•In health acute stress induces large scale changes at the brain’s network level.•The stress response can be described by the dynamical interactions of three networks.•The salience and default mode ...network are both activated by acute stress.•Stress may as well improve as deteriorate central executive network functioning.•Changes in these three networks account for neuropsychological changes under stress.
The brain's response to stress is a matter of extensive neurocognitive research in an attempt to unravel the mechanistic underpinnings of neural adaptation. In line with the broadly defined concept of acute stress, a wide variety of induction procedures are used to mimic stress experimentally. We set out to review commonalities and diversities of the stress-related functional activity and connectivity changes of functional brain networks in healthy adults across procedures. The acute stress response is consistently associated with both increased activity and connectivity in the salience network (SN) and surprisingly also with increased activity in the default mode network (DMN), while most studies show no changes in the central executive network. These results confirm earlier findings of an essential, coordinating role of the SN in the acute stress response and indicate a dynamic role of the DMN whose function is less clear. Moreover, paradigm specific brain responses have to be taken into account when investigating the role and the within and between network connectivity of these three networks.
A
bstract
We are in an era of precision measurements at the Large Hadron Collider. The precision that can be achieved on some of those is limited however due to large systematic uncertainties. This ...paper introduces a new technique to reduce the total systematic uncertainty by quantifying the systematic impact of single events and correlating it with event observables to identify classes of events that are more sensitive to systematic effects. A proof of concept is presented by means of a simplified top quark mass estimator applied on simulated events. Even without a thorough optimization, it is shown that the total systematic uncertainty can be reduced by at least 30%.
We study fragmentation in electron-positron annihilation assuming a dijet situation, using variables defined independent of any frame. In a collinear situation some of the variables are centered ...around zero with the small deviations attributed to intrinsic transverse momenta and large deviations attributed to additional hard subprocesses. Of course there is a gradual transition. Our modest goal is to show that covariantly defined variables are well suited to get a feeling for the magnitude of intrinsic transverse momenta.
Heterogeneity and comorbidity in psychiatric disorders are common, however, little is known about the impact on well-being and the role of functional limitations. We aimed to identify transdiagnostic ...psychiatric symptom profiles and to study their association with well-being and the mediating role of functional limitations in a naturalistic psychiatric patient group.
We used four disorder-specific questionnaires to assess symptom severity within a sample of 448 psychiatric patients with stress-related and/or neurodevelopmental disorders and 101 healthy controls. Using both exploratory and confirmatory factor analyses we identified transdiagnostic symptom profiles, which we entered into a linear regression analysis to assess their association with well-being and the mediating role of functional limitations in this association.
We identified eight transdiagnostic symptom profiles, covering mood, self-image, anxiety, agitation, empathy, non-social interest, hyperactivity and cognitive focus. Mood and self-image showed the strongest association with well-being in both patients and controls, while self-image also showed the highest transdiagnostic value. Functional limitations were significantly associated with well-being and fully mediated the relationship between cognitive focus and well-being.
The participant sample consisted of a naturalistic group of out-patients. While this strengthens the ecological validity and transdiagnostic perspective of this study, the patients with a single neurodevelopmental disorder were underrepresented.
Transdiagnostic symptom profiles are valuable in understanding what reduces well-being in psychiatric populations, thereby opening new avenues for functionally meaningful interventions.
•We found eight transdiagnostic symptom profiles.•Mood and Self-Image had most impact on well-being.•Cognitive Focus is only indirectly associated with well-being.•The impact of symptom profile on functioning and well-being is transdiagnostic.•Transdiagnostic psychiatric symptom profiles may be valuable for treatment options.
Introduction
Electroconvulsive therapy (ECT) is proposed to exert an effect on white matter (WM) microstructure, but the limited power of previous studies made it difficult to highlight consistent ...patterns of change in diffusion metrics.
Objectives
We initiated a multi-site mega-analysis and sought to address whether changes in WM microstructure occur following ECT.
Methods
To this end, diffusion tensor imaging (DTI) data (n=58) from 4 different sites were harmonized before pooling them by using ComBat, a batch-effect correction tool that removes inter-site technical variability, preserves inter-site biological variability and maximizes statistical power. Downstream statistical analyses aimed to quantify changes in Fractional anisotropy (FA), Mean Diffusivity (MD), Radial Diffusivity (RD) and Axial Diffusivity (AD), by employing whole-brain, tract-based spatial statistics (TBSS).
Results
ECT increases FA in the right splenium of the corpus callosum and the left cortico-spinal tract. Both the left superior longitudinal fasciculus and the right inferior fronto-occipital fasciculus showed increases in AD. Increases in MD and RD could be observed in overlapping white matter structures of both hemispheres. Finally, responders showed significantly smaller FA values in the left forceps major and smaller AD values in the right uncinate fasciculus compared with non-responders.
Conclusions
This is the first and largest multi-site mega-analysis to demonstrate that ECT normalizes altered WM microstructure in important brain circuits that are implicated in the pathophysiology of depression. Furthermore, responders appear to present a more decreased WM integrity at baseline, which if replicated could serve as a biomarker for ECT response.
Disclosure
No significant relationships.
Electroconvulsive therapy (ECT) is an effective treatment for severe depression and induces gray matter (GM) increases in the brain. Small-scale studies suggest that ECT also leads to changes in ...brain functioning, but findings are inconsistent. In this study, we investigated the influence of ECT on changes in both brain structure and function and their relation to clinical improvement using multicenter neuroimaging data from the Global ECT-MRI Research Collaboration (GEMRIC).
We analyzed T1-weighted structural magnetic resonance imaging (MRI) and functional resting-state MRI data of 88 individuals (49 male) with depressive episodes before and within one week after ECT. We performed voxel-based morphometry on the structural data and calculated fractional amplitudes of low-frequency fluctuations, regional homogeneity, degree centrality, functional connectomics, and hippocampus connectivity for the functional data in both unimodal and multimodal analyses. Longitudinal effects in the ECT group were compared to repeated measures of healthy controls (n = 27).
Wide-spread increases in GM volume were found in patients following ECT. In contrast, no changes in any of the functional measures were observed, and there were no significant differences in structural or functional changes between ECT responders and non-responders. Multimodal analysis revealed that volume increases in the striatum, supplementary motor area and fusiform gyrus were associated with local changes in brain function.
These results confirm wide-spread increases in GM volume, but suggest that this is not accompanied by functional changes or associated with clinical response. Instead, focal changes in brain function appear related to individual differences in brain volume increases.
•Electroconvulsive therapy induces brain-wide gray matter increases.•Electroconvulsive therapy does not induce a global change in brain function.•Focal changes in brain function are related to individual volume increase changes.
Electroconvulsive therapy (ECT) is the most effective treatment for patients suffering from severe or treatment-resistant major depressive disorder (MDD). Unfortunately its underlying neurobiological ...mechanisms are still unclear. One line of evidence indicates that the seizures produced by ECT induce or stimulate neuroplasticity effects. Although these seizures also affect the cortex, the effect of ECT on cortical thickness is not investigated until now. We acquired structural magnetic resonance imaging data in 19 treatment-resistant MDD patients before and after a bilateral ECT course, and 16 healthy controls at 2 time points, and compared changes in cortical thickness between the groups. Our results reveal that ECT induces significant, bilateral increases in cortical thickness, including the temporal pole, inferior and middle temporal cortex and the insula. The pattern of increased cortical thickness was predominant in regions that are associated with seizure onset in ECT. Post hoc analyses showed that the increase in thickness of the insular cortex was larger in responders than in non-responders, which may point to a specific relationship of this region with treatment effects of ECT.
Introduction
ECT is an effective treatment for depression. Beyond its therapeutic effect on mood it has a unique impact on psychomotor and cognitive symptoms.Its mechanism of action remains still ...unclear. To investigate this, we set out to study the brain’s response to ECT from a large-scale brain-network perspective.
Objectives
The aim of this study was to investigate changes in resting-state functional connectivity following ECT at the whole brain, between-network and within-network level, in patients with a depressive episode.
Methods
Resting-state FMRI data were collected from 17 patients with depression before and after an ECT course. Using a group independent component analysis approach, we focused on four networks that are known to be affected in depression: the salience network (SN), default mode network (DMN), cognitive executive network (CEN) and a subcortical network (SCN). Clinical measures including mood, cognition and psychomotor symptoms were assessed.
Results
ECT increased connectivity of the left CEN with the left angular gyrus and left middle frontal gyrus. An increase in left CEN within network connectivity was observed. Both the right CEN and the SCN showed increased connectivity with the precuneus. Furthermore, the anterior DMN showed increased connectivity with the left amygdala. Finally, improvement of psychomotor retardation was positively correlated with an increase of within-posterior DMN connectivity.
Conclusions
We demonstrate that ECT induces a significant increase of connectivity at both the whole brain and within-network level. Furthermore, we provide first evidence on the association between an increase of within posterior DMN connectivity and an improvement of psychomotor retardation, a core symptom of depression.
Disclosure
No significant relationships.
The SoLid experiment, short for Search for Oscillations with a Lithium-6 detector, is a new generation neutrino experiment which tries to address the key challenges for high precision reactor ...neutrino measurements at very short distances from a reactor core and with little or no overburden. The primary goal of the SoLid experiment is to perform a precise measurement of the electron antineutrino energy spectrum and flux and to search for very short distance neutrino oscillations as a probe of eV-scale sterile neutrinos. This paper describes the SoLid detection principle, the mechanical design and the construction of the detector. It then reports on the installation and commissioning on site near the BR2 reactor, Belgium, and finally highlights its performance in terms of detector response and calibration.
The next generation of very-short-baseline reactor experiments will require compact detectors operating at surface level and close to a nuclear reactor. This paper presents a new detector concept ...based on a composite solid scintillator technology. The detector target uses cubes of polyvinyltoluene interleaved with 6LiF:ZnS(Ag) phosphor screens to detect the products of the inverse beta decay reaction. A multi-tonne detector system built from these individual cells can provide precise localisation of scintillation signals, making efficient use of the detector volume. Monte Carlo simulations indicate that a neutron capture efficiency of over 70 % is achievable with a sufficient number of 6LiF:ZnS(Ag) screens per cube and that an appropriate segmentation enables a measurement of the positron energy which is not limited by γ-ray leakage. First measurements of a single cell indicate that a very good neutron-gamma discrimination and high neutron detection efficiency can be obtained with adequate triggering techniques. The light yield from positron signals has been measured, showing that an energy resolution of 14%/√E(MeV) is achievable with high uniformity. A preliminary neutrino signal analysis has been developed, using selection criteria for pulse shape, energy, time structure and energy spatial distribution and showing that an antineutrino efficiency of 40% can be achieved. It also shows that the fine segmentation of the detector can be used to significantly decrease both correlated and accidental backgrounds.
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