Non-invasive estimation of local field potentials for neuroprosthesis control

Recent experiments have shown the possibility of using the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions, i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using an identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using a different number of electrodes.

Understanding extraverts' enjoyment of social situations: the importance of pleasantness

Extraversion is a broad, multifaceted trait, yet researchers are still unsure of its defining characteristics. One possibility is that the essential feature of extraversion is the tendency to enjoy social situations. An alternative possibility is that extraversion represents sensitivity to rewards and the tendency to experience pleasant affect. In three studies, participants rated situations that varied on two dimensions: (a) whether they were social or nonsocial and (b) whether they were very pleasant, moderately pleasant, moderately unpleasant, or very unpleasant. Extraverts only rated social situations more positively than introverts did when the situations were pleasant, and extraverts also rated nonsocial situations more positively than introverts did if the situations were pleasant. Thus, the pleasantness of situations was more important than whether they were social or nonsocial in determining extraverts' and introverts' enjoyment.     

EthoVision: A versatile video tracking system for automation of behavioral experiments

The need for automating behavioral observations and the evolution of systems developed for that purpose is outlined. Video tracking systems enable researchers to study behavior in a reliable and consistent way and over longer time periods than if they were using manual recording. To overcome limitations of currently available systems, we have designed EthoVision, an integrated system for automatic recording of activity, movement, and interactions of animals. The EthoVision software is presented, highlighting some key features that separate EthoVision from other systems: easy file management, independent variable definition, flexible arena and zone design, several methods of data acquisition allowing identification and tracking of multiple animals in multiple arenas, and tools for visualization of the tracks and calculation of a range of analysis parameters. A review of studies using EthoVision is presented, demonstrating the system’s use in a wide variety of applications. Possible future directions for development are discussed.     

The relationship between self-reported received and perceived social support: A meta-analytic review

Social support is broad term encompassing a variety of constructs, including support perceptions (perceived support) and receipt of supportive behaviors (received support). Of these constructs, only perceived support has been regarded as consistently linked to health, and researchers have offered differing assessments of the strength of the received-perceived support relationship. An overall estimate of the received-perceived support relationship would clearly further the dialogue on the relationship between received and perceived support and thus assist in the theoretical development of the field. This study evaluated all available studies using the Inventory of Socially Supportive Behaviors (ISSB; Barrera, Sandler, & Ramsey, 1981, American Journal of Community Psychology, 9, 435–447) and any measure of perceived social support. Using effect sizes from 23 studies, we found an average correlation of r = .35, p < .001. Implications of this estimate for further development of models of social support as well as interventions to enhance social support are discussed.     

Adaptation and the Set-Point Model of Subjective Well-Being: Does Happiness Change After Major Life Events?

ABSTRACT— Hedonic adaptation refers to the process by which individuals return to baseline levels of happiness following a change in life circumstances. Dominant models of subjective well-being (SWB) suggest that people can adapt to almost any life event and that happiness levels fluctuate around a biologically determined set point that rarely changes. Recent evidence from large-scale panel studies challenges aspects of this conclusion. Although inborn factors certainly matter and some adaptation does occur, events such as divorce, death of a spouse, unemployment, and disability are associated with lasting changes in SWB. These recent studies also show that there are considerable individual differences in the extent to which people adapt. Thus, happiness levels do change, and adaptation is not inevitable.     

Mid-life stress is associated with both up- and down-regulation of markers of humoral and cellular immunity

Perception of stress with consequent activation of a neuroendocrine cascade causes changes in immune function that may be bi-directional, with alterations in basal levels of biological parameters outside the optimal range. In this cross-sectional study of 302 healthy persons (males 56.3%, females 43.7%) aged 41-46 years, higher stress levels, as assessed by questionnaire measures of recurrent and recent perceived stress, were associated with a 4-fold greater risk of having a high compared to mid-range serum neopterin concentration, indicating activation of cellular immune mechanisms [adjusted odds ratio, OR; (95% confidence intervals, CI): Low stress=1.00 (reference group); Medium stress=4.13 (1.51, 11.29); High stress=4.63, (1.35, 15.83), p for trend=0.01]. Higher stress levels were associated with a 3-fold greater risk of having signs of humoral immune activation, as indicated by salivary IgA concentration [high compared to mid-range salivary IgA: Low stress=1.00 (reference group); Medium stress=1.06 (0.48, 2.34); High stress=3.62 (1.26, 10.39), p for trend=0.02], but also a 4-fold greater risk of humoral immune depression [low compared to mid-range IgA: Low stress=1.00 (reference group); Medium stress=1.72 (0.74, 3.99); High stress=4.38 (1.47, 13.00), p for trend=0.02]. In conclusion, in this cross-sectional study, higher stress levels were associated with higher serum neopterin and both elevated and depressed salivary IgA levels. These findings emphasise the importance of considering that stress may have bi-directional effects on immune mechanisms, and are consistent with an activational effect of chronic, perceived stress on cellular immunity, and a bi-directional effect on IgA levels, one aspect of humoral immunity.     

The Optimum Level of Well-Being: Can People Be Too Happy?

ABSTRACT— Psychologists, self-help gurus, and parents all work to make their clients, friends, and children happier. Recent research indicates that happiness is functional and generally leads to success. However, most people are already above neutral in happiness, which raises the question of whether higher levels of happiness facilitate more effective functioning than do lower levels. Our analyses of large survey data and longitudinal data show that people who experience the highest levels of happiness are the most successful in terms of close relationships and volunteer work, but that those who experience slightly lower levels of happiness are the most successful in terms of income, education, and political participation. Once people are moderately happy, the most effective level of happiness appears to depend on the specific outcomes used to define success, as well as the resources that are available.     

Test of a Dynamic Stress Model for Organisational Change: Do Males and Females Require Different Models?

Cette étude a opérationnalisé et mis à l’épreuve un modèle dynamique du stress adapté au changement organisationnel en tenant compte de l’impact du sexe sur le modèle. L’échantillon était composé de 804 employés de cinq centres médicaux pour anciens combattants. Le modèle, inspiré de celui de Mack, Nelson & Quick (1998) comprenait: l’importance des retombées du changement organisationnel sur le rôle professionnel, les relations et l’environnement de travail, les opportunités, la carrière, l’incertitude et l’évaluation des problèmes à résoudre, le stress perçu et les réactions de contrôle‐évitement. On est parti de l’idée que l’évaluation jouerait un rôle de médiateur entre l’importance du changement et le stress perçu et que les réactions agiraient directement sur les évaluations et le stress perçu. L’analyse en pistes causales confirma le modèle de changement proposé sous réserve de quelques modifications, mais montra que les hommes et les femmes pouvaient revendiquer leur propre modèle. Les différences dues au sexe apparaissent dans la relation entre la perception et l’évaluation du changement; et chaque sexe présente des sources spécifiques de stress. L’évaluation jouait un rôle partiel de médiateur entre l’importance du changement et le stress perçu. Le contrôle de la situation était une stratégie plus pertinente que l’évitement aussi bien pour les hommes que pour les femmes. On réfléchit aux conséquences de ce travail pour les chercheurs et les organisations. The present study operationalised and tested a dynamic stress model for organisational change, including the interaction effect of sex on the model, on 804 employees at five VA medical centers. The model, an adaptation of Mack, Nelson, and Quick's (1998 ) model included: the amount of organisational change within job role, work relationships, job context, facility, and career; uncertainty and challenge appraisal; perceived stress; and control and avoidance coping. It was proposed that appraisal would act as a mediator between amount of change and perceived stress and that coping would have direct effects on appraisals and perceived stress. Path analyses supported the proposed change model with some modification, but indicated that males and females may require unique models. Sex differences emerged in relationships between perceptions and appraisal of change, and males and females had unique sources of stress. Appraisal acted as a partial mediator between amount of change and perceived stress. Control coping emerged as a more adaptive strategy than avoidance coping for both males and females. Implications for researchers and organisations are discussed.     

Do Social Relationships Buffer the Effects of Widowhood? A Prospective Study of Adaptation to the Loss of a Spouse

The idea that strong social relationships can buffer the negative effects of stress on well‐being has received much attention in existing literature. However, previous studies have used less than ideal research designs to test this hypothesis, making it difficult to draw firm conclusions regarding the buffering effects of social support. In this study, we examined the buffering hypothesis in the context of reaction and adaptation to widowhood in three large longitudinal datasets. We tested whether social relationships moderated reaction and adaptation to widowhood in samples of people who experienced loss of a spouse from three longitudinal datasets of nationally representative samples from Germany (N = 1,195), Great Britain (N = 562), and Australia (N = 298). We found no evidence that social relationships established before widowhood buffered either reaction or adaptation to the death of one's spouse. Similarly, social relationships that were in place during the first year of widowhood did not help widows and widowers recover from this difficult event. Social relationships acquired prior to widowhood, or those available in early stages of widowhood, do not appear to explain individual differences in adaptation to loss.     

The Logics of Strict-Tolerant Logic

Adding a transparent truth predicate to a language completely governed by classical logic is not possible. The trouble, as is well-known, comes from paradoxes such as the Liar and Curry. Recently, Cobreros, Egré, Ripley and van Rooij have put forward an approach based on a non-transitive notion of consequence which is suitable to deal with semantic paradoxes while having a transparent truth predicate together with classical logic. Nevertheless, there are some interesting issues concerning the set of metainferences validated by this logic. In this paper, we show that this logic, once it is adequately understood, is weaker than classical logic. Moreover, the logic is in a way similar to the paraconsistent logic LP.