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Unraveling cardiac arrhythmia frequency: comparative analysis using time and frequency domain algorithms
No full textDuring cardiac arrhythmia, the heart frequency is an important physiological parameter that can be identified by analyzing electrocardiogram (ECG) signals. However, the accuracy of the frequency estimation becomes increasingly challenging as the ECG morphology becomes more complex, for example, during transitions from tachycardia to fibrillation. In this paper, the authors compare seven conventional and novel time- and frequency-domain methods for cardiac arrhythmia frequency analysis, including an algorithm used in implantable cardioverter defibrillators. The objective of this study is to identify the approaches that reveal the potential presence of a dominant frequency and its role in characterizing different arrhythmia types. By evaluating the strengths and weaknesses of each method, the authors aim to establish an informative framework for extracting meaningful insights from electrocardiogram data in the context of cardiac arrhythmia frequency. In order to ascertain the statistical relevance of the methods, a dataset comprising 112 ECGs from arrhythmic murine hearts was analyzed. Additionally, a dataset comprising human arrhythmia data was examined to validate the techniques presented. The R-library, which contains the frequency determination algorithms, as well as the murine data set, is made available to the reader for the purposes of further testing and supplementation
Cr-induced phase instability and hierarchical microstructure development in Co-based superalloys
No full textLinguistic information compensates for age-related decline in attentional filtering
No full textAs we age, understanding speech in social situations imposes an increasingly difficult challenge to the auditory system. However, the attentional mechanisms underlying age-related speech comprehension difficulties in multitalker situations remain unclear. We collected EEG signals while 63 normal hearing participants from 19 to 71 years performed a speech comprehension task involving a multitalker paradigm at individually adjusted target-to-distractor ratios. Combining trial-resolved multivariate temporal response function modeling with detailed behavioral comprehension responses, we provide a window into lower-level impairments and higher-level compensatory mechanisms across the adult life span. Neuro-behavioral correlations on a trial-by-trial level provide direct evidence for increased distractor representation underlying reduced behavioral performance in late adulthood. This points towards increased distractability as a potential mechanism underlying age-related speech comprehension deficits. Additionally, at the behavioral and neural levels, we show that older adults relied more on higher-level linguistic information. Finally, we show that an increased reliance on linguistic information may serve as a compensatory mechanism that supports comprehension performance across the adult life span. Summarizing, combining behavioral and neural data, we directly show that an increased reliance on linguistic processing can offset age-related impairments in attentional filtering
Noradrenergic circuit adaptations underlying predatory aggression
No full textBehaviors are adaptive traits shaped by natural selection. Nevertheless, the genetic, molecular, and neural modifications that underlie behavioral innovations remain poorly understood. Here, I identify specialized adaptations linked to the evolution of invertebrate aggression by leveraging a comparative nematode framework, Pristionchus pacificus versus Caenorhabditis elegans, to dissect the evolution of predatory aggression and its interface with territoriality and feeding. We combined high throughput tracking with a semi-supervised behavioral state labeling pipeline, cell type resolved perturbations, receptor mapping, and targeted CRISPR screens. Quantitative analyses revealed that octopamine and tyramine function as an antagonistic pair at the molecular level: tbh-1 loss (↓octopamine) reduced entry into the predatory state, tdc-1 loss (↓tyramine and ↓octopamine) rescued this effect. Furthermore, exogenous octopamine and tyramine also shifted state occupancy in opposite directions. Behavioral assays of CRISPR mutants showed that mutations in the octopamine receptors ser-3/ser-6 phenocopied tbh-1 deficits, whereas mutations in the tyramine associated ion channel, lgc-55 mirrored the rescue observed in tdc-1. Crucially, we found that while the neurotransmitter source remained conserved across species, the receptor expression has been rewired with differential expression observed across head sensory neurons. Notably, P. pacificus specific SER-3 expression is detected in IL2 sensory neurons and functional silencing of these reduces predatory search, biting, and feeding. This establishes the IL2 neurons as a sensory hub for prey detection and state gating. Comparative tests across another basal Diplogastrid species indicate that octopamine's pro-aggressive role is conserved within this family. Thus adaptations in noradrenergic circuits emerges as a central mechanism for shaping the evolution of aggressive behavioral states in nematodes
