135 research outputs found
Surprise and error: Common neuronal architecture for the processing of errors and novelty
According to recent accounts, the processing of errors and generally infrequent, surprising (novel) events share a common neuroanat-omical substrate. Direct empirical evidence for this common processing network in humans is, however, scarce. To test this hypothesis, we administered a hybrid error-monitoring/novelty-oddball task in which the frequency of novel, surprising trials was dynamically matched to the frequency of errors. Using scalp electroencephalographic recordings and event-related functional magnetic resonance imaging (fMRI), we compared neural responses to errors with neural responses to novel events. In Experiment 1, independent component analysis of scalp ERP data revealed a common neural generator implicated in the generation of both the error-related negativity (ERN) and the novelty-related frontocentral N2. In Experiment 2, this pattern was confirmed by a conjunction analysis of event-related fMRI, which showed significantly elevated BOLD activity following both types of trials in the posterior medial frontal cortex, including the anterior midcingulate cortex (aMCC), the neuronal generator of the ERN. Together, these findings provide direct evidence of a common neural system underlying the processing of errors and novel events. This appears to be at odds with prominent theories of the ERN and aMCC. Inparticular, there inforcement learning theory of the ERN may need to be modified because it may not suffice as a fully integrative model of aMCC function. Whenever course and outcome of anaction violates expectancies (not necessarily related to reward), the aMCC seems to be engaged in evaluating the necessity of behavioral adaptation. © 2012 the authors
A simplified primary aldosteronism surgical outcome score is a useful prediction model when target organ damage is unknown – Retrospective cohort study
Background: Cure of hypertension after adrenalectomy for primary aldosteronism is no certainty and therefore preoperative patient counseling is essential. The Primary Aldosteronism Surgical Outcome (PASO) Score is a useful prediction model with an area under the curve (AUC) of 0.839. The PASO Score includes ‘Target Organ Damage’ (TOD) (i.e., left ventricular hypertrophy and/or microalbuminuria), which is often unavailable during preoperative counseling and might therefore limit its use in clinical practice. We hypothesized that the PASO score would still be useful if TOD is unknown at time of counseling. Therefore, we aimed to examine the predictive performance of the simplified PASO Score, without taking TOD into account. Materials and methods: In this retrospective cohort study, patients who underwent unilateral adrenalectomy between 2010 and 2016 in 16 medical centers from North America, Europe and Australia were included. TOD was unknown in our database and therefore assigned as absent. Patients were classified as complete, partial or absent clinical success using the PASO consensus criteria. Results: A total of 380 (73.9%) patients were eligible for analysis. Complete, partial and absent clinical success were observed in 29.5%, 55.8% and 14.7% of patients, respectively. The simplified PASO Score had an AUC of 0.730 (95% confidence interval 0.674–0.785) in our total cohort. Conclusion: Without taking TOD into account, the simplified PASO Score had a lower predictive value as compared to the original derivation cohort. Ideally, the complete PASO Score should be used, but when data on TOD are not readily available, the simplified PASO Score is a useful and reasonable alternative
Adrenalectomy for Primary Aldosteronism:Significant Variability in Work-Up Strategies and Low Guideline Adherence in Worldwide Daily Clinical Practice
Background Various diagnostic tests are available to establish the primary aldosteronism (PA) diagnosis and to determine the disease laterality. Combined with the controversies in the literature, unawareness of guidelines and technical demands and high costs of some of these diagnostics, this could lead to significant differences in work-up strategies worldwide. Therefore, we investigated the work-up before surgery for PA in daily clinical practice within a multicenter study. Methods Patients who underwent unilateral adrenalectomy for PA within 16 centers in Europe, Canada, Australia and the USA between 2010 and 2016 were included. We did not exclude patients based on the performed diagnostic tests during work-up to make our data representative for current clinical practice. Adherence to the Endocrine Society Guideline and variables associated with not performing adrenal venous sampling (AVS) were analyzed. Results In total, 435 patients were eligible. An aldosterone-to-renin ratio, confirmatory test, computed tomography (CT), magnetic resonance imaging and AVS were performed in 82.9%, 32.9%, 86.9%, 17.0% and 65.3% of patients, respectively. A complete work-up, as recommended by the guideline, was performed in 13.1% of patients. Bilateral disease or normal adrenal anatomy on CT (OR 16.19; CI 3.50-74.99), smaller tumor size on CT (OR 0.06; CI 0.04-0.08) and presence of hypokalemia (OR 2.00; CI 1.19-3.32) were independently associated with performing AVS. Conclusions This study is the first to examine the daily clinical practice work-up of PA within a worldwide cohort of surgical patients. The results demonstrate significant variability in work-up strategies and low adherence to The Endocrine Society guideline
Gut Microbiota Composition of Biliary Atresia Patients Before Kasai Portoenterostomy Associates With Long-term Outcome
BACKGROUND AND AIMS: Biliary atresia (BA) is a cholestatic, fibro-obliterative cholangiopathy of unknown etiology. BA is primarily treated by a surgical approach, i.e. the Kasai portoenterostomy (KPE), to obtain clearance of jaundice (COJ). The gut microbiota (GM) composition has been associated with the course of several cholestatic liver diseases. It is largely unknown, however, whether GM composition associates with the outcome of KPE. We compared the GM composition of BA patients and controls and assessed if GM composition before KPE was related to COJ after KPE. METHODS: We compared feces of term born BA patients before KPE and controls (patients undergoing inguinal hernia repair) by 16S rRNA sequencing. Composition and alpha diversity of the GM were compared between BA and controls before KPE and after KPE, between patients with COJ vs. without COJ (total serum bilirubin < or ≥ 20 μmol/L < 6mo post-KPE). RESULTS: Alpha diversity was comparable between BA (n = 12, age 1.6[1.3-1.8]mo) and controls (n = 6, age 2.0[1.4-2.1]mo; P = 0.22). Compared to controls, BA patients had lower abundances of Bifidobacteriaceae (β=-1.98, P < 0.001) and Lachnospiraceae (β=-1.84, P = 0.007), and higher abundances of Streptococcus (β=1.13, P = 0.003). The alpha diversity prior to KPE correlated negatively with COJ (R = -0.63, P = 0.03). Lower alpha diversity pre-KPE was associated with COJ [+] (βlogit = -0.64, P = 0.04). We observed greater abundances of genus Acinetobacter (β=1.27, P = 0.03) and family Clostridiaceae (β=1.45, P = 0.03) and lower abundances of the family Enterobacteriaceae, (genera Klebsiella (β=-1.21, P = 0.01), Salmonella (β=-1.57, P = 0.02)) in COJ [+] vs. COJ [-]. CONCLUSIONS: The gut microbiota of biliary atresia patients prior to Kasai portoenterostomy associates with outcome, clearance of jaundice, suggestive of predictive and mechanistic roles of the gut microbiota composition in bile homeostasis
Surprise disrupts cognition via a fronto-basal ganglia suppressive mechanism
Surprising events markedly affect behaviour and cognition, yet the underlying mechanism is unclear. Surprise recruits a brain mechanism that globally suppresses motor activity, ostensibly via the subthalamic nucleus (STN) of the basal ganglia. Here, we tested whether this suppressive mechanism extends beyond skeletomotor suppression and also affects cognition (here, verbal working memory, WM). We recorded scalp-EEG (electrophysiology) in healthy participants and STN local field potentials in Parkinson's patients during a task in which surprise disrupted WM. For scalp-EEG, surprising events engage the same independent neural signal component that indexes action stopping in a stop-signal task. Importantly, the degree of this recruitment mediates surprise-related WM decrements. Intracranially, STN activity is also increased post surprise, especially when WM is interrupted. These results suggest that surprise interrupts cognition via the same fronto-basal ganglia mechanism that interrupts action. This motivates a new neural theory of how cognition is interrupted, and how distraction arises after surprising events
Area selection for diamonds using magnetotellurics : examples from southern Africa
Author Posting. © Elsevier B.V., 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Lithos 112 (2009): 83-92, doi:10.1016/j.lithos.2009.06.011.Southern Africa, particularly the Kaapvaal Craton, is one of the world’s best natural
laboratories for studying the lithospheric mantle given the wealth of xenolith and seismic data
that exist for it. The Southern African Magnetotelluric Experiment (SAMTEX) was launched
to complement these databases and provide further constraints on physical parameters and
conditions by obtaining information about electrical conductivity variations laterally and with
depth. Initially it was planned to acquire magnetotelluric data on profiles spatially coincident
with the Kaapvaal Seismic Experiment, however with the addition of seven more partners to
the original four through the course of the experiment, SAMTEX was enlarged from two to
four phases of acquisition, and extended to cover much of Botswana and Namibia. The
complete SAMTEX dataset now comprises MT data from over 675 distinct locations in an
area of over one million square kilometres, making SAMTEX the largest regional-scale MT
experiment conducted to date.
Preliminary images of electrical resistivity and electrical resistivity anisotropy at 100
km and 200 km, constructed through approximate one-dimensional methods, map resistive
regions spatially correlated with the Kaapvaal, Zimbabwe and Angola Cratons, and more
conductive regions spatially associated with the neighbouring mobile belts and the Rehoboth
Terrain. Known diamondiferous kimberlites occur primarily on the boundaries between the
resistive or isotropic regions and conductive or anisotropic regions.
Comparisons between the resistivity image maps and seismic velocities from models
constructed through surface wave and body wave tomography show spatial correlations
between high velocity regions that are resistive, and low velocity regions that are conductive.
In particular, the electrical resistivity of the sub-continental lithospheric mantle of the
Kaapvaal Craton is determined by its bulk parameters, so is controlled by a bulk matrix
property, namely temperature, and to a lesser degree by iron content and composition, and is
not controlled by contributions from interconnected conducting minor phases, such as
graphite, sulphides, iron oxides, hydrous minerals, etc. This makes quantitative correlations
between velocity and resistivity valid, and a robust regression between the two gives an
approximate relationship of Vs [m/s] = 0.045*log(resistivity [ohm.m]).We especially thank our
academic funding sponsors; the Continental Dynamics programme of the U.S. National
Science Foundation, the South African Department of Science and Technology, and Science
Foundation Ireland
Submarine slope failures along the convergent continental margin of the Middle America Trench
We present the first comprehensive study of mass wasting processes in the continental slope of a convergent margin of a subduction zone where tectonic processes are dominated by subduction erosion. We have used multibeam bathymetry along ∼1300 km of the Middle America Trench of the Central America Subduction Zone and deep-towed side-scan sonar data. We found abundant evidence of large-scale slope failures that were mostly previously unmapped. The features are classified into a variety of slope failure types, creating an inventory of 147 slope failure structures. Their type distribution and abundance define a segmentation of the continental slope in six sectors. The segmentation in slope stability processes does not appear to be related to slope preconditioning due to changes in physical properties of sediment, presence/absence of gas hydrates, or apparent changes in the hydrogeological system. The segmentation appears to be better explained by changes in slope preconditioning due to variations in tectonic processes. The region is an optimal setting to study how tectonic processes related to variations in intensity of subduction erosion and changes in relief of the underthrusting plate affect mass wasting processes of the continental slope. The largest slope failures occur offshore Costa Rica. There, subducting ridges and seamounts produce failures with up to hundreds of meters high headwalls, with detachment planes that penetrate deep into the continental margin, in some cases reaching the plate boundary. Offshore northern Costa Rica a smooth oceanic seafloor underthrusts the least disturbed continental slope. Offshore Nicaragua, the ocean plate is ornamented with smaller seamounts and horst and graben topography of variable intensity. Here mass wasting structures are numerous and comparatively smaller, but when combined, they affect a large part of the margin segment. Farther north, offshore El Salvador and Guatemala the downgoing plate has no large seamounts but well-defined horst and graben topography. Off El Salvador slope failure is least developed and mainly occurs in the uppermost continental slope at canyon walls. Off Guatemala mass wasting is abundant and possibly related to normal faulting across the slope. Collapse in the wake of subducting ocean plate topography is a likely failure trigger of slumps. Rapid oversteepening above subducting relief may trigger translational slides in the middle Nicaraguan upper Costa Rican slope. Earthquake shaking may be a trigger, but we interpret that slope failure rate is lower than recurrence time of large earthquakes in the region. Generally, our analysis indicates that the importance of mass wasting processes in the evolution of margins dominated by subduction erosion and its role in sediment dynamics may have been previously underestimated
Induced pseudoscalar coupling of the proton weak interaction
The induced pseudoscalar coupling is the least well known of the weak
coupling constants of the proton's charged--current interaction. Its size is
dictated by chiral symmetry arguments, and its measurement represents an
important test of quantum chromodynamics at low energies. During the past
decade a large body of new data relevant to the coupling has been
accumulated. This data includes measurements of radiative and non radiative
muon capture on targets ranging from hydrogen and few--nucleon systems to
complex nuclei. Herein the authors review the theoretical underpinnings of
, the experimental studies of , and the procedures and uncertainties
in extracting the coupling from data. Current puzzles are highlighted and
future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic
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