Epileptic seizures as condensed sleep: an analysis of network dynamics from electroencephalogram signals

Both deepening sleep and evolving epileptic seizures are associated with increasing slow-wave activity. Larger-scale functional networks derived from electroencephalogram indicate that in both transitions dramatic changes of communication between brain areas occur. During seizures these changes seem to be 'condensed', because they evolve more rapidly than during deepening sleep. Here we set out to assess quantitatively functional network dynamics derived from electroencephalogram signals during seizures and normal sleep. Functional networks were derived from electroencephalogram signals from wakefulness, light and deep sleep of 12 volunteers, and from pre-seizure, seizure and post-seizure time periods of 10 patients suffering from focal onset pharmaco-resistant epilepsy. Nodes of the functional network represented electrical signals recorded by single electrodes and were linked if there was non-random cross-correlation between the two corresponding electroencephalogram signals. Network dynamics were then characterized by the evolution of global efficiency, which measures ease of information transmission. Global efficiency was compared with relative delta power. Global efficiency significantly decreased both between light and deep sleep, and between pre-seizure, seizure and post-seizure time periods. The decrease of global efficiency was due to a loss of functional links. While global efficiency decreased significantly, relative delta power increased except between the time periods wakefulness and light sleep, and pre-seizure and seizure. Our results demonstrate that both epileptic seizures and deepening sleep are characterized by dramatic fragmentation of larger-scale functional networks, and further support the similarities between sleep and seizures.

Sympathy, distress, and prosocial behavior of preschool children in four cultures

This study examined emotional responding (sympathy and distress) and prosocial behavior as well as their relations across four cultures in a specific context. Preschool children (N = 212) from two Western cultures, Germany and Israel, and two South-East Asian cultures, Indonesia and Malaysia, participated in this study. Children's emotional reactions and prosocial behavior were observed when interacting with an adult in a quasi-experimental situation. Results showed that children from the two South-East Asian cultures, as compared to children from the two Western cultures, displayed more self-focused distress and less prosocial behavior. Across cultures, a positive relation between sympathy and prosocial behavior and a negative relation between self-focused distress and prosocial behavior were found. The strengths of these relations were moderated by culture. These results are discussed with regard to their cultural meaning in the specific experimental situation as well as to general culture-specific characteristics.

Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

It is commonly assumed that natural selection imposed by predators is the prevailing force driving the evolution of aposematic traits. Here, we demonstrate that aposematic signals are shaped by sexual selection as well. We evaluated sexual selection for coloration brightness in populations of the poison frog Oophaga [Dendrobates] pumilio in Panama's Bocas del Toro archipelago. We assessed female preferences for brighter males by manipulating the perceived brightness of spectrally matched males in two-way choice experiments. We found strong female preferences for bright males in two island populations and weaker or ambiguous preferences in females from mainland populations. Spectral reflectance measurements, coupled with an O. pumilio-specific visual processing model, showed that O. pumilio coloration was significantly brighter in island than in mainland morphs. In one of the island populations (Isla Solarte), males were significantly more brightly colored than females. Taken together, these results provide evidence for directional sexual selection on aposematic coloration and document sexual dimorphism in vertebrate warning coloration. Although aposematic signals have long been upheld as exemplars of natural selection, our results show that sexual selection should not be ignored in studies of aposematic evolution.

Higher emotional distress in female partners of cancer patients: prevalence and patient-partner interdependencies in a 3-year cohort

OBJECTIVE: Assessment and treatment of psychological distress in cancer patients was recognized as a major challenge. The role of spouses, caregivers, and significant others became of salient importance not only because of their supportive functions but also in respect to their own burden. The purpose of this study was to assess the amount of distress in a mixed sample of cancer patients and their partners and to explore the dyadic interdependence. METHODS: An initial sample of 154 dyads was recruited, and distress questionnaires (Hospital Anxiety and Depression Scale, Symptom Checklist 9-Item Short Version and 12-Item Short Form Health Survey) were assessed over four time points. Linear mixed models and actor-partner interdependence models were applied. RESULTS: A significant proportion of patients and their partners (up to 40%) reported high levels of anxiety, depression, psychological distress, and low quality of life over the course of the investigation. Mixed model analyses revealed that higher risks for clinical relevant anxiety and depression in couples exist for female patients and especially for female partners. Although psychological strain decreased over time, the risk for elevated distress in female partners remained. Modeling patient-partner interdependence over time stratified by patients' gender revealed specific effects: a moderate correlation between distress in patients and partners, and a transmission of distress from male patients to their female partners. CONCLUSIONS: Our findings provide empirical support for gender-specific transmission of distress in dyads coping with cancer. This should be considered as an important starting point for planning systemic psycho-oncological interventions and conceptualizing further research.

Vulnerability Following a Critical Life Event: Temporary Crisis or Chronic Distress? A Psychological Controversy, Methodological Considerations, and Empirical Evidence

This contribution deals with psychological vulnerability resulting from marital breakup after a long-term relationship. Despite the existing vast body of consolidated knowledge on divorce and psychological adaptation, there are still several controversies concerning the vulnerabilizing impact of marital breakup. One major issue refers to the question of whether vulnerability after marital breakup is a temporary crisis or rather a chronic strain. In this chapter we want to present two possible methodological options to tackle this question: First, comparing a sample of almost 1000 middle-aged persons, who were married on average 19 years, and who experienced a marital split within the last 5 years (4 time groups), with a group of age-matched married controls with regard to various indicators of psychological vulnerability (such as depression and hopelessness). Second, comparing within the divorced group the most vulnerable individuals (in terms of depression, hopelessness, life satisfaction) with those who were the least affected, regarding intra-personal resources (personality, resilience), divorce circumstances, post-divorce situation, and socio-economic resources. The study results underline the vulnerabilizing impact of marital breakup, but at the same time they reveal individual differences in psychological adaptation especially due to personality, new partnership, economic resources, and last but not least due to time. Furthermore our data strongly suggest that there is not a generalized psychological vulnerability after marital breakup, but that the emotional dimensions such as depression or feelings of not overcoming the loss are more affected than the more cognitive ones such as life satisfaction.

A patient-reported outcome measure to identify occurrence and distress of post-surgery symptoms of WOMen with vulvAr Neoplasia (WOMAN-PRO) - a cross sectional study.

OBJECTIVE The aim of the study was to describe the (a) symptom experience of women with vulvar intraepithelial neoplasia and vulvar cancer (vulvar neoplasia) during the first week after hospital discharge, and (b) associations between age, type of disease, stage of disease, the extent of surgical treatment and symptom experience. METHODS This cross-sectional study was conducted in eight hospitals in Germany and Switzerland (Clinical Trial ID: NCT01300663). Symptom experience after surgical treatment in women with vulvar neoplasia was measured with our newly developed WOMAN-PRO instrument. Outpatients (n=65) rated 31 items. We used descriptive statistics and regression analysis. RESULTS The average number of symptoms reported per patient was 20.2 (SD 5.77) with a range of 5 to 31 symptoms. The three most prevalent wound-related symptoms were 'swelling' (n=56), 'drainage' (n=54) and 'pain' (n=52). The three most prevalent difficulties in daily life were 'sitting' (n=63), 'wearing clothes' (n=56) and 'carrying out my daily activities' (n=51). 'Tiredness' (n=62), 'insecurity' (n=54) and 'feeling that my body has changed' (n=50) were the three most prevalent psychosocial symptoms/issues. The most distressing symptoms were 'sitting' (Mean 2.03, SD 0.88), 'open spot (e.g. opening of skin or suture)' (Mean 1.91, SD 0.93), and 'carrying out my daily activities' (Mean 1.86, SD 0.87), which were on average reported as 'quite a bit' distressing. Negative associations were found between psychosocial symptom experience and age. CONCLUSIONS WOMAN-PRO data showed a high symptom prevalence and distress, call for a comprehensive symptom assessment, and may allow identification of relevant areas in symptom management.

The role of learning-related dopamine signals in addiction vulnerability

Dopaminergic signals play a mathematically precise role in reward-related learning, and variations in dopaminergic signaling have been implicated in vulnerability to addiction. Here, we provide a detailed overview of the relationship between theoretical, mathematical, and experimental accounts of phasic dopamine signaling, with implications for the role of learning-related dopamine signaling in addiction and related disorders. We describe the theoretical and behavioral characteristics of model-free learning based on errors in the prediction of reward, including step-by-step explanations of the underlying equations. We then use recent insights from an animal model that highlights individual variation in learning during a Pavlovian conditioning paradigm to describe overlapping aspects of incentive salience attribution and model-free learning. We argue that this provides a computationally coherent account of some features of addiction.

Distortion-free enhancement of terahertz signals measured by electro-optic sampling. I. Theory

We present three methods for the distortion-free enhancement of THz signals measured by electro-optic sampling in zinc blende-type detector crystals, e.g., ZnTe or GaP. A technique commonly used in optically heterodyne-detected optical Kerr effect spectroscopy is introduced, which is based on two measurements at opposite optical biases near the zero transmission point in a crossed polarizer detection geometry. In contrast to other techniques for an undistorted THz signal enhancement, it also works in a balanced detection scheme and does not require an elaborate procedure for the reconstruction of the true signal as the two measured waveforms are simply subtracted to remove distortions. We study three different approaches for setting an optical bias using the Jones matrix formalism and discuss them also in the framework of optical heterodyne detection. We show that there is an optimal bias point in realistic situations where a small fraction of the probe light is scattered by optical components. The experimental demonstration will be given in the second part of this two-paper series [J. Opt. Soc. Am. B, doc. ID 204877 (2014, posted online)].

Distortion-free enhancement of terahertz signals measured by electro-optic sampling. II. Experiment

Three methods for distortion-free enhancement of electro-optic sampling measurements of terahertz signals are tested. In the first part of this two-paper series [J. Opt. Soc. Am B 31, 904–910 (2014)], the theoretical framework for describing the signal enhancement was presented and discussed. As the applied optical bias is decreased, individual signal traces become enhanced but distorted. Here we experimentally show that nonlinear signal components that distort the terahertz electric field measurement can be removed by subtracting traces recorded with opposite optical bias values. In all three methods tested, we observe up to an order of magnitude increase in distortion-free signal enhancement, in agreement with the theory, making possible measurements of small terahertz-induced transient birefringence signals with increased signal-to-noise ratio.

Influence of inspiration to expiration ratio on cyclic recruitment and derecruitment of atelectasis in a saline lavage model of acute respiratory distress syndrome*

OBJECTIVE Cyclic recruitment and derecruitment of atelectasis can occur during mechanical ventilation, especially in injured lungs. Experimentally, cyclic recruitment and derecruitment can be quantified by respiration-dependent changes in PaO2 (ΔPaO2), reflecting the varying intrapulmonary shunt fraction within the respiratory cycle. This study investigated the effect of inspiration to expiration ratio upon ΔPaO2 and Horowitz index. DESIGN Prospective randomized study. SETTING Laboratory investigation. SUBJECTS Piglets, average weight 30 ± 2 kg. INTERVENTIONS At respiratory rate 6 breaths/min, end-inspiratory pressure (Pendinsp) 40 cm H2O, positive end-expiratory pressure 5 cm H2O, and FIO2 1.0, measurements were performed at randomly set inspiration to expiration ratios during baseline healthy and mild surfactant depletion injury. Lung damage was titrated by repetitive surfactant washout to induce maximal cyclic recruitment and derecruitment as measured by multifrequency phase fluorimetry. Regional ventilation distribution was evaluated by electrical impedance tomography. Step changes in airway pressure from 5 to 40 cm H2O and vice versa were performed after lavage to calculate PO2-based recruitment and derecruitment time constants (TAU). MEASUREMENTS AND MAIN RESULTS In baseline healthy, cyclic recruitment and derecruitment could not be provoked, whereas in model acute respiratory distress syndrome, the highest ΔPaO2 were routinely detected at an inspiration to expiration ratio of 1:4 (range, 52-277 torr [6.9-36.9 kPa]). Shorter expiration time reduced cyclic recruitment and derecruitment significantly (158 ± 85 torr [21.1 ± 11.3 kPa] [inspiration to expiration ratio, 1:4]; 25 ± 12 torr [3.3 ± 1.6 kPa] [inspiration to expiration ratio, 4:1]; p < 0.0001), whereas the PaO2/FIO2 ratio increased (267 ± 50 [inspiration to expiration ratio, 1:4]; 424 ± 53 [inspiration to expiration ratio, 4:1]; p < 0.0001). Correspondingly, regional ventilation redistributed toward dependent lung regions (p < 0.0001). Recruitment was much faster (TAU: fast 1.6 s [78%]; slow 9.2 s) than derecruitment (TAU: fast 3.1 s [87%]; slow 17.7 s) (p = 0.0078). CONCLUSIONS Inverse ratio ventilation minimizes cyclic recruitment and derecruitment of atelectasis in an experimental model of surfactant-depleted pigs. Time constants for recruitment and derecruitment, and regional ventilation distribution, reflect these findings and highlight the time dependency of cyclic recruitment and derecruitment.

Defensive weapons and defense signals in plants: Some metabolites serve both roles

The defense of plants against herbivores and pathogens involves the participation of an enormous range of different metabolites, some of which act directly as defensive weapons against enemies (toxins or deterrents) and some of which act as components of the complex internal signaling network that insures that defense is timed to enemy attack. Recent work reveals a surprising trend: The same compounds may act as both weapons and signals of defense. For example, two groups of well-studied defensive weapons, glucosinolates and benzoxazinoids, trigger the accumulation of the protective polysaccharide callose as a barrier against aphids and pathogens. In the other direction, several hormones acting in defense signaling (and their precursors and products) exhibit activity as weapons against pathogens. Knowing which compounds are defensive weapons, which are defensive signals and which are both is vital for understanding the functioning of plant defense systems.

General distress, hopelessness—suicidal ideation and worrying in adolescence: Concurrent and predictive validity of a symptom-level bifactor model for clinical diagnoses

BACKGROUND: Clinical disorders often share common symptoms and aetiological factors. Bifactor models acknowledge the role of an underlying general distress component and more specific sub-domains of psychopathology which specify the unique components of disorders over and above a general factor. METHODS: A bifactor model jointly calibrated data on subjective distress from The Mood and Feelings Questionnaire and the Revised Children's Manifest Anxiety Scale. The bifactor model encompassed a general distress factor, and specific factors for (a) hopelessness-suicidal ideation, (b) generalised worrying and (c) restlessness-fatigue at age 14 which were related to lifetime clinical diagnoses established by interviews at ages 14 (concurrent validity) and current diagnoses at 17 years (predictive validity) in a British population sample of 1159 adolescents. RESULTS: Diagnostic interviews confirmed the validity of a symptom-level bifactor model. The underlying general distress factor was a powerful but non-specific predictor of affective, anxiety and behaviour disorders. The specific factors for hopelessness-suicidal ideation and generalised worrying contributed to predictive specificity. Hopelessness-suicidal ideation predicted concurrent and future affective disorder; generalised worrying predicted concurrent and future anxiety, specifically concurrent generalised anxiety disorders. Generalised worrying was negatively associated with behaviour disorders. LIMITATIONS: The analyses of gender differences and the prediction of specific disorders was limited due to a low frequency of disorders other than depression. CONCLUSIONS: The bifactor model was able to differentiate concurrent and predict future clinical diagnoses. This can inform the development of targeted as well as non-specific interventions for prevention and treatment of different disorders.

Observation and applications of single-electron charge signals in the XENON100 experiment

The XENON100 dark matter experiment uses liquid xenon in a time projection chamber (TPC) to measure xenon nuclear recoils resulting from the scattering of dark matter weakly interacting massive particles (WIMPs). In this paper, we report the observation of single-electron charge signals which are not related to WIMP interactions. These signals, which show the excellent sensitivity of the detector to small charge signals, are explained as being due to the photoionization of impurities in the liquid xenon and of the metal components inside the TPC. They are used as a unique calibration source to characterize the detector. We explain how we can infer crucial parameters for the XENON100 experiment: the secondary-scintillation gain, the extraction yield from the liquid to the gas phase and the electron drift velocity.