorimotor training. The main outcome was that movement unspecific and simple tests like the Counter Movement Jump, the maximum isometric force and rate of force development on a blocked leg-press or a single-leg-stance with closed eyes have a better retest-reliability than more specific movements like a balance test on a balance board or a complex movement like a single-legged jump landing. Tests with a specific movement show a learning effect and at complex movements there was almost no correlation, as slight changes in the motion sequence can lead to big differences in the measured scores

Exploring Age-Related Metamemory Differences using Modified Brier Scores and Hierarchical Clustering

Older adults (OAs) typically experience memory failures as they age. However, with some exceptions, studies of OAs’ ability to assess their own memory functions—Metamemory (MM)— find little evidence that this function is susceptible to age-related decline. Our study examines OAs’ and young adults’ (YAs) MM performance and strategy use. Groups of YAs (N = 138) and OAs (N = 79) performed a MM task that required participants to place bets on how likely they were to remember words in a list. Our analytical approach includes hierarchical clustering, and we introduce a new measure of MM—the modified Brier—in order to adjust for differences in scale usage between participants. Our data indicate that OAs and YAs differ in the strategies they use to assess their memory and in how well their MM matches with memory performance. However, there was no evidence that the chosen strategies were associated with differences in MM match, indicating that there are multiple strategies that might be effective (i.e. lead to similar match) in this MM task