348 research outputs found
Winning versus losing during gambling and its neural correlates
Humans often make decisions which maximize an internal utility function. For
example, humans often maximize their expected reward when gambling and this is
considered as a "rational" decision. However, humans tend to change their
betting strategies depending on how they "feel". If someone has experienced a
losing streak, they may "feel" that they are more likely to win on the next
hand even though the odds of the game have not changed. That is, their
decisions are driven by their emotional state. In this paper, we investigate
how the human brain responds to wins and losses during gambling. Using a
combination of local field potential recordings in human subjects performing a
financial decision-making task, spectral analyses, and non-parametric cluster
statistics, we investigated whether neural responses in different cognitive and
limbic brain areas differ between wins and losses after decisions are made. In
eleven subjects, the neural activity modulated significantly between win and
loss trials in one brain region: the anterior insula (). In particular,
gamma activity (30-70 Hz) increased in the anterior insula when subjects just
realized that they won. Modulation of metabolic activity in the anterior insula
has been observed previously in functional magnetic resonance imaging studies
during decision making and when emotions are elicited. However, our study is
able to characterize temporal dynamics of electrical activity in this brain
region at the millisecond resolution while decisions are made and after
outcomes are revealed
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An injectable bone marrow-like scaffold enhances T cell immunity after hematopoietic stem cell transplantation.
Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for multiple disorders, but deficiency and dysregulation of T cells limit its utility. Here we report a biomaterial-based scaffold that mimics features of T cell lymphopoiesis in the bone marrow. The bone marrow cryogel (BMC) releases bone morphogenetic protein-2 to recruit stromal cells and presents the Notch ligand Delta-like ligand-4 to facilitate T cell lineage specification of mouse and human hematopoietic progenitor cells. BMCs subcutaneously injected in mice at the time of HSCT enhanced T cell progenitor seeding of the thymus, T cell neogenesis and diversification of the T cell receptor repertoire. Peripheral T cell reconstitution increased ~6-fold in mouse HSCT and ~2-fold in human xenogeneic HSCT. Furthermore, BMCs promoted donor CD4+ regulatory T cell generation and improved survival after allogeneic HSCT. In comparison to adoptive transfer of T cell progenitors, BMCs increased donor chimerism, T cell generation and antigen-specific T cell responses to vaccination. BMCs may provide an off-the-shelf approach for enhancing T cell regeneration and mitigating graft-versus-host disease in HSCT
Attention Drives Synchronization of Alpha and Beta Rhythms between Right Inferior Frontal and Primary Sensory Neocortex
The right inferior frontal cortex (rIFC) is specifically associated with attentional control via the inhibition of behaviorally irrelevant stimuli and motor responses. Similarly, recent evidence has shown that alpha (7–14 Hz) and beta (15–29 Hz) oscillations in primary sensory neocortical areas are enhanced in the representation of non-attended stimuli, leading to the hypothesis that allocation of these rhythms plays an active role in optimal inattention. Here, we tested the hypothesis that selective synchronization between rIFC and primary sensory neocortex occurs in these frequency bands during inattention. We used magnetoencephalography to investigate phase synchrony between primary somatosensory (SI) and rIFC regions during a cued-attention tactile detection task that required suppression of response to uncertain distractor stimuli. Attentional modulation of synchrony between SI and rIFC was found in both the alpha and beta frequency bands. This synchrony manifested as an increase in the alpha-band early after cue between non-attended SI representations and rIFC, and as a subsequent increase in beta-band synchrony closer to stimulus processing. Differences in phase synchrony were not found in several proximal control regions. These results are the first to reveal distinct interactions between primary sensory cortex and rIFC in humans and suggest that synchrony between rIFC and primary sensory representations plays a role in the inhibition of irrelevant sensory stimuli and motor responses.National Institutes of Health (U.S.) (Grant P41RR14075)National Institutes of Health (U.S.) (Grant K25MH072941)National Institutes of Health (U.S.) (Grant K01AT003459)National Institutes of Health (U.S.) (Grant K24AT004095)National Institutes of Health (U.S.) (Grant RO1-NS045130-01)National Institutes of Health (U.S.) (Grant T32GM007484)National Science Foundation (U.S.) (Grant 0316933)National Science Foundation (U.S.). Graduate Research Fellowship Program (Grant DGE-1147470
The gravitational-wave background null hypothesis: Characterizing noise in millisecond pulsar arrival times with the Parkes Pulsar Timing Array
The noise in millisecond pulsar (MSP) timing data can include contributions
from observing instruments, the interstellar medium, the solar wind, solar
system ephemeris errors, and the pulsars themselves. The noise environment must
be accurately characterized in order to form the null hypothesis from which
signal models can be compared, including the signature induced by
nanohertz-frequency gravitational waves (GWs). Here we describe the noise
models developed for each of the MSPs in the Parkes Pulsar Timing Array (PPTA)
third data release, which have been used as the basis of a search for the
isotropic stochastic GW background. We model pulsar spin noise, dispersion
measure variations, scattering variations, events in the pulsar magnetospheres,
solar wind variability, and instrumental effects. We also search for new timing
model parameters and detected Shapiro delays in PSR~J06143329 and
PSR~J19025105. The noise and timing models are validated by testing the
normalized and whitened timing residuals for Gaussianity and residual
correlations with time. We demonstrate that the choice of noise models
significantly affects the inferred properties of a common-spectrum process.
Using our detailed models, the recovered common-spectrum noise in the PPTA is
consistent with a power law with a spectral index of , the value
predicted for a stochastic GW background from a population of supermassive
black hole binaries driven solely by GW emission.Comment: 18 pages, 10 figures. Accepted for publication in ApJ
Inhibition of sarcolemmal FAT/CD36 by sulfo-N-succinimidyl oleate rapidly corrects metabolism and restores function in the diabetic heart following hypoxia/reoxygenation.
AIMS: The type 2 diabetic heart oxidizes more fat and less glucose, which can impair metabolic flexibility and function. Increased sarcolemmal fatty acid translocase (FAT/CD36) imports more fatty acid into the diabetic myocardium, feeding increased fatty acid oxidation and elevated lipid deposition. Unlike other metabolic modulators that target mitochondrial fatty acid oxidation, we proposed that pharmacologically inhibiting fatty acid uptake, as the primary step in the pathway, would provide an alternative mechanism to rebalance metabolism and prevent lipid accumulation following hypoxic stress. METHODS AND RESULTS: Hearts from type 2 diabetic and control male Wistar rats were perfused in normoxia, hypoxia and reoxygenation, with the FAT/CD36 inhibitor sulfo-N-succinimidyl oleate (SSO) infused 4 min before hypoxia. SSO infusion into diabetic hearts decreased the fatty acid oxidation rate by 29% and myocardial triglyceride concentration by 48% compared with untreated diabetic hearts, restoring fatty acid metabolism to control levels following hypoxia-reoxygenation. SSO infusion increased the glycolytic rate by 46% in diabetic hearts during hypoxia, increased pyruvate dehydrogenase activity by 53% and decreased lactate efflux rate by 56% compared with untreated diabetic hearts during reoxygenation. In addition, SSO treatment of diabetic hearts increased intermediates within the second span of the Krebs cycle, namely fumarate, oxaloacetate, and the FAD total pool. The cardiac dysfunction in diabetic hearts following decreased oxygen availability was prevented by SSO-infusion prior to the hypoxic stress. Infusing SSO into diabetic hearts increased rate pressure product by 60% during hypoxia and by 32% following reoxygenation, restoring function to control levels. CONCLUSIONS: Diabetic hearts have limited metabolic flexibility and cardiac dysfunction when stressed, which can be rapidly rectified by reducing fatty acid uptake with the FAT/CD36 inhibitor, SSO. This novel therapeutic approach not only reduces fat oxidation but also lipotoxicity, by targeting the primary step in the fatty acid metabolism pathway
Search for an isotropic gravitational-wave background with the Parkes Pulsar Timing Array
Pulsar timing arrays aim to detect nanohertz-frequency gravitational waves
(GWs). A background of GWs modulates pulsar arrival times and manifests as a
stochastic process, common to all pulsars, with a signature spatial
correlation. Here we describe a search for an isotropic stochastic
gravitational-wave background (GWB) using observations of 30 millisecond
pulsars from the third data release of the Parkes Pulsar Timing Array (PPTA),
which spans 18 years. Using current Bayesian inference techniques we recover
and characterize a common-spectrum noise process. Represented as a strain
spectrum , we measure and respectively (median and 68%
credible interval). For a spectral index of , corresponding to an
isotropic background of GWs radiated by inspiraling supermassive black hole
binaries, we recover an amplitude of .
However, we demonstrate that the apparent signal strength is time-dependent, as
the first half of our data set can be used to place an upper limit on that
is in tension with the inferred common-spectrum amplitude using the complete
data set. We search for spatial correlations in the observations by
hierarchically analyzing individual pulsar pairs, which also allows for
significance validation through randomizing pulsar positions on the sky. For a
process with , we measure spatial correlations consistent with a
GWB, with an estimated false-alarm probability of (approx.
). The long timing baselines of the PPTA and the access to southern
pulsars will continue to play an important role in the International Pulsar
Timing Array.Comment: 19 pages, 10 figures, Accepted for publication in ApJ
The state of the Martian climate
60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
A population of gamma-ray emitting globular clusters seen with the Fermi Large Area Telescope
Globular clusters with their large populations of millisecond pulsars (MSPs)
are believed to be potential emitters of high-energy gamma-ray emission. Our
goal is to constrain the millisecond pulsar populations in globular clusters
from analysis of gamma-ray observations. We use 546 days of continuous
sky-survey observations obtained with the Large Area Telescope aboard the Fermi
Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular
clusters. Steady point-like high-energy gamma-ray emission has been
significantly detected towards 8 globular clusters. Five of them (47 Tucanae,
Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices and clear evidence for an exponential cut-off in the range
1.0-2.6 GeV, which is the characteristic signature of magnetospheric emission
from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral
indices , however the presence of an exponential cut-off
can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC
6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral
properties. From the observed gamma-ray luminosities, we estimate the total
number of MSPs that is expected to be present in these globular clusters. We
show that our estimates of the MSP population correlate with the stellar
encounter rate and we estimate 2600-4700 MSPs in Galactic globular clusters,
commensurate with previous estimates. The observation of high-energy gamma-ray
emission from a globular cluster thus provides a reliable independent method to
assess their millisecond pulsar populations that can be used to make
constraints on the original neutron star X-ray binary population, essential for
understanding the importance of binary systems in slowing the inevitable core
collapse of globular clusters.Comment: Accepted for publication in A&A. Corresponding authors: J.
Kn\"odlseder, N. Webb, B. Pancraz
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