The right temporo-parietal junction (TPJ) is widely considered as part of a network that reorients attention to task-relevant, but currently unattended stimuli (Corbetta and Shulman, 2002). Despite ...the prevalence of this theory in cognitive neuroscience, there is little direct evidence for the principal hypothesis that TPJ sends an early reorientation signal that "circuit breaks" attentional processing in regions of the dorsal attentional network (e.g., the frontal eye fields) or is completely right lateralized during attentional processing. In this review, we examine both functional neuroimaging work on TPJ in the attentional literature as well as anatomical findings. We first critically evaluate the idea that TPJ reorients attention and is right lateralized; we then suggest that TPJ signals might rather reflect post-perceptual processes involved in contextual updating and adjustments of top-down expectations; and then finally discuss how these ideas relate to the electrophysiological (P300) literature, and to TPJ findings in other cognitive and social domains. We conclude that while much work is needed to define the computational functions of regions encapsulated as TPJ, there is now substantial evidence that it is not specialized for stimulus-driven attentional reorienting.
Much is known about the mechanisms by which attention is focused to facilitate perception, but little is known about what happens to attention after perception of the attended object is complete. One ...possibility is that the focus of attention passively fades. A second possibility is that attention is actively terminated after the completion of perception so that the brain can be prepared for the next target. The present study investigated this issue with event-related potentials in humans, focusing on the N2pc component (a neural measure of attentional deployment) and the Pd component (a neural measure of attentional suppression). We found that active suppression occurred both to prevent the allocation of attention to known distractors and to terminate attention after the perception of an attended object was complete. In addition, the neural measure of active suppression was correlated with a behavioral measure of trial-to-trial variations in the allocation of attention. Active suppression therefore appears to be a general-purpose mechanism that both prevents and terminates the allocation of attention.
We revisit the classical relation between the strangeness content of the nucleon, the pion–nucleon sigma term and the SU(3)F breaking of the baryon masses in the context of Lorentz covariant chiral ...perturbation theory with explicit decuplet-baryon resonance fields. We find that a value of the pion–nucleon sigma term of ∼60 MeV is not necessarily at odds with a small strangeness content of the nucleon, in line with the fulfillment of the OZI rule. Moreover, this value is indeed favored by our next-to-leading order calculation. We compare our results with earlier ones and discuss the convergence of the chiral series as well as the uncertainties of chiral approaches to the determination of the sigma terms.
Attentional Mechanisms of Distractor Suppression Geng, Joy J.
Current directions in psychological science : a journal of the American Psychological Society,
04/2014, Letnik:
23, Številka:
2
Journal Article
Recenzirano
The ability to suppress distractors is critical for the successful completion of goal-oriented behaviors. This is particularly true for everyday behaviors that take time to accomplish and are ...frequently interrupted by unpredicted events (e.g., spotting a sale on a favorite drink while searching a grocery store for an apple). For one to continue with the intended goal, attention to the distractor must be reactively suppressed (i.e., terminated) so that the goal-oriented behavior may resume. Such reactive suppression can be contrasted with a proactive mechanism that anticipates the appearance of a distractor and suppresses related sensory processing in advance. In this review, I consider three aspects of distractor suppression: (a) the distinction between proactive and reactive mechanisms, (b) the conditions under which reactive distractor rejection can be rapid, and (c) the neural and cognitive processes necessary for controlling proactive and reactive distractor suppression.
MicroRNAs (miRNAs) play important roles in the pathogenesis of cardiovascular diseases. Circulating miRNAs were recently identified as biomarkers for various physiological and pathological ...conditions. In this study, we aimed to identify the circulating miRNA fingerprint of vulnerable coronary artery disease (CAD) and explore its potential as a novel biomarker for this disease.
The Taqman low-density miRNA array and coexpression network analyses were used to identify distinct miRNA expression profiles in the plasma of patients with typical unstable angina (UA) and angiographically documented CAD (UA group, n = 13) compared to individuals with non-cardiac chest pain (control group, n = 13). Significantly elevated expression levels of miR-106b/25 cluster, miR-17/92a cluster, miR-21/590-5p family, miR-126*, and miR-451 were observed in UA patients compared to controls. These findings were validated by real-time PCR in another 45 UA patients, 31 stable angina patients, and 37 controls. In addition, miR-106b, miR-25, miR-92a, miR-21, miR-590-5p, miR-126* and miR-451 were upregulated in microparticles (MPs) isolated from the plasma of UA patients (n = 5) compared to controls (n = 5). Using flow cytometry and immunolabeling, we further found that Annexin V(+) MPs were increased in the plasma samples of UA patients compared to controls, and the majority of the increased MPs in plasma were shown to be Annexin V(+) CD31(+) MPs. The findings suggest that Annexin V(+) CD31(+) MPs may contribute to the elevated expression of the selected miRNAs in the circulation of patients with vulnerable CAD.
The circulating miRNA signature, consisting of the miR-106b/25 cluster, miR-17/92a cluster, miR-21/590-5p family, miR-126* and miR-451, may be used as a novel biomarker for vulnerable CAD.
Chinese Clinical Trial Register, ChiCTR-OCH-12002349.
Elvin Hsing Geng and colleagues discuss mechanism mapping and its utility in conceptualizing and understanding how implementation strategies produce desired effects.
Three-dimensional (3D) structures of protein complexes provide fundamental information to decipher biological processes at the molecular scale. The vast amount of experimentally and computationally ...resolved protein-protein interfaces (PPIs) offers the possibility of training deep learning models to aid the predictions of their biological relevance. We present here DeepRank, a general, configurable deep learning framework for data mining PPIs using 3D convolutional neural networks (CNNs). DeepRank maps features of PPIs onto 3D grids and trains a user-specified CNN on these 3D grids. DeepRank allows for efficient training of 3D CNNs with data sets containing millions of PPIs and supports both classification and regression. We demonstrate the performance of DeepRank on two distinct challenges: The classification of biological versus crystallographic PPIs, and the ranking of docking models. For both problems DeepRank is competitive with, or outperforms, state-of-the-art methods, demonstrating the versatility of the framework for research in structural biology.
ABSTRACT
We have searched for weak fast radio burst (FRB) events using a data base containing 568 736 756 transient events detected using the Parkes radio telescope between 1997 and 2001. In order to ...classify these pulses, and to identify likely FRB candidates, we used a machine-learning algorithm based on ResNet. We identified 81 new candidate FRBs and provide details of their positions, event times, and dispersion measures. These events were detected in only one beam of the Parkes multibeam receiver. We used a relatively low S/N cut-off threshold when selecting these bursts and some have dispersion measures only slightly exceeding the expected Galactic contribution.
We therefore present these candidate FRBs as a guide for follow-up observations in the search for repeating FRBs.
ABSTRACT Fast radio bursts (FRBs) are newly discovered radio transient sources. Their high dispersion measures indicate an extragalactic origin. However, due to the lack of observational data in ...other wavelengths, their progenitors still remain unclear. Here we suggest that the collisions between neutron stars (NSs) and asteroids/comets are promising mechanisms for FRBs. During the impact process, a hot plasma fireball forms after the material of the small body penetrates into the NS surface. The ionized matter inside the fireball then expands along the magnetic field lines. Coherent radiation from the thin shell at the top of the fireball will account for the observed FRBs. Our scenario can reasonably explain the main features of FRBs, such as their durations, luminosities, and the event rate. We argue that for a single NS, FRBs are not likely to happen repeatedly in a forseeable timespan since such impacts are of low probability. We predict that faint remnant X-ray emissions should be associated with FRBs, but it may be too faint to be detected by detectors at work.
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