1,720,992 research outputs found
Estimating the decomposition of predictive information in multivariate systems
Full text linkIn the study of complex systems from observed multivariate time series, insight into the evolution of one system may be under investigation, which can be explained by the information storage of the system and the information transfer from other interacting systems. We present a framework for the model-free estimation of information storage and information transfer computed as the terms composing the predictive information about the target of a multivariate dynamical process. The approach tackles the curse of dimensionality employing a nonuniform embedding scheme that selects progressively, among the past components of the multivariate process, only those that contribute most, in terms of conditional mutual information, to the present target process. Moreover, it computes all information-theoretic quantities using a nearest-neighbor technique designed to compensate the bias due to the different dimensionality of individual entropy terms. The resulting estimators of prediction entropy, storage entropy, transfer entropy, and partial transfer entropy are tested on simulations of coupled linear stochastic and nonlinear deterministic dynamic processes, demonstrating the superiority of the proposed approach over the traditional estimators based on uniform embedding. The framework is then applied to multivariate physiologic time series, resulting in physiologically well-interpretable information decompositions of cardiovascular and cardiorespiratory interactions during head-up tilt and of joint brain-heart dynamics during sleep
Granger causality analysis of sleep brain-heart interactions
No full textWe studied the networks of Granger causality (GC) between the time series of cardiac vagal autonomic activity and brain wave activities, measured respectively as the normalized high frequency (HF) component of heart rate variability and EEG power in the Î ́, Î ̧, α, Ï , Î2 bands, computed in 10 healthy subjects during sleep. GC analysis was performed by vector autoregressive modeling, and significance of each link in the network was assessed using F-statistics. The whole-night analysis revealed the existence of a fully connected network of brain-heart and brain-brain interactions, with the à EEG power acting as a hub which conveys the largest number of GC links between the heart and brain nodes. These links became progressively more weak when assessed during light sleep, deep sleep, and REM sleep, thus suggesting that brain-heart GC networks are sustained mainly by sleep stage transitions. © 2014 IEEE
Quantifying Time-Variant High-Order Interactions in Brain-Heart Networks during Sleep
No full textThis study introduces an approach, based on the information-theoretic measure of O-information rate, for analyzing time-varying higher order interactions (HOIs) between physiological systems, focusing on brain-heart interactions during sleep. The approach reveals significant modulation of HOIs across sleep stages in brain-heart networks, with reduced redundancy and potential synergistic behavior during REM. Our findings evidence the bidirectional nature of overnight physiological coupling between cardiac and brain rhythms, highlighting the potential for tracking HOIs over time
Investigating Dynamic Brain-Heart Interactions during sleep with Information-Theoretic Measures
No full textThe ongoing exploration of brain-heart interactions in the literature, driven by its significant health implications, remains incomplete despite increasing recent efforts. This study delves into the regularity of electroencephalographic (EEG) oscillations and their synchronization with cardiac vagal longterm variability using Information Storage (IS) and Mutual Information Rate (MIR) measures estimated by linear autoregressive analysis on sleep-time series data. Results reveal significant regularity in slow EEG dynamics, alongside a stronger dynamical coupling with cardiac parasympathetic activity, specifically for high-frequency neural oscillations
Comportements et troubles sexuels induits par l'alcool
No full textSince a long time, alcohol effects on sexual behaviour interest humans. Many myths and beliefs have evolved over centuries. Before the first scientific papers, common literature and theatre highlighted the controversial effects of this beverage on sexual relationships. Recent research reports that small amounts of alcohol do not affect sexual behaviour on the contrary to popular belief of improved sexual performance and arousal. With moderate to large consumption, male and female sexual activities are impaired and characterized by a decreased sensitivity, a loss of sexual desire, and a delayed or absent orgasm and ejaculation. Alcohol is often involved in sexual assaults, but it seems to be more related to a personality disorder with impulsivity rather than a cause by itself. In accordance with the Alcohol Myopia Theory, men under alcoholic influence show a lower control of their sexual desire and impulse as well as a higher misperception of women behaviours. Environmental factors could be also involved in sexual aggression. The sexual risk behaviours are also encouraged by alcohol. However, these data are controversial and include other factors like the individual personality, the socio-cultural influence, or prevention-related programs. Despite a negative association between alcohol and sexual behaviours, studies remain controversial on the alcohol effects. Many methodological limitations are reported such that presently, generalization of the results is hazardous. Many efforts are still required to understand precisely the link between alcohol and sexuality.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Contribution of the study of the dynamic interaction between sleep EEG and heart rate variability
No full textDoctorat en Sciences médicalesinfo:eu-repo/semantics/nonPublishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Predictability decomposition detects the impairment of brain-heart dynamical networks during sleep disorders and their recovery with treatment
Full text linkThis work introduces a framework to study the network formed by the autonomic component of heart rate variability (cardiac process η) and the amplitude of the different electroencephalographic waves (brain processes δ, θ, α, σ, β) during sleep. The framework exploits multivariate linear models to decompose the predictability of any given target process into measures of self-, causal and interaction predictability reflecting respectively the information retained in the process and related to its physiological complexity, the information transferred from the other source processes, and the information modified during the transfer according to redundant or synergistic interaction between the sources. The framework is here applied to the η, δ, θ, α, σ, β time series measured from the sleep recordings of eight severe sleep apnoea-hypopnoea syndrome (SAHS) patients studied before and after long-term treatment with continuous positive airway pressure (CPAP) therapy, and 14 healthy controls. Results show that the full and self-predictability of η, δ and θ decreased significantly in SAHS compared with controls, and were restored with CPAP for δ and θ but not for η. The causal predictability of η and δ occurred through significantly redundant source interaction during healthy sleep, which was lost in SAHS and recovered after CPAP. These results indicate that predictability analysis is a viable tool to assess the modifications of complexity and causality of the cerebral and cardiac processes induced by sleep disorders, and to monitor the restoration of the neuroautonomic control of these processes during long-term treatment
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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