TESTING THE EFFICIENCY OF MARKETS IN THE 2002 WORLD CUP

Trading data from the gambling market for the 2002 World Cup provide a unique window through which to test theories of market efficiency.  This market provides many of the benefits of a laboratory experiment, but with much higher stakes, experienced participants, and a naturally-occurring environment.  The primary drawback of the data is the relatively small number of trades.  The evidence concerning market efficiency is mixed.  Although markets respond strongly to goals being scored, there is some evidence that prices continue to trend higher for 10-15 minutes after a goal.  We also observe systematically negative returns for bets on the pre-game favorite, consistent with the biases seen in wagering on other sports.  We document the endogenous emergence of market makers.  These market makers are involved in a large share of trades.  Increasing from two active market makers to five or more market makers does not appear to improve the functioning of the market.  On average, the market makers earn slightly negative returns, implying that other traders are able to identify situations in which market makers are setting inefficient price

Early Natural Stimulation through Environmental Enrichment Accelerates Neuronal Development in the Mouse Dentate Gyrus

The dentate gyrus is the primary afferent into the hippocampal formation, with important functions in learning and memory. Granule cells, the principle neuronal type in the dentate gyrus, are mostly formed postnatally, in a process that continues into adulthood. External stimuli, including environmental enrichment, voluntary exercise and learning, have been shown to significantly accelerate the generation and maturation of dentate granule cells in adult rodents. Whether, and to what extent, such environmental stimuli regulate the development and maturation of dentate granule cells during early postnatal development is largely unknown. Furthermore, whether natural stimuli affect the synaptic properties of granule cells had been investigated neither in newborn neurons of the adult nor during early development. To examine the effect of natural sensory stimulation on the dentate gyrus, we reared newborn mice in an enriched environment (EE). Using immunohistochemistry, we showed that dentate granule cells from EE-reared mice exhibited earlier morphological maturation, manifested as faster peaking of doublecortin expression and elevated expression of mature neuronal markers (including NeuN, calbindin and MAP2) at the end of the second postnatal week. Also at the end of the second postnatal week, we found increased density of dendritic spines across the entire dentate gyrus, together with elevated levels of postsynaptic scaffold (post-synaptic density 95) and receptor proteins (GluR2 and GABAARγ2) of excitatory and inhibitory synapses. Furthermore, dentate granule cells of P14 EE-reared mice had lower input resistances and increased glutamatergic and GABAergic synaptic inputs. Together, our results demonstrate that EE-rearing promotes morphological and electrophysiological maturation of dentate granule cells, underscoring the importance of natural environmental stimulation on development of the dentate gyrus

Self-selection and variations in the laboratory measurement of other-regarding preferences across subject pools: evidence from one college student and two adult samples

We measure the other-regarding behavior in samples from three related populations in the upper Midwest of the United States: college students, non-student adults from the community surrounding the college, and adult trainee truckers in a residential training program. The use of typical experimental economics recruitment procedures made the first two groups substantially self-selected. Because the context reduced the opportunity cost of participating dramatically, 91 % of the adult trainees solicited participated, leaving little scope for self-selection in this sample. We find no differences in the elicited other-regarding preferences between the self-selected adults and the adult trainees, suggesting that selection is unlikely to bias inferences about the prevalence of other-regarding preferences among non-student adult subjects. Our data also reject the more specific hypothesis that approval-seeking subjects are the ones most likely to select into experiments. Finally, we observe a large difference between self-selected college students and self-selected adults: the students appear considerably less pro-social

Analysis of shared heritability in common disorders of the brain

ience, this issue p. eaap8757 Structured Abstract INTRODUCTION Brain disorders may exhibit shared symptoms and substantial epidemiological comorbidity, inciting debate about their etiologic overlap. However, detailed study of phenotypes with different ages of onset, severity, and presentation poses a considerable challenge. Recently developed heritability methods allow us to accurately measure correlation of genome-wide common variant risk between two phenotypes from pools of different individuals and assess how connected they, or at least their genetic risks, are on the genomic level. We used genome-wide association data for 265,218 patients and 784,643 control participants, as well as 17 phenotypes from a total of 1,191,588 individuals, to quantify the degree of overlap for genetic risk factors of 25 common brain disorders. RATIONALE Over the past century, the classification of brain disorders has evolved to reflect the medical and scientific communities' assessments of the presumed root causes of clinical phenomena such as behavioral change, loss of motor function, or alterations of consciousness. Directly observable phenomena (such as the presence of emboli, protein tangles, or unusual electrical activity patterns) generally define and separate neurological disorders from psychiatric disorders. Understanding the genetic underpinnings and categorical distinctions for brain disorders and related phenotypes may inform the search for their biological mechanisms. RESULTS Common variant risk for psychiatric disorders was shown to correlate significantly, especially among attention deficit hyperactivity disorder (ADHD), bipolar disorder, major depressive disorder (MDD), and schizophrenia. By contrast, neurological disorders appear more distinct from one another and from the psychiatric disorders, except for migraine, which was significantly correlated to ADHD, MDD, and Tourette syndrome. We demonstrate that, in the general population, the personality trait neuroticism is significantly correlated with almost every psychiatric disorder and migraine. We also identify significant genetic sharing between disorders and early life cognitive measures (e.g., years of education and college attainment) in the general population, demonstrating positive correlation with several psychiatric disorders (e.g., anorexia nervosa and bipolar disorder) and negative correlation with several neurological phenotypes (e.g., Alzheimer's disease and ischemic stroke), even though the latter are considered to result from specific processes that occur later in life. Extensive simulations were also performed to inform how statistical power, diagnostic misclassification, and phenotypic heterogeneity influence genetic correlations. CONCLUSION The high degree of genetic correlation among many of the psychiatric disorders adds further evidence that their current clinical boundaries do not reflect distinct underlying pathogenic processes, at least on the genetic level. This suggests a deeply interconnected nature for psychiatric disorders, in contrast to neurological disorders, and underscores the need to refine psychiatric diagnostics. Genetically informed analyses may provide important "scaffolding" to support such restructuring of psychiatric nosology, which likely requires incorporating many levels of information. By contrast, we find limited evidence for widespread common genetic risk sharing among neurological disorders or across neurological and psychiatric disorders. We show that both psychiatric and neurological disorders have robust correlations with cognitive and personality measures. Further study is needed to evaluate whether overlapping genetic contributions to psychiatric pathology may influence treatment choices. Ultimately, such developments may pave the way toward reduced heterogeneity and improved diagnosis and treatment of psychiatric disorders