40 research outputs found

    Fronto-striatal organization: Defining functional and microstructural substrates of behavioural flexibility.

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    Discrete yet overlapping frontal-striatal circuits mediate broadly dissociable cognitive and behavioural processes. Using a recently developed multi-echo resting-state functional MRI (magnetic resonance imaging) sequence with greatly enhanced signal compared to noise ratios, we map frontal cortical functional projections to the striatum and striatal projections through the direct and indirect basal ganglia circuit. We demonstrate distinct limbic (ventromedial prefrontal regions, ventral striatum - VS, ventral tegmental area - VTA), motor (supplementary motor areas - SMAs, putamen, substantia nigra) and cognitive (lateral prefrontal and caudate) functional connectivity. We confirm the functional nature of the cortico-striatal connections, demonstrating correlates of well-established goal-directed behaviour (involving medial orbitofrontal cortex - mOFC and VS), probabilistic reversal learning (lateral orbitofrontal cortex - lOFC and VS) and attentional shifting (dorsolateral prefrontal cortex - dlPFC and VS) while assessing habitual model-free (SMA and putamen) behaviours on an exploratory basis. We further use neurite orientation dispersion and density imaging (NODDI) to show that more goal-directed model-based learning (MBc) is also associated with higher mOFC neurite density and habitual model-free learning (MFc) implicates neurite complexity in the putamen. This data highlights similarities between a computational account of MFc and conventional measures of habit learning. We highlight the intrinsic functional and structural architecture of parallel systems of behavioural control.VV and NAH are Wellcome Trust (WT) intermediate Clinical Fellows. LM is in receipt of an MRC studentship. The BCNI is supported by a WT and MRC grant. ETB is employed part-time by the University of Cambridge and part-time by GSK PLC and is a shareholder of GSK. TWR is a consultant for Cambridge Cognition, Eli Lilly, GSK, Merck, Sharpe and Dohme, Lundbeck, Teva and Shire Pharmaceuticals. He is or has been in receipt of research grants from Lundbeck, Eli Lilly and GSK and is an editor for Springer-Verlag (Psychopharmacology). The remaining authors declare no competing financial interests. The study was funded by the Wellcome Trust Fellowship grant for VV (093705/Z/10/Z) and Cambridge NIHR Biomedical Research Centre.This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.cortex.2015.11.00

    Search for Gravitational Waves from Scorpius X-1 in LIGO O3 Data With Corrected Orbital Ephemeris

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    Improved observational constraints on the orbital parameters of the low-mass X-ray binary Scorpius~X-1 were recently published in Killestein et al (2023). In the process, errors were corrected in previous orbital ephemerides, which have been used in searches for continuous gravitational waves from Sco~X-1 using data from the Advanced LIGO detectors. We present the results of a re-analysis of LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo using a model-based cross-correlation search. The corrected region of parameter space, which was not covered by previous searches, was about 1/3 as large as the region searched in the original O3 analysis, reducing the required computing time. We have confirmed that no detectable signal is present over a range of gravitational-wave frequencies from 25Hz25\textrm{Hz} to 1600Hz1600\textrm{Hz}, analogous to the null result of Abbott et al (2022). Our search sensitivity is comparable to that of Abbott et al (2022), who set upper limits corresponding, between 100Hz100\textrm{Hz} and 200Hz200\textrm{Hz}, to an amplitude h0h_0 of about 102510^{-25} when marginalized isotropically over the unknown inclination angle of the neutron star's rotation axis, or less than 4×10264\times 10^{-26} assuming the optimal orientation.Comment: 8 pages, 3 figures, 2 tables. Typeset with AASTeX 6.3.1. Accepted for publication in The Astrophysical Journal. arXiv admin note: text overlap with arXiv:2209.0286

    Stochastic Background Search Correlating ALLEGRO with LIGO Engineering Data

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    We describe the role of correlation measurements between the LIGO interferometer in Livingston, LA, and the ALLEGRO resonant bar detector in Baton Rouge, LA, in searches for a stochastic background of gravitational waves. Such measurements provide a valuable complement to correlations between interferometers at the two LIGO sites, since they are sensitive in a different, higher, frequency band. Additionally, the variable orientation of the ALLEGRO detector provides a means to distinguish gravitational wave correlations from correlated environmental noise. We describe the analysis underway to set a limit on the strength of a stochastic background at frequencies near 900 Hz using ALLEGRO data and data from LIGO's E7 Engineering Run.Comment: 8 pages, 2 encapsulated PostScript figures, uses IOP class files, submitted to the proceedings of the 7th Gravitational Wave Data Analysis Workshop (which will be published in Classical and Quantum Gravity

    Fluphenazine-induced acute and tardive dyskinesias in monkeys

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    Five Cebus apella monkeys were treated with biweekly injections of fluphenazine enanthate (0.1–3.2 mg/kg IM). Three of these completed 1 full year of treatment, one injured its leg after 6 months of treatment and was killed, and another died of unknown causes after 9 months of treatment. All monkeys displayed abnormal movements corresponding to the early appearing extrapyramidal symptoms of neuroleptic-treated patients. These consisted initially of slowing or absence of volitional movement, trembling of the hands, trembling of the entire body, and general drowsy behavior. As treatment progessed, a variety of abnormal postures and movements appeared after each injection that were not exacerbated by drug withdrawal and, as tested at the end of the year, could be abolished or prevented with benztropine mesylate (0.2–0.5 mg/kg IM). The three monkeys that completed 1 year of treatment with fluphenazine were then withdrawn from the drug. After withdrawal, all three developed movements similar in appearance to those of patients with tardive dyskinesia (TD). Reinstitution of fluphenazine treatment, as tested in one monkey, abolished all movements resembling TD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46432/1/213_2004_Article_BF00555204.pd

    Upper limits on the strength of periodic gravitational waves from PSR J1939+2134

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    The first science run of the LIGO and GEO gravitational wave detectors presented the opportunity to test methods of searching for gravitational waves from known pulsars. Here we present new direct upper limits on the strength of waves from the pulsar PSR J1939+2134 using two independent analysis methods, one in the frequency domain using frequentist statistics and one in the time domain using Bayesian inference. Both methods show that the strain amplitude at Earth from this pulsar is less than a few times 102210^{-22}.Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 200

    Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers

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    We study frequency dependent (FD) input-output schemes for signal-recycling interferometers, the baseline design of Advanced LIGO and the current configuration of GEO 600. Complementary to a recent proposal by Harms et al. to use FD input squeezing and ordinary homodyne detection, we explore a scheme which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are sub-optimal among all possible input-output schemes, provide a global noise suppression by the power squeeze factor, while being realizable by using detuned Fabry-Perot cavities as input/output filters. At high frequencies, the two schemes are shown to be equivalent, while at low frequencies our scheme gives better performance than that of Harms et al., and is nearly fully optimal. We then study the sensitivity improvement achievable by these schemes in Advanced LIGO era (with 30-m filter cavities and current estimates of filter-mirror losses and thermal noise), for neutron star binary inspirals, and for narrowband GW sources such as low-mass X-ray binaries and known radio pulsars. Optical losses are shown to be a major obstacle for the actual implementation of these techniques in Advanced LIGO. On time scales of third-generation interferometers, like EURO/LIGO-III (~2012), with kilometer-scale filter cavities, a signal-recycling interferometer with the FD readout scheme explored in this paper can have performances comparable to existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi

    ITPKC Single Nucleotide Polymorphism Associated with the Kawasaki Disease in a Taiwanese Population

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    Kawasaki disease (KD) is characterized by systemic vasculitis with unknown etiology. Previous studies from Japan indicated that a gene polymorphism of ITPKC (rs28493229) is responsible for susceptibility to KD. We collected DNA samples from 1,531 Taiwanese subjects (341 KD patients and 1,190 controls) for genotyping ITPKC. In this study, no significant association was noted for the ITPKC polymorphism (rs28493229) between the controls and KD patients, although the CC genotype was overrepresented. We further combined our data with previously published case/control KD studies in the Taiwanese population and performed a meta-analysis. A significant association between rs28493229 and KD was found (Odds Ratio:1.36, 95% Confidence Interval 1.12–1.66). Importantly, a significant association was obtained between rs28493229 and KD patients with aneurysm formation (P = 0.001, under the recessive model). Taken together, our results indicated that C-allele of ITPKC SNP rs28493229 is associated with the susceptibility and aneurysm formation in KD patients in a Taiwanese population
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