164 research outputs found

    Preliminary evidence for human globus pallidus pars interna neurons signaling reward and sensory stimuli.

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    The globus pallidus pars interna (GPi) is a component of the basal ganglia, a network of subcortical nuclei that process motor, associative, and limbic information. While non-human primate studies have suggested a role for the GPi in non-motor functions, there have been no single-unit studies of non-motor electrophysiological behavior of human GPi neurons. We therefore sought to extend these findings by collecting single-unit recordings from awake patients during functional stereotactic neurosurgery targeting the GPi for deep brain stimulation. To assess cellular responses to non-motor information, patients performed a reward task where virtual money could be won, lost, or neither, depending on their performance while cellular activity was monitored. Changes in the firing rates of isolated GPi neurons after the presentation of reward-related stimuli were compared between different reward contingencies (win, loss, null). We observed neurons that modulated their firing rate significantly to the presentation of reward-related stimuli. We furthermore found neurons that responded to visual-stimuli more broadly. This is the first single-unit evidence of human GPi neurons carrying non-motor information. These results are broadly consistent with previous findings in the animal literature and suggest non-motor information may be represented in the single-unit activity of human GPi neurons.NAH is supported by a Unilever/Lipton Graduate Fellowship in Neuroscience and a University of Toronto Fellowship. WDH is supported by a CIHR operating grant (98006). VV is a Wellcome Trust (WT) intermediate Clinical Fellow (WT093705MA).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroscience.2016.04.02

    MIGHTEE: multi-wavelength counterparts in the COSMOS field

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    In this paper, we combine the Early Science radio continuum data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey, with optical and near-infrared data and release the cross-matched catalogues. The radio data used in this work covers 0.86 deg2 of the COSMOS field, reaches a thermal noise of 1.7 μJy beam−1 and contains 6102 radio components. We visually inspect and cross-match the radio sample with optical and near-infrared data from the Hyper Suprime-Cam (HSC) and UltraVISTA surveys. This allows the properties of active galactic nuclei and star-forming populations of galaxies to be probed out to z ≈ 5. Additionally, we use the likelihood ratio method to automatically cross-match the radio and optical catalogues and compare this to the visually cross-matched catalogue. We find that 94 per cent of our radio source catalogue can be matched with this method, with a reliability of 95 per cent. We proceed to show that visual classification will still remain an essential process for the cross-matching of complex and extended radio sources. In the near future, the MIGHTEE survey will be expanded in area to cover a total of ∼20 deg2; thus the combination of automated and visual identification will be critical. We compare the redshift distribution of SFG and AGN to the SKADS and T-RECS simulations and find more AGN than predicted at z ∼ 1

    MeerKLASS: MeerKAT Large Area Synoptic Survey

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    We discuss the ground-breaking science that will be possible with a wide area survey, using the MeerKAT telescope, known as MeerKLASS (MeerKAT Large Area Synoptic Survey). The current specifications of MeerKAT make it a great fit for science applications that require large survey speeds but not necessarily high angular resolutions. In particular, for cosmology, a large survey over ∼4,000 deg2\sim 4,000 \, {\rm deg}^2 for ∼4,000\sim 4,000 hours will potentially provide the first ever measurements of the baryon acoustic oscillations using the 21cm intensity mapping technique, with enough accuracy to impose constraints on the nature of dark energy. The combination with multi-wavelength data will give unique additional information, such as exquisite constraints on primordial non-Gaussianity using the multi-tracer technique, as well as a better handle on foregrounds and systematics. Such a wide survey with MeerKAT is also a great match for HI galaxy studies, providing unrivalled statistics in the pre-SKA era for galaxies resolved in the HI emission line beyond local structures at z > 0.01. It will also produce a large continuum galaxy sample down to a depth of about 5\,μ\muJy in L-band, which is quite unique over such large areas and will allow studies of the large-scale structure of the Universe out to high redshifts, complementing the galaxy HI survey to form a transformational multi-wavelength approach to study galaxy dynamics and evolution. Finally, the same survey will supply unique information for a range of other science applications, including a large statistical investigation of galaxy clusters as well as produce a rotation measure map across a huge swathe of the sky. The MeerKLASS survey will be a crucial step on the road to using SKA1-MID for cosmological applications and other commensal surveys, as described in the top priority SKA key science projects (abridged).Comment: Larger version of the paper submitted to the Proceedings of Science, "MeerKAT Science: On the Pathway to the SKA", Stellenbosch, 25-27 May 201

    Middle and Late Pleistocene environmental history of the Marsworth area, south-central England

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    To elucidate the Middle and Late Pleistocene environmental history of south-central England, we report the stratigraphy, sedimentology, palaeoecology and geochronology of some deposits near the foot of the Chiltern Hills scarp at Marsworth, Buckinghamshire. The Marsworth site is important because its sedimentary sequences contain a rich record of warm stages and cold stages, and it lies close to the Anglian glacial limit. Critical to its history are the origin and age of a brown pebbly silty clay (diamicton) previously interpreted as weathered till. The deposits described infill a river channel incised into chalk bedrock. They comprise clayey, silty and gravelly sediments, many containing locally derived chalk and some with molluscan, ostracod and vertebrate remains. Most of the deposits are readily attributed to periglacial and fluvial processes, and some are dated by optically stimulated luminescence to Marine Isotope Stage (MIS) 6. Although our sedimentological data do not discriminate between a glacial or periglacial interpretation of the diamicton, amino-acid dating of three molluscan taxa from beneath it indicates that it is younger than MIS 9 and older than MIS 5e. This makes a glacial interpretation unlikely, and we interpret the diamicton as a periglacial slope deposit. The Pleistocene history reconstructed for Marsworth identifies four key elements: (1) Anglian glaciation during MIS 12 closely approached Marsworth, introducing far-travelled pebbles such as Rhaxella chert and possibly some fine sand minerals into the area. (2) Interglacial environments inferred from fluvial sediments during MIS 7 varied from fully interglacial conditions during sub-stages 7e and 7c, cool temperate conditions during sub-stage 7b or 7a, temperate conditions similar to those today in central England towards the end of the interglacial, and cool temperate conditions during sub-stage 7a. (3) Periglacial activity during MIS 6 involved thermal contraction cracking, permafrost development, fracturing of chalk bedrock, fluvial activity, slopewash, mass movement and deposition of loess and coversand. (4) Fully interglacial conditions during sub-stage 5e led to renewed fluvial activity, soil formation and acidic weathering

    Genetic and shared couple environmental contributions to smoking and alcohol use in the UK population

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    Alcohol use and smoking are leading causes of death and disability worldwide. Both genetic and environmental factors have been shown to influence individual differences in the use of these substances. In the present study we tested whether genetic factors, modelled alongside common family environment, explained phenotypic variance in alcohol use and smoking behaviour in the Generation Scotland (GS) family sample of up to 19,377 individuals. SNP and pedigree-associated effects combined explained between 18 and 41% of the variance in substance use. Shared couple effects explained a significant amount of variance across all substance use traits, particularly alcohol intake, for which 38% of the phenotypic variance was explained. We tested whether the within-couple substance use associations were due to assortative mating by testing the association between partner polygenic risk scores in 34,987 couple pairs from the UK Biobank (UKB). No significant association between partner polygenic risk scores were observed. Associations between an individual's alcohol PRS (b = 0.05, S.E. = 0.006, p < 2 × 10 ) and smoking status PRS (b = 0.05, S.E. = 0.005, p < 2 × 10 ) were found with their partner's phenotype. In support of this, G carriers of a functional ADH1B polymorphism (rs1229984), known to be associated with greater alcohol intake, were found to consume less alcohol if they had a partner who carried an A allele at this SNP. Together these results show that the shared couple environment contributes significantly to patterns of substance use. It is unclear whether this is due to shared environmental factors, assortative mating, or indirect genetic effects. Future studies would benefit from longitudinal data and larger sample sizes to assess this further

    Volunteer Bias in Recruitment, Retention, and Blood Sample Donation in a Randomised Controlled Trial Involving Mothers and Their Children at Six Months and Two Years: A Longitudinal Analysis

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    BACKGROUND: The vulnerability of clinical trials to volunteer bias is under-reported. Volunteer bias is systematic error due to differences between those who choose to participate in studies and those who do not. METHODS AND RESULTS: This paper extends the applications of the concept of volunteer bias by using data from a trial of probiotic supplementation for childhood atopy in healthy dyads to explore 1) differences between a) trial participants and aggregated data from publicly available databases b) participants and non-participants as the trial progressed 2) impact on trial findings of weighting data according to deprivation (Townsend) fifths in the sample and target populations. 1) a) Recruits (n = 454) were less deprived than the target population, matched for area of residence and delivery dates (n = 6,893) (mean [SD] deprivation scores 0.09[4.21] and 0.79[4.08], t = 3.44, df = 511, p<0.001). b) i) As the trial progressed, representation of the most deprived decreased. These participants and smokers were less likely to be retained at 6 months (n = 430[95%]) (OR 0.29,0.13-0.67 and 0.20,0.09-0.46), and 2 years (n = 380[84%]) (aOR 0.68,0.50-0.93 and 0.55,0.28-1.09), and consent to infant blood sample donation (n = 220[48%]) (aOR 0.72,0.57-0.92 and 0.43,0.22-0.83). ii) Mothers interested in probiotics or research or reporting infants' adverse events or rashes were more likely to attend research clinics and consent to skin-prick testing. Mothers participating to help children were more likely to consent to infant blood sample donation. 2) In one trial outcome, atopic eczema, the intervention had a positive effect only in the over-represented, least deprived group. Here, data weighting attenuated risk reduction from 6.9%(0.9-13.1%) to 4.6%(-1.4-+10.5%), and OR from 0.40(0.18-0.91) to 0.56(0.26-1.21). Other findings were unchanged. CONCLUSIONS: Potential for volunteer bias intensified during the trial, due to non-participation of the most deprived and smokers. However, these were not the only predictors of non-participation. Data weighting quantified volunteer bias and modified one important trial outcome. TRIAL REGISTRATION: This randomised, double blind, parallel group, placebo controlled trial is registered with the International Standard Randomised Controlled Trials Register, Number (ISRCTN) 26287422. Registered title: Probiotics in the prevention of atopy in infants and children

    Construction of a Global Pain Systems Network Highlights Phospholipid Signaling as a Regulator of Heat Nociception

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    The ability to perceive noxious stimuli is critical for an animal's survival in the face of environmental danger, and thus pain perception is likely to be under stringent evolutionary pressure. Using a neuronal-specific RNAi knock-down strategy in adult Drosophila, we recently completed a genome-wide functional annotation of heat nociception that allowed us to identify α2δ3 as a novel pain gene. Here we report construction of an evolutionary-conserved, system-level, global molecular pain network map. Our systems map is markedly enriched for multiple genes associated with human pain and predicts a plethora of novel candidate pain pathways. One central node of this pain network is phospholipid signaling, which has been implicated before in pain processing. To further investigate the role of phospholipid signaling in mammalian heat pain perception, we analysed the phenotype of PIP5Kα and PI3Kγ mutant mice. Intriguingly, both of these mice exhibit pronounced hypersensitivity to noxious heat and capsaicin-induced pain, which directly mapped through PI3Kγ kinase-dead knock-in mice to PI3Kγ lipid kinase activity. Using single primary sensory neuron recording, PI3Kγ function was mechanistically linked to a negative regulation of TRPV1 channel transduction. Our data provide a systems map for heat nociception and reinforces the extraordinary conservation of molecular mechanisms of nociception across different species. © 2012 Neely et al
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