To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Functional circuits of the human brain emerge and change dramatically over the second half of gestation. It is possible that variation in neural functional system connectivity in utero predicts individual differences in infant behavioral development, but this possibility has yet to be examined. The current study examines the association between fetal sensorimotor brain system functional connectivity and infant postnatal motor ability. Resting-state functional connectivity data was obtained in 96 healthy human fetuses during the second and third trimesters of pregnancy. Infant motor ability was measured 7 months after birth using the Bayley Scales of Infant Development. Increased connectivity between the emerging motor network and regions of the prefrontal cortex, temporal lobes, posterior cingulate, and supplementary motor regions was observed in infants that showed more mature motor functions. In addition, females demonstrated stronger fetal-brain to infant-behavior associations. These observations extend prior longitudinal research back into prenatal brain development and raise exciting new ideas about the advent of risk and the ontogeny of early sex differences.
Many studies have identified changes in the brain associated with obsessive–compulsive disorder (OCD), but few have examined the relationship between genetic determinants of OCD and brain variation.
We present the first genome-wide investigation of overlapping genetic risk for OCD and genetic influences on subcortical brain structures.
Using single nucleotide polymorphism effect concordance analysis, we measured genetic overlap between the first genome-wide association study (GWAS) of OCD (1465 participants with OCD, 5557 controls) and recent GWASs of eight subcortical brain volumes (13 171 participants).
We found evidence of significant positive concordance between OCD risk variants and variants associated with greater nucleus accumbens and putamen volumes. When conditioning OCD risk variants on brain volume, variants influencing putamen, amygdala and thalamus volumes were associated with risk for OCD.
These results are consistent with current OCD neurocircuitry models. Further evidence will clarify the relationship between putamen volume and OCD risk, and the roles of the detected variants in this disorder.
Declaration of interest
The authors have declared that no competing interests exist.
Supersoft X-ray sources (hereafter SSS) are a class of luminous (bolometric luminosity ~ 1037 − 1038 erg s−1) objects with a characteristic radiation temperature of 30 to 60 eV (Hasinger 1994; Kahabka & Trümper 1996). The most popular model for SSS is that they are massive white dwarfs steadily burning nuclear fuel accreted from a more massive binary companion at a rate near or above the Eddington limit (van den Heuvel et al. 1992).
Research on close binary systems has continued at a high level during the past triennium, although the rate of growth is noticeably slower – probably reflecting the cutbacks in funds to which many of us are subject. There have also been changes of emphasis within the field, which are commented on in the pages that follow. These reflect both changing opportunities for observation and the natural development of the subject. In many areas, the time is ripe for a more critical look at ideas that previously seemed adequate.
We present an updated list of direct strong evidence in favour of kicks being imparted to newborn neutron stars. In particular we discuss the new cases of evidence resulting from recent observations of the X-ray binary Circinus X-1 and the newly discovered binary radio pulsar PSR J1141–6545. We conclude that the assumption that neutron stars receive a kick velocity at their formation is unavoidable (van den Heuvel & van Paradijs 1997).
This assumption explains a large variety of observations, ranging from direct observed properties of individual binary pulsars and Be/X-ray binaries to the observed birth rates and dynamical properties of the populations of LMXBs, binary recycled pulsars as well as the motion and distribution of single pulsars. Below we give an updated list in favour of kicks based on the compilation given by van den Heuvel & van Paradijs (1997) – see references therein for details.
We present first results of global VLBI astrometric pulsar parallax and proper motion measurements (phase-reference). The aim is to obtain information on pulsar motions and pulsar birthplaces. Proper motions could provide answers to questions like: How large are pulsar velocities at birth? How are these velocities produced and what is the final galactic pulsar distribution? Identification of birthplaces (with, e.g., an OB-association) provides information on the pulsar progenitor population (the fraction of pulsars born in binaries; the mass range of the progenitors etc.). We have a first epoch on three pulsars, selected on the basis of age (young < 3 Myr), flux density (relatively strong) and presence in the solar neighborhood (d < 3 kpc). Gating increases the SNR by typically a factor of 5.
Objectives: One of the most prominent features of schizophrenia is relatively lower general cognitive ability (GCA). An emerging approach to understanding the roots of variation in GCA relies on network properties of the brain. In this multi-center study, we determined global characteristics of brain networks using graph theory and related these to GCA in healthy controls and individuals with schizophrenia. Methods: Participants (N=116 controls, 80 patients with schizophrenia) were recruited from four sites. GCA was represented by the first principal component of a large battery of neurocognitive tests. Graph metrics were derived from diffusion-weighted imaging. Results: The global metrics of longer characteristic path length and reduced overall connectivity predicted lower GCA across groups, and group differences were noted for both variables. Measures of clustering, efficiency, and modularity did not differ across groups or predict GCA. Follow-up analyses investigated three topological types of connectivity—connections among high degree “rich club” nodes, “feeder” connections to these rich club nodes, and “local” connections not involving the rich club. Rich club and local connectivity predicted performance across groups. In a subsample (N=101 controls, 56 patients), a genetic measure reflecting mutation load, based on rare copy number deletions, was associated with longer characteristic path length. Conclusions: Results highlight the importance of characteristic path lengths and rich club connectivity for GCA and provide no evidence for group differences in the relationships between graph metrics and GCA. (JINS, 2016, 22, 240–249)
The expected final evolution of massive close binaries (CB) in case B is reviewed. Primary stars with masses ≳ 12–15 M⊙ are, after loosing most of their envelope by mass exchange, expected to explode as supernovae, leaving behind a neutron star or a black hole.
Conservative close binary evolution (i.e. without a major loss of mass and angular momentum from the system during the first stage of mass transfer) is expected to occur if the initial mass ratio q0 = M20/M10 is ≳ 0.3. In this case the primary star will be the less massive component when it explodes, and the system is almost never disrupted by the explosion. The explosion is followed by a long-lasting quiet stage (106–107 yr) when the system consists of a massive main-sequence star and an inactive compact companion. After the secondary has left the main-sequence and becomes a blue supergiant with a strong stellar wind, the system becomes a massive X-ray binary for a short while (2–5 × 104 yr).
The numbers of Wolf-Rayet binaries and massive X-ray binaries observed within 3 kpc of the Sun are in reasonable agreement with the numbers expected on the basis of conservative CB evolution, which implies that several thousands of massive main-sequence stars with a quiet compact companion should exist in the Galaxy. About a dozen of these systems must be present among the stars visible to the naked eye. During the second stage of mass exchange, large loss of mass and angular momentum from the system is expected, leading to a rapid shrinking of the orbit. The supernova explosion of the secondary will in most cases disrupt the system. If it remains bound, the final system will consist of two compact stars and may resemble the binary pulsar PSR 1913 + 16.
In systems with q0 ≲ 0.2–0.3 large mass loss from the system is expected during the first stage of mass exchange. The exploding primary will then be more massive than its unevolved companion and the first supernova explosion disrupts the system in most cases. In the rare cases that it remains bound, the system will have a large runaway velocity and, after a very long (108–109 yr) inactive stage evolves into a low-mass X-ray binary, possibly resembling Her X-1.
Smaller hippocampal volume has often been observed in patients with post-traumatic stress disorder (PTSD). However, there is no consensus whether this is a result of stress/trauma exposure, or constitutes a vulnerability factor for the development of PTSD. Second, it is unclear whether hippocampal volume normalizes with successful treatment of PTSD, or whether a smaller hippocampus is a risk factor for the persistence of PTSD.
Magnetic resonance imaging (MRI) scans and clinical interviews were collected from 47 war veterans with PTSD, 25 healthy war veterans (combat controls) and 25 healthy non-military controls. All veterans were scanned a second time with a 6- to 8-month interval, during which PTSD patients received trauma-focused therapy. Based on post-treatment PTSD symptoms, patients were divided into a PTSD group who was in remission (n = 22) and a group in whom PTSD symptoms persisted (n = 22). MRI data were analysed with Freesurfer.
Smaller left hippocampal volume was observed in PTSD patients compared with both control groups. Hippocampal volume of the combat controls did not differ from healthy controls. Second, pre- and post-treatment analyses of the PTSD patients and combat controls revealed reduced (left) hippocampal volume only in the persistent patients at both time points. Importantly, hippocampal volume did not change with treatment.
Our findings suggest that a smaller (left) hippocampus is not the result of stress/trauma exposure. Furthermore, hippocampal volume does not increase with successful treatment. Instead, we demonstrate for the first time that a smaller (left) hippocampus constitutes a risk factor for the persistence of PTSD.
Few studies have investigated the efficacy of repetitive transcranial magnetic stimulation (rTMS) treatment for negative symptoms of schizophrenia, reporting inconsistent results. We aimed to investigate whether 10 Hz stimulation of the bilateral dorsolateral prefrontal cortex during 3 weeks enhances treatment effects.
A multicenter double-blind randomized controlled trial was performed in 32 patients with schizophrenia or schizo-affective disorder, and moderate to severe negative symptoms [Positive and Negative Syndrome Scale (PANSS) negative subscale ⩾15]. Patients were randomized to a 3-week course of active or sham rTMS. Primary outcome was severity of negative symptoms as measured with the Scale for the Assessment of Negative Symptoms (SANS) and the PANSS negative symptom score. Secondary outcome measures included cognition, insight, quality of life and mood. Subjects were followed up at 4 weeks and at 3 months. For analysis of the data a mixed-effects linear model was used.
A significant improvement of the SANS in the active group compared with sham up to 3 months follow-up (p = 0.03) was found. The PANSS negative symptom scores did not show a significant change (p = 0.19). Of the cognitive tests, only one showed a significant improvement after rTMS as compared with sham. Finally, a significant change of insight was found with better scores in the treatment group.
Bilateral 10 Hz prefrontal rTMS reduced negative symptoms, as measured with the SANS. More studies are needed to investigate optimal parameters for rTMS, the cognitive effects and the neural basis.
Although cognitive subtypes have been suggested in schizophrenia patients, similar analyses have not been carried out in their non-affected siblings. Subtype classification may provide more insight into genetically driven variation in cognitive function. We investigated cognitive subtypes in siblings.
Cluster analyses were performed in 654 non-affected siblings, on a cognitive battery that included tests of attention, intellectual function and episodic memory. Resulting subtypes in the siblings were analyzed for cognitive, demographic and clinical characteristics and compared with those of their probands.
Three sibling subtypes of cognitive function were distinguished: ‘normal’, ‘mixed’ and ‘impaired’. Normal profile siblings (n = 192) were unimpaired on cognitive tests, in contrast to their proband (n = 184). Mixed profile siblings (n = 228) and their probands (n = 222) had a more similar performance pattern. Impaired profile siblings had poorer functional outcomes (n = 234) and their profile was almost identical to that of their proband (n = 223). Probands with cognitively impaired siblings could be distinguished from other schizophrenia patients by their own cognitive performance. They also had poorer clinical characteristics, including achievement of symptomatic remission.
Unaffected siblings of patients with schizophrenia are heterogeneous with respect to cognitive function. The poorer the cognitive profile of the sibling, the higher the level of correspondence with the proband. The sibling's cognitive subtype was predictive for disease course in the proband. Distinguishing cognitive subtypes of unaffected siblings may be of relevance for genetic studies.
Adolescence is a time for rapid growth that represents an opportunity to influence peak bone mass. Prebiotic agents, such as galacto-oligosaccharides (GOS), increase Ca absorption in animal models and postmenopausal women. The objectives of the present study were to investigate the dose–response relationship of GOS supplementation on Ca absorption during growth and to assess changes in colonic microbiota to better understand the mechanism by which GOS is acting. A total of thirty-one healthy adolescent girls aged 10–13 years consumed smoothie drinks twice daily with 0, 2·5 or 5 g GOS for three 3-week periods in a random order. Fractional Ca absorption was determined from urinary Ca excretion over 48 h at the end of each 3-week period using a dual stable isotope method. Faecal microbiota and bifidobacteria were assessed by PCR–denaturing gradient gel electrophoresis and quantitative PCR. Fractional Ca absorption after the 48 h treatment with control, 5 and 10 g GOS/d was 0·393 (sd 0·092), 0·444 (sd 0·086) and 0·419 (sd 0·099), respectively. Significant improvements in Ca absorption were seen with both low and high doses of GOS compared with the control (P< 0·02), but it was not a dose–response relationship. The increase in absorption was greatest in the urine collected after 24 h, which is consistent with lower gut absorption. Faecal bifidobacteria increased (control 10·89 (sd 13·86), 5 g GOS 22·80 (sd 15·74) and 10 g GOS 11·54 (sd 14·20)) with the GOS treatment (P< 0·03). The results suggest that daily consumption of 5 g GOS increases Ca absorption, which may be mediated by the gut microbiota, specifically bifidobacteria.
The need for symmetry and ordering objects related to a “just right”-feeling is a common symptom in Tourette's syndrome (TS) and resembles symmetry behavior in obsessive-compulsive disorder, but its pathophysiology is unknown. We used a symptom provocation paradigm to investigate the neural correlates of symmetry behavior in TS and hypothesized the involvement of frontal-striatal and limbic brain areas.
Pictures of asymmetrically and symmetrically arranged objects were presented in randomized blocks (4 blocks of each condition) to 14 patients with TS and 10 matched healthy controls (HC). A H215O positron emission tomography scan was acquired during each stimulus block, resulting in 8 scans per subject. After each scan, state anxiety and symmetry behavior (the urge to rearrange objects) were measured using a visual analogue scale.
During the asymmetry condition, TS patients showed increased regional cerebral blood flow (rCBF) in the anterior cingulate cortex, supplementary motor area, and inferior frontal cortex, whereas HC showed increased rCBF in the visual cortex, primary motor cortex, and dorsal prefrontal cortex. Symmetry ratings during provocation correlated positively with orbitofrontal activation in the TS group and sensorimotor activation in the HC group, and negatively with dorsal prefrontal activity in HC.
Results suggest that both motor and limbic circuits are involved in symmetry behavior in TS. Motor activity may relate to an urge to move or perform tics, and limbic activation may indicate that asymmetry stimuli are salient for TS patients. In contrast, symmetry provocation in HC resulted in activation of brain regions implicated in sensorimotor function and cognitive control.
Faecal microbial changes associated with ageing include reduced bifidobacteria numbers. These changes coincide with an increased risk of disease development. Prebiotics have been observed to increase bifidobacteria numbers within humans. The present study aimed to determine if prebiotic galacto-oligosaccharides (GOS) could benefit a population of men and women of 50 years and above, through modulation of faecal microbiota, fermentation characteristics and faecal water genotoxicity. A total of thirty-seven volunteers completed this randomised, double-blind, placebo-controlled crossover trial. The treatments – juice containing 4 g GOS and placebo – were consumed twice daily for 3 weeks, preceded by 3-week washout periods. To study the effect of GOS on different large bowel regions, three-stage continuous culture systems were conducted in parallel using faecal inocula from three volunteers. Faecal samples were microbially enumerated by quantitative PCR. In vivo, following GOS intervention, bifidobacteria were significantly more compared to post-placebo (P = 0·02). Accordingly, GOS supplementation had a bifidogenic effect in all in vitro system vessels. Furthermore, in vessel 1 (similar to the proximal colon), GOS fermentation led to more lactobacilli and increased butyrate. No changes in faecal water genotoxicity were observed. To conclude, GOS supplementation significantly increased bifidobacteria numbers in vivo and in vitro. Increased butyrate production and elevated bifidobacteria numbers may constitute beneficial modulation of the gut microbiota in a maturing population.