Resting-state connectivity and functional specialization in human medial parieto-occipital cortex

According to recent models of visuo-spatial processing, the medial parieto-occipital cortex is a crucial node of the dorsal visual stream. Evidence from neurophysiological studies in monkeys has indicated that the parieto-occipital sulcus (POS) contains three functionally and cytoarchitectonically distinct areas: the visual area V6 in the fundus of the POS, and the visuo-motor areas V6Av and V6Ad in a progressively dorsal and anterior location with respect to V6. Besides different topographical organization, cytoarchitectonics, and functional properties, these three monkey areas can also be distinguished based on their patterns of cortico-cortical connections. Thanks to wide-field retinotopic mapping, areas V6 and V6Av have been also mapped in the human brain. Here, using a combined approach of resting-state functional connectivity and task-evoked activity by fMRI, we identified a new region in the anterior POS showing a pattern of functional properties and cortical connections that suggests a homology with the monkey area V6Ad. In addition, we observed distinct patterns of cortical connections associated with the human V6 and V6Av which are remarkably consistent with those showed by the anatomical tracing studies in the corresponding monkey areas. Consistent with recent models on visuo-spatial processing, our findings demonstrate a gradient of functional specialization and cortical connections within the human POS, with more posterior regions primarily dedicated to the analysis of visual attributes useful for spatial navigation and more anterior regions primarily dedicated to analyses of spatial information relevant for goal-directed action

Quasi-local masses and cosmological coupling of black holes and mimickers

Motivated by the recent heated debate on whether the masses of local objects, such as compact stars or black holes (BHs), may be affected by the large-scale, cosmological dynamics, we analyze the conditions under which, in a general relativity framework, such a coupling small/large scales is allowed. We shed light on some controversial arguments, which have been used to rule out the latter possibility. We find that the cosmological coupling occurs whenever the energy of the central objects is quantified by the quasi-local Misner-Sharp mass (MS). Conversely, the decoupling occurs whenever the MS mass is fully equivalent to the (nonlocal) Arnowitt-Deser-Misner (ADM) mass. Consequently, for singular BHs embedded in cosmological backgrounds, like the Schwarzschild-de Sitter or McVittie solutions, we show that there is no cosmological coupling, confirming previous results in the literature. Furthermore, we show that nonsingular compact objects couple to the cosmological background, as quantified by their MS mass. We conclude that observational evidence of cosmological coupling of astrophysical BHs would be the smoking gun of their nonsingular nature.Comment: 16 pages, no figures, some discussions expanded, matches version published on JCA

Scalar stars and lumps with (A)dS core

We explore the possibility of embedding regular compact objects with (anti) de Sitter ((A)dS) core as solutions of Einstein's gravity minimally coupled to a real scalar field. We consider, among others, solutions interpolating between an inner, potential-dominated core and an outer, kinetic-term-dominated region. Owing to their analogy with slow-roll inflation, we term them gravitational vacuum inflative stars, or gravistars for short. We systematically discuss approximate solutions of the theory describing either the core or the asymptotically-flat region at spatial infinity. We extend nonexistence theorems for smooth interpolating solutions, previously proved for black holes, to compact objects without event horizons. This allows us to construct different classes of exact (either smooth or non-smooth) singularity-free solutions of the theory. We first find a smooth solution interpolating between an AdS spacetime in the core and an asymptotically-flat spacetime (a Schwarzschild solution with a subleading $1/r^2$ deformation). We proceed by constructing non-smooth solutions describing gravistars. Finally, we derive a smooth scalar lump solution interpolating between $\text{AdS}_4$ in the core and a Nariai spacetime at spatial infinity.Comment: 26 pages, 5 figures, 1 appendi

A common neural substrate for processing scenes and egomotion-compatible visual motion

Neuroimaging studies have revealed two separate classes of category-selective regions specialized in optic flow (egomotion-compatible) processing and in scene/place perception. Despite the importance of both optic flow and scene/place recognition to estimate changes in position and orientation within the environment during self-motion, the possible functional link between egomotion- and scene-selective regions has not yet been established. Here we reanalyzed functional magnetic resonance images from a large sample of participants performing two well-known “localizer” fMRI experiments, consisting in passive viewing of navigationally relevant stimuli such as buildings and places (scene/place stimulus) and coherently moving fields of dots simulating the visual stimulation during self-motion (flow fields). After interrogating the egomotion-selective areas with respect to the scene/place stimulus and the scene-selective areas with respect to flow fields, we found that the egomotion-selective areas V6+ and pIPS/V3A responded bilaterally more to scenes/places compared to faces, and all the scene-selective areas (parahippocampal place area or PPA, retrosplenial complex or RSC, and occipital place area or OPA) responded more to egomotion-compatible optic flow compared to random motion. The conjunction analysis between scene/place and flow field stimuli revealed that the most important focus of common activation was found in the dorsolateral parieto-occipital cortex, spanning the scene-selective OPA and the egomotion-selective pIPS/V3A. Individual inspection of the relative locations of these two regions revealed a partial overlap and a similar response profile to an independent low-level visual motion stimulus, suggesting that OPA and pIPS/V3A may be part of a unique motion-selective complex specialized in encoding both egomotion- and scene-relevant information, likely for the control of navigation in a structured environment

Single cell cloning and recombinant monoclonal antibodies generation from RA synovial B cells reveal frequent targeting of citrullinated histones of NETs

This work was funded by research grants from Arthritis Research UK (grant 20089 to MB; grant 20858 to ECo; Arthritis Research UK Experimental Arthritis Treatment Centre - grant 20022 to CP) and the William Harvey Research Foundation (WHRF grant 2011–2013 to MB); Elisa Corsiero was recipient of short-term travel fellowships from EMBO (ASTF 318-2010 and ASTF 102-2013

The Human Homologue of Macaque Area V6A

In macaque monkeys, V6A is a visuomotor area located in the anterior bank of the POs, dorsal and anterior to retinotopically-organized extrastriate area V6 (Galletti et al 1996). Unlike V6, V6A represents both contra- and ipsilateral visual fields and is broadly retinotopically organized (Galletti et al 1999b). The contralateral lower visual field is over-represented in V6A. The central 20°-30° of the visual field are mainly represented dorsally (V6Ad) and the periphery ventrally (V6Av), at the border with V6. Both sectors of area V6A contain arm movement-related cells, active during spatially-directed reaching movements (Gamberini et al., 2011). In humans, we previously mapped the retinotopic organization of area V6 (Pitzalis et al., 2006). Here, using phase-encoded fMRI, cortical surface-based analysis and wide-field retinotopic mapping, we define a new cortical region that borders V6 anteriorly and shows a clear over-representation of the contralateral lower visual field and of the periphery. As with macaque V6A, the eccentricity increases moving ventrally within the area. The new region contains a non-mirror-image representation of the visual field. Functional mapping reveals that, as in macaque V6A, the new region, but not the nearby area V6, responds during finger pointing and reaching movements. Based on similarity in position, retinotopic properties, functional organization and relationship with the neighbouring extrastriate visual areas, we propose that the new cortical region is the human homologue of macaque area V6A

Cosmological coupling of nonsingular black holes

We show that -- in the framework of general relativity (GR) -- if black holes (BHs) are singularity-free objects, they couple to the large-scale cosmological dynamics. We find that the leading contribution to the resulting growth of the BH mass ($M_{\rm BH}$) as a function of the scale factor $a$ stems from the curvature term, yielding $M_{\rm BH} \propto a^k$, with $k=1$. We demonstrate that such a linear scaling is universal for spherically-symmetric objects, and it is the only contribution in the case of regular BHs. For nonsingular horizonless compact objects we instead obtain an additional subleading model-dependent term. We conclude that GR nonsingular BHs/horizonless compact objects, although cosmologically coupled, are unlikely to be the source of dark energy. We test our prediction with astrophysical data by analysing the redshift dependence of the mass growth of supermassive BHs in a sample of elliptical galaxies at redshift $z=0.8 -0.9$. We also compare our theoretical prediction with higher redshift BH mass measurements obtained with the James Webb Space Telescope (JWST). We find that, while $k=1$ is compatible within $1 \sigma$ with JWST results, the data from elliptical galaxies at $z=0.8 -0.9$ favour values of $k>1$. New samples of BHs covering larger mass and redshift ranges and more precise BH mass measurements are required to settle the issue.Comment: 12 pages, 2 figures, discussions/references added, matches the version published in JCA

Cosmological coupling of nonsingular black holes

We show that — in the framework of general relativity (GR) — if black holes (BHs) are singularity-free objects, they couple to the large-scale cosmological dynamics. We find that the leading contribution to the resulting growth of the BH mass (M BH) as a function of the scale factor a stems from the curvature term, yielding M BH ∝ ak , with k = 1. We demonstrate that such a linear scaling is universal for spherically-symmetric objects, and it is the only contribution in the case of regular BHs. For nonsingular horizonless compact objects we instead obtain an additional subleading model-dependent term. We conclude that GR nonsingular BHs/horizonless compact objects, although cosmologically coupled, are unlikely to be the source of dark energy. We test our prediction with astrophysical data by analysing the redshift dependence of the mass growth of supermassive BHs in a sample of elliptical galaxies at redshift z = 0.8-0.9. We also compare our theoretical prediction with higher redshift BH mass measurements obtained with the James Webb Space Telescope (JWST). We find that, while k = 1 is compatible within 1σ with JWST results, the data from elliptical galaxies at z = 0.8-0.9 favour values of k > 1. New samples of BHs covering larger mass and redshift ranges and more precise BH mass measurements are required to settle the issue

Hepatocyte Growth Factor Receptor c-Met Instructs T Cell Cardiotropism and Promotes T Cell Migration to the Heart via Autocrine Chemokine Release

© 2015 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)This study was funded by the British Heart Foundation (RG/09/002/2642 to F.M.M.-B.) and the Medical Research Council of the UK (G0901084 to F.M.M.-B.). ImageStream X was funded by the Wellcome Trust (101604/Z/13/Z). This work forms part of the research themes contributing to the translational research portfolio of Barts and the London Cardiovascular Biomedical Research Unit, which is supported and funded by the National Institute of Health Research