Task-Related modulations of BOLD low-frequency fluctuations within the default mode Network

Spontaneous low-frequency Blood-Oxygenation Level-Dependent (BOLD) signals acquired during resting state are characterized by spatial patterns of synchronous fluctuations, ultimately leading to the identification of robust brain networks. The resting-state brain networks, including the Default Mode Network (DMN), are demonstrated to persist during sustained task execution, but the exact features of task-related changes of network properties are still not well characterized. In this work we sought to examine in a group of 20 healthy volunteers (age 33 ± 6 years, 8 F/12 M) the relationship between changes of spectral and spatiotemporal features of one prominent resting-state network, namely the DMN, during the continuous execution of a working memory n-back task. We found that task execution impacted on both functional connectivity and amplitude of BOLD fluctuations within large parts of the DMN, but these changes correlated between each other only in a small area of the posterior cingulate. We conclude that combined analysis of multiple parameters related to connectivity, and their changes during the transition from resting state to continuous task execution, can contribute to a better understanding of how brain networks rearrange themselves in response to a task

Scale-invariant rearrangement of resting state networks in the human brain under sustained stimulation

Brain activity at rest is characterized by widely distributed and spatially specific patterns of synchronized low-frequency blood-oxygenation level-dependent (BOLD) fluctuations, which correspond to physiologically relevant brain networks. This network behaviour is known to persist also during task execution, yet the details underlying task-associated modulations of within- and between-network connectivity are largely unknown. In this study we exploited a multi-parametric and multi-scale approach to investigate how low-frequency fluctuations adapt to a sustained n-back working memory task. We found that the transition from the resting state to the task state involves a behaviourally relevant and scale-invariant modulation of synchronization patterns within both task-positive and default mode networks. Specifically, decreases of connectivity within networks are accompanied by increases of connectivity between networks. In spite of large and widespread changes of connectivity strength, the overall topology of brain networks is remarkably preserved. We show that these findings are strongly influenced by connectivity at rest, suggesting that the absolute change of connectivity (i.e., disregarding the baseline) may not be the most suitable metric to study dynamic modulations of functional connectivity. Our results indicate that a task can evoke scale-invariant, distributed changes of BOLD fluctuations, further confirming that low frequency BOLD oscillations show a specialized response and are tightly bound to task-evoked activation

Evaluation of denoising strategies for task-based functional connectivity: Equalizing residual motion artifacts between rest and cognitively demanding tasks

In-scanner head motion represents a major confounding factor in functional connectivity studies and it raises particular concerns when motion correlates with the effect of interest. One such instance regards research focused on functional connectivity modulations induced by sustained cognitively demanding tasks. Indeed, cognitive engagement is generally associated with substantially lower in-scanner movement compared with unconstrained, or minimally constrained, conditions. Consequently, the reliability of condition-dependent changes in functional connectivity relies on effective denoising strategies. In this study, we evaluated the ability of common denoising pipelines to minimize and balance residual motion-related artifacts between resting-state and task conditions. Denoising pipelines—including realignment/tissue-based regression, PCA/ICA-based methods (aCompCor and ICA-AROMA, respectively), global signal regression, and censoring of motion-contaminated volumes—were evaluated according to a set of benchmarks designed to assess either residual artifacts or network identifiability. We found a marked heterogeneity in pipeline performance, with many approaches showing a differential efficacy between rest and task conditions. The most effective approaches included aCompCor, optimized to increase the noise prediction power of the extracted confounding signals, and global signal regression, although both strategies performed poorly in mitigating the spurious distance-dependent association between motion and connectivity. Censoring was the only approach that substantially reduced distance-dependent artifacts, yet this came at the great cost of reduced network identifiability. The implications of these findings for best practice in denoising task-based functional connectivity data, and more generally for resting-state data, are discussed

Implementing an evidence-based computerized decision support system linked to electronic health records to improve care for cancer patients: the ONCO-CODES study protocol for a randomized controlled trial.

BACKGROUND: Computerized decision support systems (CDSSs) are computer programs that provide doctors with person-specific, actionable recommendations, or management options that are intelligently filtered or presented at appropriate times to enhance health care. CDSSs might be integrated with patient electronic health records (EHRs) and evidence-based knowledge. METHODS/DESIGN: The Computerized DEcision Support in ONCOlogy (ONCO-CODES) trial is a pragmatic, parallel group, randomized controlled study with 1:1 allocation ratio. The trial is designed to evaluate the effectiveness on clinical practice and quality of care of a multi-specialty collection of patient-specific reminders generated by a CDSS in the IRCCS Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) hospital. We hypothesize that the intervention can increase clinician adherence to guidelines and, eventually, improve the quality of care offered to cancer patients. The primary outcome is the rate at which the issues reported by the reminders are resolved, aggregating specialty and primary care reminders. We will include all the patients admitted to hospital services. All analyses will follow the intention-to-treat principle. DISCUSSION: The results of our study will contribute to the current understanding of the effectiveness of CDSSs in cancer hospitals, thereby informing healthcare policy about the potential role of CDSS use. Furthermore, the study will inform whether CDSS may facilitate the integration of primary care in cancer settings, known to be usually limited. The increasing use of and familiarity with advanced technology among new generations of physicians may support integrated approaches to be tested in pragmatic studies determining the optimal interface between primary and oncology care. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02645357

Risk of Colorectal Cancer in Inflammatory Bowel Disease: Prevention and Monitoring Strategies According With Risk Factors

Colorectal cancer (CRC) is slightly increased in inflammatory bowel disease (IBD) patients, with roughly a 2.5-fold increase compared to the general population. Clinical features associated to CRC risks are extent and severity of colonic involvement, disease duration, concomitant primary sclerosing cholangitis (PSC) and/or familial history of CRC in first-degree relatives. Colonic Crohn’s disease (CD) and ulcerative colitis (UC) share similar risks when similar colonic extent is affected. Risk stratification affects outcomes and surveillance programs.Newer endoscopic techniques substantially ameliorated diagnostic performance of endoscopy, and nowadays the standard for CRC surveillance in IBD patients is high-definition endoscopy, with dye-spray or virtual colonoscopy, oriented at targeted (+ random) colonic biopsies.Visible dysplastic lesions should be considered for endoscopic resection, while invisible dysplasia is still a mandatory proctocolectomy indication.Newer endoscopic interventional techniques (endoscopic mucosa resection, EMR, and endoscopic submucosal dissection, ESD) are appropriate therapeutic techniques to be delivered, but long-term risks of cancer should be balanced towards proctocolectomy

Brain Network Modularity During a Sustained Working-Memory Task

International audienceSpontaneous oscillations of the blood oxygenation level-dependent (BOLD) signal are spatially synchronized within specific brain networks and are thought to reflect synchronized brain activity. Networks are modulated by the performance of a task, even if the exact features and degree of such modulations are still elusive. The presence of networks showing anticorrelated fluctuations lend initially to suppose that a competitive relationship between the default mode network (DMN) and task positive networks (TPNs) supports the efficiency of brain processing. However, more recent results indicate that cooperative and competitive dynamics between networks coexist during task performance. In this study, we used graph analysis to assess the functional relevance of the topological reorganization of brain networks ensuing the execution of a steady state working-memory (WM) task. Our results indicate that the performance of an auditory WM task is associated with a switching between different topological configurations of several regions of specific networks, including frontoparietal, ventral attention, and dorsal attention areas, suggesting segregation of ventral attention regions in the presence of increased overall integration. However, the correct execution of the task requires integration between components belonging to all the involved networks.</div

Nonalcoholic Fatty Liver Disease in Inflammatory Bowel Disease: Prevalence and Risk Factors

Background: Nonalcoholic fatty liver disease (NAFLD) is common in inflammatory bowel diseases (IBD). Herein, NAFLD prevalence and risk factors in a large IBD cohort were evaluated and compared to that of a non-IBD sample. Methods: Crohn’s disease/ulcerative colitis outpatients referred to IBD service of our Gastroenterology Unit were enrolled. Subjects affected by functional and motor gastrointestinal disorders, in whom IBD was ruled out, referred to general outpatient service in the same area, were considered as nonIBD group. Exclusion criteria were based on previous diagnosis of nonNAFLD chronic liver diseases and secondary causes of fat liver overload. Characteristics of IBD and liver status were collected. Risk factors for metabolic syndrome were analyzed. Ultrasonographic presence and degree of steatosis were assessed. Data were examined by univariate and multivariate analyses. Results: For this study 465 IBD and 189 non-IBD subjects were consecutively enrolled. NAFLD was found in 28.0% and 20.1% in IBD and non-IBD subjects, respectively (P = 0.04). IBD patients with NAFLD were younger than non-IBD ones. There was no significant difference in steatosis grade and association between NAFLD and IBD behavior, extension, activity, and drugs. In the IBD group, multivariate analysis demonstrated that NAFLD was independently associated to metabolic syndrome (OR=2.24, 95%CI 1.77–28.81), diabetes (OR=1.71, 95%CI 1.43–12.25), fasting blood glucose (OR=1.36, 95%CI 1.13–1.68), and abdominal circumference (OR=1.68, 95%CI 1.15–14.52). Conclusions: NAFLD is more common and occurs at a younger age in IBD than in nonIBD subjects. However, further investigation is required to ascertain possible NAFLD pathogenic IBD-related factors other than conventional/metabolic ones