A Novel, Fast, Reliable, and Data-Driven Method for Simultaneous Single-Trial Mining and Amplitude—Latency Estimation Based on Proximity Graphs and Network Analysis

Both amplitude and latency of single-trial EEG/MEG recordings provide valuable information regarding functionality of the human brain. In this article, we provided a data-driven graph and network-based framework for mining information from multi-trial event-related brain recordings. In the first part, we provide the general outline of the proposed methodological approach. In the second part, we provide a more detailed illustration, and present the obtained results on every step of the algorithmic procedure. To justify the proposed framework instead of presenting the analytic data mining and graph-based steps, we address the problem of response variability, a prerequisite to reliable estimates for both the amplitude and latency on specific N/P components linked to the nature of the stimuli. The major question addressed in this study is the selection of representative single-trials with the aim of uncovering a less noisey averaged waveform elicited from the stimuli. This graph and network-based algorithmic procedure increases the signal-to-noise (SNR) of the brain response, a key pre-processing step to reveal significant and reliable amplitude and latency at a specific time after the onset of the stimulus and with the right polarity (N or P). We demonstrated the whole approach using electroencephalography (EEG) auditory mismatch negativity (MMN) recordings from 42 young healthy controls. The method is novel, fast and data-driven succeeding first to reveal the true waveform elicited by MMN on different conditions (frequency, intensity, duration, etc.). The proposed graph-oriented algorithmic pipeline increased the SNR of the characteristic waveforms and the reliability of amplitude and latency within the adopted cohort. We also demonstrated how different EEG reference schemes (REST vs. average) can influence amplitude-latency estimation. Simulation results revealed robust amplitude-latency estimations under different SNR and amplitude-latency variations with the proposed algorithm

Quantitative identification of functional connectivity disturbances in neuropsychiatric lupus based on resting-state fMRI: a robust machine learning approach

Neuropsychiatric systemic lupus erythematosus (NPSLE) is an autoimmune entity comprised of heterogenous syndromes affecting both the peripheral and central nervous system. Research on the pathophysiological substrate of NPSLE manifestations, including functional neuroimaging studies, is extremely limited. The present study examined person-specific patterns of whole-brain functional connectivity in NPSLE patients (n = 44) and age-matched healthy control participants (n = 39). Static functional connectivity graphs were calculated comprised of connection strengths between 90 brain regions. These connections were subsequently filtered through rigorous surrogate analysis, a technique borrowed from physics, novel to neuroimaging. Next, global as well as nodal network metrics were estimated for each individual functional brain network and were input to a robust machine learning algorithm consisting of a random forest feature selection and nested cross-validation strategy. The proposed pipeline is data-driven in its entirety, and several tests were performed in order to ensure model robustness. The best-fitting model utilizing nodal graph metrics for 11 brain regions was associated with 73.5% accuracy (74.5% sensitivity and 73% specificity) in discriminating NPSLE from healthy individuals with adequate statistical power. Closer inspection of graph metric values suggested an increased role within the functional brain network in NSPLE (indicated by higher nodal degree, local efficiency, betweenness centrality, or eigenvalue efficiency) as compared to healthy controls for seven brain regions and a reduced role for four areas. These findings corroborate earlier work regarding hemodynamic disturbances in these brain regions in NPSLE. The validity of the results is further supported by significant associations of certain selected graph metrics with accumulated organ damage incurred by lupus, with visuomotor performance and mental flexibility scores obtained independently from NPSLE patients. View Full-Text Keywords: neuropsychiatric systemic lupus erythematosus; rs-fMRI; graph theory; functional connectivity; surrogate data; machine learning; visuomotor ability; mental flexibilit

New High-Speed a-Si/c-Si- and a-SiC/c-Si-Based Switches

The electrical and optical characteristics of the new high-speed Al/a-Si/c-Si(p)/c-Si(n+)/Al and Al/a- SiC/c-Si(p)/c-Si(n+)/Al optically controlled switches are presented in this paper. These switches exhibit the lowest ever reported values of rise and fall times, for this kind of switches, of about 3ns. They also exhibit a temperature and light reversibly controlled forward breakover voltage (VBF), together with high values of light triggering sensitivity

Morphometric analysis of structural MRI using schizophrenia meta-analytic priors distinguish patients from controls in two independent samples and in a sample of individuals with high polygenic risk

Schizophrenia (SCZ) is associated with structural brain changes, with considerable variation in the extent to which these cortical regions are influenced. We present a novel metric that summarises individual structural variation across the brain, while considering prior effect sizes, established via meta-analysis. We determine individual participant deviation from a within-sample-norm across structural MRI regions of interest (ROIs). For each participant, we weight the normalised deviation of each ROI by the effect size (Cohen’s d) of the difference between SCZ/control for the corresponding ROI from the SCZ Enhancing Neuroimaging Genomics through Meta-Analysis working group. We generate a morphometric risk score (MRS) representing the average of these weighted deviations. We investigate if SCZ-MRS is elevated in a SCZ case/control sample (N(CASE) = 50; N(CONTROL) = 125), a replication sample (N(CASE) = 23; N(CONTROL) = 20) and a sample of asymptomatic young adults with extreme SCZ polygenic risk (N(HIGH-SCZ-PRS) = 95; N(LOW-SCZ-PRS) = 94). SCZ cases had higher SCZ-MRS than healthy controls in both samples (Study 1: β = 0.62, P < 0.001; Study 2: β = 0.81, P = 0.018). The high liability SCZ-PRS group also had a higher SCZ-MRS (Study 3: β = 0.29, P = 0.044). Furthermore, the SCZ-MRS was uniquely associated with SCZ status, but not attention-deficit hyperactivity disorder (ADHD), whereas an ADHD-MRS was linked to ADHD status, but not SCZ. This approach provides a promising solution when considering individual heterogeneity in SCZ-related brain alterations by identifying individual’s patterns of structural brain-wide alterations

Population neuroimaging:generation of a comprehensive data resource within the ALSPAC pregnancy and birth cohort

Neuroimaging offers a valuable insight into human brain development by allowing in vivo assessment of structure, connectivity and function. Multimodal neuroimaging data have been obtained as part of three sub-studies within the Avon Longitudinal Study of Parents and Children, a prospective multigenerational pregnancy and birth cohort based in the United Kingdom. Brain imaging data were acquired when offspring were between 18 and 24 years of age, and included acquisition of structural, functional and magnetization transfer magnetic resonance, diffusion tensor, and magnetoencephalography imaging. This resource provides a unique opportunity to combine neuroimaging data with extensive phenotypic and genotypic measures from participants, their mothers, and fathers

Functional Cardiac Orexin Receptors: Role of Orexin-B/Orexin 2 Receptor in Myocardial Protection.

Orexins/hypocretins exert cardiovascular effects which are centrally mediated. In the present study, we tested whether orexins and their receptors may also act in an autocrine/paracrine manner in the heart exerting direct effects. Quantitative reverse transcription-PCR (RT-PCR), immunohistochemical and Western blot analyses revealed that the rat heart expresses orexins and orexin receptors (OXR). In isolated rat cardiomyocytes, only orexin-B (OR-B) caused an increase in contractile shortening, independent of diastolic or systolic calcium levels. A specific orexin receptor-2 (OX2R) agonist ([Ala11, d-Leu15]-Orexin B) exerted similar effects as OR-B, whereas a specific orexin receptor-1 (OX1R) antagonist (SB-408124) did not alter the responsiveness of OR-B. Treatment of the same model with OR-B resulted in a dose-dependent increase in myosin light chain and troponin-I (TnI) phosphorylation. Following ischaemia/reperfusion in the isolated Langendorff perfused rat heart model, OR-B, but not OR-A, exerts a cardioprotective effect; mirrored in an in vivo model as well. Unlike OR-A, OR-B was also able to induce extracellular signal-regulated kinase (ERK) 1/2 (ERK1/2) and Akt phosphorylation in rat myocardial tissue and ERK1/2 phosphorylation in human heart samples. These findings were further corroborated in an in vivo rat model. In human subjects with heart failure, there is a significant negative correlation between the expression of OX2R and the severity of the disease clinical symptoms, as assessed by the New York Heart Association (NYHA) functional classification. Collectively, we provide evidence of a distinct orexin system in the heart that exerts a cardioprotective role via an OR-B/OX2R pathway.British Heart Foundation and the Heart Research U.K

Reconstruction of the Scalar-Tensor Lagrangian from a LCDM Background and Noether Symmetry

We consider scalar-tensor theories and reconstruct their potential U(\Phi) and coupling F(\Phi) by demanding a background LCDM cosmology. In particular we impose a background cosmic history H(z) provided by the usual flat LCDM parameterization through the radiation (w_{eff}=1/3), matter (w_{eff}=0) and deSitter (w_{eff}=-1) eras. The cosmological dynamical system which is constrained to obey the LCDM cosmic history presents five critical points in each era, one of which corresponding to the standard General Relativity (GR). In the cases that differ from GR, the reconstructed coupling and potential are of the form F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m where m is a constant. This class of scalar tensor theories is also theoretically motivated by a completely independent approach: imposing maximal Noether symmetry on the scalar-tensor Lagrangian. This approach provides independently: i) the form of the coupling and the potential as F(\Phi)\sim \Phi^2 and U(\Phi)\sim F(\Phi)^m, ii) a conserved charge related to the potential and the coupling and iii) allows the derivation of exact solutions by first integrals of motion.Comment: Added comments, discussion, references. 15 revtex pages, 5 fugure