The profile of brain structural abnormalities in schizophrenia is still not fully understood, despite decades of research using brain scans. To validate a prospective meta-analysis approach to analyzing multi-center neuroimaging data, we analyzed brain MRI scans from 2,028 schizophrenia patients and 2,540 healthy controls, assessed with standardized methods at 15 centers worldwide. We identified subcortical brain volumes that differentiated patients from controls, and ranked them according to their effect sizes. Compared to healthy controls, patients with schizophrenia had smaller hippocampus (Cohen’s d=−0.46), amygdala (d=−0.31), thalamus (d=−0.31), accumbens (d=−0.25), and intracranial volumes (d=−0.12) and larger pallidum (d=0.21) and lateral ventricle volumes (d=0.37). Putamen and pallidum volume augmentations were positively associated with duration of illness and hippocampal deficits scaled with the proportion of unmedicated patients. Worldwide cooperative analyses of brain imaging data support a profile of subcortical abnormalities in schizophrenia that is consistent with that based on traditional meta-analytic approaches. This first ENIGMA Schizophrenia Working Group study validates that collaborative data analyses can readily be employed across brain phenotypes and disorders and encourages analysis and data sharing efforts to further our understanding of severe mental illness.

Major depressive disorder (MDD) is a common, debilitating illness with high prevalence of comorbid anxiety. The incidence of depression and of comorbid anxiety is much higher in women than in men. These gender biases appear after puberty and their etiology is mostly unknown. Selective breeding of the Wistar Kyoto (WKY) rat strain, an accepted model of adult and adolescent depression, resulted in two fully inbred substrains. Adult WKY more immobile (WMI) rats of both sexes consistently show increased depression-like behavior in the forced swim test when compared with the control WKY less immobile (WLI) strain. In contrast, here we show that while adult female WMIs and WLIs both display high anxiety-like behaviors, only WLI males, but not WMI males, show this behavior. Moreover, the behavioral profile of WMI males is consistent from early adolescence to adulthood, but the high depression-and anxiety-like behaviors of the female WMIs appear only in adulthood. These sex-specific behavioral patterns are paralleled by marked sex differences in hippocampal gene expression differences established by genome-wide transcriptional analyses of 13th generation WMIs and WLIs. Moreover, sex-and age-specific differences in transcript levels of selected genes are present in the hippocampus of the current, fully inbred WMIs and WLIs. Thus, the contribution of specific genes and/or the influence of the gonadal hormonal environment to depression-and anxiety-like behaviors may differ between male and female WMIs, resulting in their distinct behavioral and transcriptomic profiles despite shared sequences of the somatic chromosomes.

A search for the pair production of scalar top quarks,t, has been performed in 360 pb −1 of data from pp collisions at a center-of-mass energy of 1.96 TeV, collected by the DØ detector at the Fermilab Tevatron collider. Thet decay mode considered ist → cχ 0 1 , whereχ 0 1 is the lightest supersymmetric particle. The topology analyzed therefore consists of a pair of acoplanar heavy-flavor jets with missing transverse energy. The data and standard model expectation are in agreement, and a 95% C.L. exclusion domain in the (mt , mχ0 ciated with the left-and right-handed degrees of freedom of each ordinary quark. The mass eigenstates result from the diagonalization of a mass matrix, with elements determined by the specific SUSY-breaking pattern. A light SUSY partner of the top quark, or stop, is a generic prediction of models in which the scalar quark masses are equal at the grand unification scale. A first reason is that, due to the impact of the large top quark Yukawa coupling in the renormalization group equations, DØ Collaboration / Physics Letters B 645 (2007) 119-127 123 the diagonal elements of the mass matrix are driven to values smaller than those for the other scalar quarks at the electroweak scale [2]. A second reason is that the off-diagonal terms are proportional to the relevant quark mass, and hence are much larger in the case of the top quark. The mass eigenstates are therefore broadly split, with the mass of the lighter stopt thus driven to an even lower value [3]. Finally, a light stop is a necessary ingredient in the context of electroweak baryogenesis [4].In models with R-parity conservation [5], the lightest SUSY particle (LSP) is stable, and cosmological constraints imply that it should be neutral and colorless [6]. In a large class of SUSY models, the lightest of the neutralinos-the mass eigenstates resulting from the mixing of the SUSY partners of the neutral gauge and Higgs bosons-is the LSP, which furthermore appears as a viable dark matter candidate. In the following, it will be assumed that R-parity is conserved and that the LSP is the lightest neutralinoχ is considered, and it is assumed that t → cχ 0 1 , a flavor-changing loop decay [7], is the only relevant decay mode, i.e., that the tree-level four-body decays [8] t → bff χ 0 1 can be neglected. In pp collisions, stop pair production proceeds via qq annihilation and gluon-gluon fusion. The cross section has very little dependence on SUSY parameters other than the stop mass. At the center-of-mass energy of 1.96 TeV available in Run II of the Fermilab Tevatron collider, it ranges from 15 to 2.25 pb for stop masses from 100 to 140 GeV, as calculated at nextto-leading order (NLO) with PROSPINO [9], for equal renormalization and factorization scales μ rf = mt and using the CTEQ6.1M parton distribution functions (PDFs) [10]. The final state topology resulting from thet → cχ 0 1 decay is a pair of acoplanar jets, with large missing transverse energy / E T carried away by the two weakly interacting LSPs. Previous searches in this...

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