Trust in Private and Common Property Experiments

We report the results from a series of experiments designed to investigate behavior in two settings that are frequently posited in the policy literature as generating different outcomes: private property and common property. The experimental settings closely parallel earlier experimental studies of the investment or trust game. The primary research question relates to the effect of the initial allocation of property rights on the level of trust that subjects will extend to others with whom they are linked. We find that assigning the initial endowments as common property of each of N pairs of a first mover and second mover leads to marginally greater cooperation or trust than when the initial endowments are fully owned by the two individual movers as their, respective, private property. Subjectsâ?? decisions are also shown to be correlated with attitudes toward trust and fairness that are measured in post-experiment questionnaires.

A Closer Look at Self-Esteem, Perceived Social Support, and Coping Strategy: A Prospective Study of Depressive Symptomatology Across the Transition to College

The first year of college is a significant life transition, which is often characterized by stress and may contribute to the development or exacerbation of depressive symptoms. Due to the considerable negative outcomes that are associated with depressive symptoms across the lifespan, it is important to understand the mechanisms and pathways through which depressive symptoms arise. This prospective study examines the mediating and moderating roles of perceived social support and disengagement coping on the association between self-esteem and depressive symptomatology in a sample of 1,118 first-year college students. Results of longitudinal cross-lagged path analyses indicate that self-esteem predicts depressive symptomatology via perceived social support and disengagement coping. The association between self-esteem and perceived social support appear to be bidirectional, in that level of self-esteem predicts perceived social support, and vice versa. Furthermore, disengagement coping was found to moderate the effect of self-esteem on depressive symptomatology, in that increased levels of disengagement coping led to greater depressive symptoms within the context of both high and low self-esteem. However, this pattern was not observed at lower levels of disengagement coping, which indicates high levels of disengagement coping as a particular risk factor for depressive symptomatology, diminishing the advantage of high self-esteem

The impact of multiple memory formation on dendritic complexity in the hippocampus and anterior cingulate cortex assessed at recent and remote time points

Consolidation processes, involving synaptic and systems level changes, are suggested to stabilize memories once they are formed. At the synaptic level, dendritic structural changes are associated with long-term memory storage. At the systems level, memory storage dynamics between the hippocampus and anterior cingulate cortex (ACC) may be influenced by the number of sequentially encoded memories. The present experiment utilized Golgi-Cox staining and neuron reconstruction to examine recent and remote structural changes in the hippocampus and ACC following training on three different behavioral procedures. Rats were trained on one hippocampal-dependent task only (a water maze task), two hippocampal-dependent tasks (a water maze task followed by a radial arm maze task), or one hippocampal-dependent and one non-hippocampal-dependent task (a water maze task followed by an operant conditioning task). Rats were euthanized recently or remotely. Brains underwent Golgi-Cox processing and neurons were reconstructed using Neurolucida software (MicroBrightField, Williston, VT, USA). Rats trained on two hippocampal-dependent tasks displayed increased dendritic complexity compared to control rats, in neurons examined in both the ACC and hippocampus at recent and remote time points. Importantly, this behavioral group showed consistent, significant structural differences in the ACC compared to the control group at the recent time point. These findings suggest that taxing the demand placed upon the hippocampus, by training rats on two hippocampal-dependent tasks, engages synaptic and systems consolidation processes in the ACC at an accelerated rate for recent and remote storage of spatial memories

Partisan Asymmetries in Online Political Activity

We examine partisan differences in the behavior, communication patterns and social interactions of more than 18,000 politically-active Twitter users to produce evidence that points to changing levels of partisan engagement with the American online political landscape. Analysis of a network defined by the communication activity of these users in proximity to the 2010 midterm congressional elections reveals a highly segregated, well clustered partisan community structure. Using cluster membership as a high-fidelity (87% accuracy) proxy for political affiliation, we characterize a wide range of differences in the behavior, communication and social connectivity of left- and right-leaning Twitter users. We find that in contrast to the online political dynamics of the 2008 campaign, right-leaning Twitter users exhibit greater levels of political activity, a more tightly interconnected social structure, and a communication network topology that facilitates the rapid and broad dissemination of political information.Comment: 17 pages, 10 figures, 6 table

Altered hippocampal lipid profile following acute postnatal exposure to Di(2-Ethylhexyl) phthalate in rats

Slight changes in the abundance of certain lipid species in the brain may drastically alter normal neurodevelopment via membrane stability, cell signalling, and cell survival. Previous findings have demonstrated that postnatal exposure to di (2-ethylhexyl) phthalate (DEHP) disrupts normal axonal and neural development in the hippocampus. The goal of the current study was to determine whether postnatal exposure to DEHP alters the lipid profile in the hippocampus during postnatal development. Systemic treatment with 10 mg/kg DEHP during postnatal development led to elevated levels of phosphatidylcholine and sphingomyelin in the hippocampus of female rats. There was no effect of DEHP exposure on the overall abundance of phosphatidylcholine or sphingomyelin in male rats or of lysophosphatidylcholine in male or female rats. Individual analyses of each identified lipid species revealed 10 phosphatidylcholine and six sphingomyelin lipids in DEHP-treated females and a single lysophosphatidylcholine in DEHP-treated males with a two-fold or higher increase in relative abundance. Our results are congruent with previous work that found that postnatal exposure to DEHP had a near-selective detrimental effect on hippocampal development in males but not females. Together, results suggest a neuroprotective effect of these elevated lipid species in females

Intra-Accumbens Injection of a Dopamine Aptamer Abates MK-801-Induced Cognitive Dysfunction in a Model of Schizophrenia

Systemic administration of the noncompetitive NMDA-receptor antagonist, MK-801, has been proposed to model cognitive deficits similar to those seen in patients with schizophrenia. The present work investigated the ability of a dopamine-binding DNA aptamer to regulate these MK-801-induced cognitive deficits when injected into the nucleus accumbens. Rats were trained to bar press for chocolate pellet rewards then randomly assigned to receive an intra-accumbens injection of a DNA aptamer (200 nM; n = 7), tris buffer (n = 6) or a randomized DNA oligonucleotide (n = 7). Animals were then treated systemically with MK-801 (0.1 mg/kg) and tested for their ability to extinguish their bar pressing response. Two control groups were also included that did not receive MK-801. Data revealed that injection of Tris buffer or the random oligonucleotide sequence into the nucleus accumbens prior to treatment with MK-801 did not reduce the MK-801-induced extinction deficit. Animals continued to press at a high rate over the entire course of the extinction session. Injection of the dopamine aptamer reversed this MK-801-induced elevation in lever pressing to levels as seen in rats not treated with MK-801. Tests for activity showed that the aptamer did not impair locomotor activity. Results demonstrate the in vivo utility of DNA aptamers as tools to investigate neurobiological processes in preclinical animal models of mental health disease

Is popular radio a source of exposure to alcohol references in mid to later life?:A content analysis

Background There is concern around alcohol consumption in mid to later life yet little understanding about what influences this behaviour. No previous research has explored the extent to which adults in mid to later life may be exposed to alcohol references in the media. This project aimed to determine the frequency of alcohol references on radio stations with a high proportion of listeners in mid to later life. Methods Content analysis of alcohol references on four popular UK music-based radio stations with a high proportion of listeners aged 55–64 years over three time points. Results Alcohol references occur frequently, but vary by time of year and type of radio station. When alcohol is mentioned its consumption is portrayed as the norm, without negative consequences. On three commercial stations, the majority of mentions came from advertising, whereas on BBC Radio 2 nearly all references were talk-based. All adverts for direct promotion of alcohol were by supermarkets. Alcohol was frequently associated with celebrations, socializing or something to consume for its own sake. Conclusions Adults in the age group 55–64 may be exposed to references to alcohol that could serve to reinforce norms of consumption of alcohol and promote purchases of cheap alcohol