The Effects of Social Ties on Coordination: Conceptual Foundations for an Empirical Analysis

International audienceThis paper investigates the influence that social ties can have on behavior. After defining the concept of social ties that we consider, we introduce an original model of social ties. The impact of such ties on social preferences is studied in a coordination game with outside option. We provide a detailed game theoretical analysis of this game while considering various types of players, i.e., self-interest maximizing, inequity averse, and fair agents. In addition to these approaches that require strategic reasoning in order to reach some equilibrium, we also present an alternative hypothesis that relies on the concept of team reasoning. After having discussed the differences between the latter and our model of social ties, we show how an experiment can be designed so as to discriminate among the models presented in the paper

Input-specific control of reward and aversion in the ventral tegmental area

Ventral tegmental area (VTA) dopamine neurons have important roles in adaptive and pathological brain functions related to reward and motivation. However, it is unknown whether subpopulations of VTA dopamine neurons participate in distinct circuits that encode different motivational signatures, and whether inputs to the VTA differentially modulate such circuits. Here we show that, because of differences in synaptic connectivity, activation of inputs to the VTA from the laterodorsal tegmentum and the lateral habenula elicit reward and aversion in mice, respectively. Laterodorsal tegmentum neurons preferentially synapse on dopamine neurons projecting to the nucleus accumbens lateral shell, whereas lateral habenula neurons synapse primarily on dopamine neurons projecting to the medial prefrontal cortex as well as on GABAergic (γ-aminobutyric-acid-containing) neurons in the rostromedial tegmental nucleus. These results establish that distinct VTA circuits generate reward and aversion, and thereby provide a new framework for understanding the circuit basis of adaptive and pathological motivated behaviours.National Institutes of Health (U.S.) (Grant NIH NS069375)JPB FoundationNational Institute of Mental Health (U.S.

Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress

In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse

Spectral domain optical coherence tomography in patients after successful management of postoperative endophthalmitis following cataract surgery by pars plana vitrectomy.

BACKGROUND: Acute severe postoperative endophthalmitis may lead to severe vision loss. The aim of this study was the analysis of macular microstructure imaged by spectral domain optical coherence tomography in patients after pars plana vitrectomy due to postcataract endophthalmitis. METHODS: A cross sectional study was carried out in 17 patients who had cataract surgery in both eyes and underwent unilateral pars plana vitrectomy due to postcataract endophthalmitis. Postoperative best corrected visual acuity was determined in both eyes. Evaluation of macular thickness, macular volume, peripapillary retinal nerve fiber layer thickness and choroidal thickness using enhanced depth imaging technique was performed by spectral domain optical coherence tomography. The measurements obtained in the operated eye were compared to the fellow eye by Wilcoxon matched pair test. Correlation test was performed by Spearman rank order. RESULTS: A mean postoperative best corrected visual acuity of 63 +/- 30 ETDRS letters versus 75 +/- 21 letters was achieved in the study and fellow eyes, respectively, after a mean of 5.3 +/- 4.5 months (p = 0.1). The mean macular thickness was 320.6 +/- 28.8 mum SD in the study eyes compared to 318.4 +/- 18.8 mum in the fellow eyes (p = 0.767). No differences were noted in macular volume (p = 0.97) and in peripapillary retinal nerve fiber layer thickness (p = 0.31). Choroidal thickness was significantly lower in the study eyes compared to the fellow eyes (p = 0.018). Epiretinal membrane was found in 7 eyes after endophthalmitis, while in the fellow eyes only in 3 cases (p = 0.13, Fisher's exact test). CONCLUSION: Choroidal thickness decreased significantly after endophthalmitis, but there was no functional correlation with the changes in choroidal microstructure. The development of epiretinal membranes may be associated with either vitrectomy or endophthalmitis in the history. Absence of other significant structural and morphological findings shows that successful treatment may guarantee good clinical results even in long term after this severe postoperative complication

Life and living in advanced age: a cohort study in New Zealand - Te Puāwaitanga o Nga Tapuwae Kia Ora Tonu, LiLACS NZ: Study protocol

The number of people of advanced age (85 years and older) is increasing and health systems may be challenged by increasing health-related needs. Recent overseas evidence suggests relatively high levels of wellbeing in this group, however little is known about people of advanced age, particularly the indigenous Māori, in Aotearoa, New Zealand. This paper outlines the methods of the study Life and Living in Advanced Age: A Cohort Study in New Zealand. The study aimed to establish predictors of successful advanced ageing and understand the relative importance of health, frailty, cultural, social & economic factors to successful ageing for Māori and non-Māori in New Zealand

Relation of Sources of Systemic Fluoride to Prevalence of Dental Fluorosis

The prevalence of dental fluorosis in a nonfluoridated area was determined and related to the reported fluoride ingestion histories of the children examined. A convenience sample of 543 schoolchildren in rural areas of Michigan was examined for fluorosis using the Tooth Surface Index of Fluorosis. Questionnaires that asked about previous use of fluorides were sent to parents of all children examined. The response rate was 76 percent (412 usable questionnaires). A criterion for inclusion in the data analysis stipulated that only fluorosed surfaces that occurred bilaterally would be included. Fluorosis was found on 7 percent of all tooth surfaces and only in the mild form. Twenty-two percent of the subjects were classified as having fluorosis. Dietary supplement was the only fluoride that was found to be significantly related to the occurrence of fluorosis. A greater proportion of the subjects with fluorosis fisted physicians, rather than dentists, as the source of fluoride prescriptions. The results demonstrate similarities to the fluorosis reported in other studies in non-fluoridated areas, but also suggest the need to minimize the occurrence of fluorosis through proper assessment of a child's fluoride exposure and the judicious use of additional fluoride.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65695/1/j.1752-7325.1989.tb02030.x.pd

Coding by Choice: A Transitional Analysis of Social Participation Patterns and Programming Contributions in the Online Scratch Community

While massive online communities have drawn the attention of researchers and educators on their potential to support active collaborative work, knowledge sharing, and user-generated content, few studies examine participation in these communities at scale. The little research that does exist attends almost solely to adults rather than communities to support youths’ learning and identity development. In this chapter, we tackle two challenges related to understanding social practices that support learning in massive social networking forums where users engage in design. We examined a youth programmer community, called Scratch.mit.edu, that garners the voluntary participation of millions of young people worldwide. We report on site-wide distributions and patterns of participation that illuminate the relevance of different online social practices to ongoing involvement in the online community. Drawing on a random sample of more than 5000 active users of Scratch.mit.edu over a 3-month time period in early 2012, we examine log files that captured the frequency of three types of social practices that contribute to enduring participation: DIY participatory activities, socially supportive actions, and socially engaging interactions. Using latent transition analysis, we found (1) distinct patterns of participation (classes) across three time points (e.g., high networkers who are generally active, commenters who focus mainly on social participation, downloaders engaging in DIY participatory activities), (2) unique migration changes in class membership across time, (3) relatively equal gender representation across these classes, and (4) importance of membership length (or age) in terms of class memberships. In the discussion, we review our approach to analysis and outline implications for the design and study of online communities and tools for youth