The role of the nucleus accumbens in knowing when to respond

While knowing what to expect is important, it is equally important to know when to expect it and to respond accordingly. This is apparent even in simple Pavlovian training situations in which animals learn to respond more strongly closer to reward delivery. Here we report that the nucleus accumbens core, an area well-positioned to represent information about the timing of impending rewards, plays a critical role in this timing function.     

Depression is not an inevitable outcome of disclosure avoidance: HIV stigma and mental health in a cohort of HIV-infected individuals from Southern India

Previous research has shown that HIV stigma in India can be characterized by a framework dividing manifestations into enacted (discrimination), vicarious (hearing stories of discrimination), felt normative (perceptions of stigma's prevalence), and internalized stigma (personal endorsement of stigma beliefs). We examined whether this framework could explain associations among stigma, efforts to avoid HIV serostatus disclosure, and depression symptoms in a cohort of 198 HIV-infected individuals from Southern India who were followed up for one year as part of a study of antiretroviral adherence. Prior studies had suggested that disclosure avoidance was a primary outcome of stigma and that impaired well-being was a primary outcome of disclosure avoidance. Analyses from our longitudinal research revealed that the pattern of associations among stigma, disclosure avoidance, and depression symptoms remained consistent over time. Enacted and vicarious stigmas were correlated with felt normative stigma beliefs. In turn, felt normative stigma was correlated with disclosure avoidance. And, enacted stigma, internalized stigma, and disclosure avoidance were all associated with depression symptoms. However, even though the overall framework held together, internalized stigma and depression symptoms dropped significantly over time while other components remained unchanged. These findings suggest that, although HIV stigma may limit disclosure, it does not invariably lead to psychological maladjustment. Amidst ongoing perceptions and experiences of stigma, HIV-positive individuals can achieve significant improvements in their acceptance of the disease and in mental well-being.     

The serotonin transporter promoter polymorphism and childhood positive and negative emotionality

Association studies of the serotonin transporter promoter polymorphism (5-HTTLPR) and negative emotionality (NE) are inconclusive. However, emerging evidence suggests that the association between this polymorphism and NE may be influenced by levels of another temperament trait, positive emotionality (PE). Therefore, this study examined whether the association between the 5-HTTLPR and NE was moderated by PE. A community sample of 413 three-year-old children completed a standardized battery of laboratory tasks designed to tap temperamental emotionality. Children were also genotyped for the 5-HTTLPR. No direct association between 5-HTTLPR genotype and NE was found. However, the interaction of child PE and NE predicted 5-HTTLPR genotype. Furthermore, children with a short allele who were also low in PE had significantly greater NE than children without a short allele or children with high PE. Our findings suggest that the short allele of the 5-HTTLPR is associated with NE only in the context of low PE. Inconsistent links between NE and this gene in previous research may stem from the failure to consider other temperament traits that moderate associations.     

Vegetative state: efforts to curb misdiagnosis

Media reports on the case of Rom Houben have constituted a new reminder of the risks of misdiagnosis with cases with apparent vegetative state, particularly when following the clinical consensus of the care team as diagnostic criterion. Systematic use of behavioral and non-behavioral assessment strategies (e.g., behavioral scales, event-related potentials, and neuro-imaging) may help reduce the aforementioned risks. A new learning assessment strategy could also be considered part of the assessment to extend the evaluation process. Signs of learning might be viewed as forms of concrete knowledge representing a basic level of non-reflective consciousness.     

Paradoxical cross-over due to attention to high or low spatial frequencies

The mechanisms underlying the right hemisphere's dominance for spatial and attentional functions lacks a comprehensively explanation. For example, perceptual biases, as observed in line bisection and related tasks, might be caused by an attentional asymmetry or by perceptual processes such as a specialization of the left and right hemisphere for high and low spatial frequencies (SFs), respectively. Here we used the gratingscales task to measure perceptual bias in SF judgements, and we cued participants' attention either to high or low SFs. Participants showed a leftward bias when comparing the high SF components of the stimulus, and a rightward bias when comparing the low SF components-opposite to what would be expected from a hemispheric lateralization for SFs. Two control experiments used different strategies to manipulate the width of the attentional window. However, we observed no influence on perceptual bias, thus ruling out the possibility that the results in Experiment 1 were due to differences in attentional window size. These data support the idea of an attentional asymmetry underlying perceptual bias. Our results provide novel support for the role of attentional asymmetry in perceptual biases.     

Inequity in Hindu–Muslim Riots: A Test of Two Biases1

During the past 50 years, substantially more Muslims than Hindus have died in riots in India. This study examined and found support for 2 possible individual‐level reasons that are consistent with this disproportionate number of deaths. First, Hindus, compared to Muslims, considered historical incidents to be more important for contemporary Hindu–Muslim relations. Second, Hindus showed an ultimate group bias in that they generally valued Hindu lives more than Muslim lives, whereas Muslims showed no difference in the valuation of Hindu and Muslim lives. Together, these results are consistent with an equity notion that Hindus consider as relevant input factors both historical incidents and perceptions that in‐group members’ lives are more valuable than are out‐group members’ lives.     

Predicting General Well-Being From Emotional Intelligence and Three Broad Personality Traits

This paper examined the joint predictive effects of trait emotional intelligence (trait-EI), Extraversion, Conscientiousness, and Neuroticism on 2 facets of general well-being and job satisfaction. An employed community sample of 123 individuals from the Indian subcontinent participated in the study, and completed measures of the five-factor model of personality, trait-EI, job satisfaction, and general well-being facets worn-out and up-tight . Trait-EI was related but distinct from the 3 personality variables. Trait-EI demonstrated the strongest correlation with job satisfaction, but predicted general well-being no better than Neuroticism. In regression analyses, trait-EI predicted between 6% and 9% additional variance in the well-being criteria, beyond the 3 personality traits. It was concluded that trait-EI may be useful in examining dispositional influences on psychological well-being.     

Ceftriaxone rescues hippocampal neurons from excitotoxicity and enhances memory retrieval in chronic hypobaric hypoxia

Exposure to high altitude is known to cause impairment in cognitive functions in sojourners. The molecular events leading to this behavioral manifestation, however, still remain an enigma. The present study aims at exploring the nature of memory impairment occurring on chronic exposure to hypobaric hypoxia and the possible role of glutamate in mediating it. Increased ionotropic receptor stimulation by glutamate under hypobaric hypoxic conditions could lead to calcium mediated excitotoxic cell death resulting in impaired cognitive functions. Since glutamate is cleared from the synapse by the Glial Glutamate Transporter, upregulation of the transporter can be a good strategy in preventing excitotoxic cell death. Considering previous reports on upregulation of the expression of Glial Glutamate Transporter on ceftriaxone administration, the therapeutic potential of ceftriaxone in ameliorating hypobaric hypoxia induced memory impairment was investigated in male Sprague Dawley rats. Exposure to hypobaric hypoxia equivalent to an altitude of 7600 m for 14 days lead to oxidative stress, chromatin condensation and neuronal degeneration in the hippocampus. This was accompanied by delayed memory retrieval as evident from increased latency and pathlength in Morris Water Maze. Administration of ceftriaxone at a dose of 200 mg/kg for 7 days and 14 days during the exposure on the other hand improved the performance of rats in the water maze along with decreased oxidative stress and enhanced neuronal survival when compared to hypoxic group without drug administration. An increased expression of Glial Glutamate Transporter was also observed following drug administration indicating faster clearance of glutamate from the synapse. The present study not only brings to light the effect of longer duration of exposure to hypobaric hypoxia on the memory functions, but also indicates the pivotal role played by glutamate in mediating excitotoxic neuronal degeneration at high altitude. The therapeutic potential of ceftriaxone in providing neuroprotection in excitotoxic conditions by increasing Glial Glutamate Transporter expression and thereby enhancing glutamate uptake from the synapse has also been explored.