A paradigmatic test of executive control, the
-back task, is known to recruit a widely distributed parietal, frontal, and striatal “executive network,” and is thought to require an equally wide array ...of executive functions. The mapping of functions onto substrates in such a complex task presents a significant challenge to any theoretical framework for executive control. To address this challenge, we developed a biologically constrained model of the
-back task that emergently develops the ability to appropriately gate, bind, and maintain information in working memory in the course of learning to perform the task. Furthermore, the model is sensitive to proactive interference in ways that match findings from neuroimaging and shows a U-shaped performance curve after manipulation of prefrontal dopaminergic mechanisms similar to that observed in studies of genetic polymorphisms and pharmacological manipulations. Our model represents a formal computational link between anatomical, functional neuroimaging, genetic, behavioral, and theoretical levels of analysis in the study of executive control. In addition, the model specifies one way in which the pFC, BG, parietal, and sensory cortices may learn to cooperate and give rise to executive control.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We use a biologically grounded neural network model to investigate the brain mechanisms underlying individual differences specific to the selection and instantiation of representations that exert ...cognitive control in task switching. Existing computational models of task switching do not focus on individual differences and so cannot explain why task switching abilities are separable from other executive function (EF) abilities (such as response inhibition). We explore hypotheses regarding neural mechanisms underlying the “Shifting-Specific” and “Common EF” components of EF proposed in the Unity/Diversity model (Miyake & Friedman, 2012) and similar components in related theoretical frameworks. We do so by adapting a well-developed neural network model of working memory (Prefrontal cortex, Basal ganglia Working Memory or PBWM; Hazy, Frank, & O’Reilly, 2007) to task switching and the Stroop task, and comparing its behavior on those tasks under a variety of individual difference manipulations. Results are consistent with the hypotheses that variation specific to task switching (i.e., Shifting-Specific) may be related to uncontrolled, automatic persistence of goal representations, whereas variation general to multiple EFs (i.e., Common EF) may be related to the strength of PFC representations and their effect on processing in the remainder of the cognitive system. Moreover, increasing signal to noise ratio in PFC, theoretically tied to levels of tonic dopamine and a genetic polymorphism in the COMT gene, reduced Stroop interference but increased switch costs. This stability–flexibility tradeoff provides an explanation for why these two EF components sometimes show opposing correlations with other variables such as attention problems and self-restraint.
•We present a neural network model of individual differences in task switching.•We compared results for a Stroop model that captures general executive ability.•Active goal maintenance and top-down biasing affected both switch and Stroop cost.•Persistence of no-longer-relevant goals increased switch cost but not Stroop cost.•These mechanisms may create some of the unity and diversity of executive functions.
Optimal management following index laparotomy is poorly defined in secondary peritonitis patients. Although "open abdomen" (OA), or temporary abdominal closure with planned relaparotomy, is used to ...reassess bowel viability or severity of contamination, recent studies demonstrate comparable morbidity and mortality with primary abdominal closure (PC). This study evaluates differences between OA and PC following emergent laparotomy.
Using the Premier database at a quaternary care center (2012-2016), nontrauma patients with secondary peritonitis requiring emergent laparotomy were identified (N = 534). Propensity matching for PC (n = 331; 62%) or OA (n = 203; 38%) was performed using variables: Mannheim Peritonitis Index, lactate, and vasopressor requirement. One hundred eleven closely matched pairs (PC:OA) were compared.
Five hundred thirty-four patients (55.0% female; mean age, 59.6 ± 15.5 years) underwent emergent laparotomy. Of the OA patients, 136 (67.0%) had one relaparotomy, while 67 (33.0%) underwent multiple reoperations. Compared to daytime cases, laparotomies performed overnight (6 pm-6 am) had more temporary closures with OA (42.8% OA vs. 57.2% PC, p = 0.04). When assessing by surgeon type, PC was performed in 78.7% of laparotomies by surgical subspecialties compared to 56.7% (p < 0.0001) of acute care surgeons. After propensity matching, OA patients had increased postoperative complications (71.2% vs. 41.4%, p < 0.0001), mortality (22.5% vs. 11.7%, p = 0.006), and longer median length of stay (13 vs. 9 days, p = 0.0001).
Open abdomen was performed in 38.0% of patients, with one-third of those requiring multiple reoperations. Complications, mortality rates, and costs associated with OA were significantly increased when compared to PC. Given these findings, future studies are needed to determine appropriate indications for OA.
Therapeutic/care management, level IV.
Emergent Laparoscopic Ventral Hernia Repairs Kao, Angela M.; Huntington, Ciara R.; Otero, Javier ...
The Journal of surgical research,
December 2018, 2018-12-00, 20181201, Letnik:
232
Journal Article
Recenzirano
Emergent repairs of incarcerated and strangulated ventral hernia repairs (VHR) are associated with higher perioperative morbidity and mortality than those repaired electively. Despite increasing ...utilization of minimally invasive techniques in elective repairs, the role for laparoscopy in emergent VHR is not well defined, and its feasibility has been demonstrated only in single center studies.
The American College of Surgeons National Surgical Quality Improvement Program database (2009-2016) was queried for emergent VHR. Laparoscopic and open techniques were compared using univariate and multivariate analyses.
A total of 11,075 patients who underwent emergent ventral and incisional hernia repairs were identified: 85.5% open ventral hernia repair (OVHR), 14.5% laparoscopic ventral hernia repair (LVHR). Patients who underwent emergent OVHRs were older, more comorbid, and more likely to be septic at the time of surgery than those undergoing emergent LVHRs. Emergent OVHR patients were more likely to have minor complications (22.1% versus 11.0%; OR 1.7; 95% CI 1.069-2.834). After controlling for confounding variables, LVHR and OVHR had similar outcomes, with the exception of higher rates of superficial surgical site infection in OVHR (5.0% versus 1.8%; odd's ratio (OR) 2.7; 95% confidence interval (CI) 1.176-6.138). Following multivariate analysis, laparoscopic approach demonstrated similar outcomes in major complications, reoperation, and 30-d mortality compared to open repairs. However, when controlling for other confounding factors, LVHR had reduced length of stay compared to OVHR (6.7 versus 4.0 d; 1.6 d longer, standard error 0.77, P < 0.03).
Emergent LVHR is associated with fewer superficial surgical site infection and shorter length of stay than OVHR but no difference in major complications, reoperation or 30-d mortality is associated with LVHR in the emergency setting.
Purpose
To compare the effect of home intravenous (IV) versus oral antibiotic therapy on complication rates and resource utilization following appendectomy for perforated appendicitis.
Methods
This ...was a randomized controlled trial of patients aged 4–17 with surgically treated perforated appendicitis from January 2011 to November 2013. Perforation was defined intraoperatively and divided into three grades: I—contained perforation, II—localized contamination to right gutter/pelvis, and III—diffuse contamination. Patients were randomized to complete a ten-day course of home antibiotic therapy with either IV ertapenem or oral amoxicillin–clavulanate. Thirty-day postoperative complication rates including abscess, readmission, wound infection, and charges were compared.
Results
Eighty-two patients were enrolled. Forty four (54%) were randomized to the IV group and 38 (46%) to the oral group. IV patients were older (12.3 ± 3.6 versus 10.1 ± 3.6,
p
< 0.05) with higher BMI (20.9 ± 5.8 versus 17.9 ± 3.5,
p
< 0.05). There were no differences in gender, comorbidities, or perforation grade (I—20.4% vs. 26.3%, II—36.4% vs. 34.2%, III—43.2% vs. 39.5%, all
p
> 0.05). Comparing IV to oral, there was no difference in length of stay (4.4 ± 1.5 versus 4.4 ± 2.0 days,
p
> 0.05), postoperative abscess rate (11.6% vs. 8.1%,
p
> 0.05), or readmission rate (14.0% vs. 16.2%,
p
> 0.05). Hospital and outpatient charges were higher in the IV group (
p
< 0.0001).
Conclusion
Oral antibiotics had equivalent outcomes and incurred fewer charges than IV antibiotics following appendectomy for perforated appendicitis.
IQ predicts many measures of life success, as well as trajectories of brain development. Prolonged cortical thickening observed in individuals with high IQ might reflect an extended period of ...synaptogenesis and high environmental sensitivity or plasticity. We tested this hypothesis by examining the timing of changes in the magnitude of genetic and environmental influences on IQ as a function of IQ score. We found that individuals with high IQ show high environmental influence on IQ into adolescence (resembling younger children), whereas individuals with low IQ show high heritability of IQ in adolescence (resembling adults), a pattern consistent with an extended sensitive period for intellectual development in more-intelligent individuals. The pattern held across a corss-sectional sample of almost 11,000 twin pairs and a longitudinal sample of twins, biological siblings, and adoptive siblings.
In the face of an increasingly aged population, surgical management in the elderly will rise. This study assesses the short-term outcomes of esophagectomies in octogenarians.
The National Surgical ...Quality Improvement Program database was queried for esophagectomy cases from 2005 to 2014. Patients aged <80 and ≥80 y were compared in univariate and multivariate analysis, controlling for confounding variables.
Among 9354 esophagectomies, 4.3% were performed in patients aged ≥80 y. Ivor Lewis was the most common approach, comprising 43% of cases. Octogenarians more frequently had dependent functional status (P < 0.0001) and cardiovascular disease (P < 0.0001), whereas younger patients were more likely obese (P < 0.0001), smokers (P < 0.0001), and have excess preoperative weight loss (P = 0.0043). Compared to younger patients, in multivariate analysis, elderly patients were noted to have increased risk of 30-d mortality (odds ratio OR 1.67; confidence interval CI 1.03-2.67), discharge to facility (OR 3.08; CI 2.36-4.02), myocardial infarction (OR 2.49; CI 1.29-4.82), and pneumonia (OR 1.47; CI 1.12-1.910). However, regardless of age, dependent functional status demonstrated the strongest association with mortality (OR 3.41; CI 2.14-6.61). Within the elderly, each additional year above 80 y old increased the risk of discharge to a facility by 17% (OR 1.17; CI 1.04-1.30). Cases requiring nongastric intestinal conduit were also more likely to suffer from early mortality (OR 2.87; CI 1.87-4.40).
Age is independently associated with multiple adverse outcomes, including mortality, discharge to facility, and postoperative cardiopulmonary complications. Functional dependence is even more so associated with poor outcomes. Careful selection of very elderly patients is required to minimize additional risk.
Although much genetic research has addressed normal variation in intelligence, little is known about the etiology of high cognitive abilities. Using data from 11,000 twin pairs (age ...range = 6–71 years) from the genetics of high cognitive abilities consortium, we investigated the genetic and environmental etiologies of high general cognitive ability (
g
). Age-appropriate psychometric cognitive tests were administered to the twins and used to create
g
scores standardized within each study. Liability-threshold model fitting was used to estimate genetic and environmental parameters for the top 15% of the distribution of
g
. Genetic influence for high
g
was substantial (0.50, with a 95% confidence interval of 0.41–0.60). Shared environmental influences were moderate (0.28, 0.19–0.37). We conclude that genetic variation contributes substantially to high
g
in Australia, the Netherlands, the United Kingdom and the United States.
Dengue, a leading cause of illness and death in the tropics and subtropics since the 1950׳s, is fast spreading in the Western hemisphere. Over 30% of the world׳s population is at risk for the ...mosquitoes that transmit any one of four related Dengue viruses (DENV). Infection induces lifetime protection to a particular serotype, but successive exposure to a different DENV increases the likelihood of severe form of dengue fever (DF), dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS). Prompt supportive treatment lowers the risk of developing the severe spectrum of Dengue-associated physiopathology. Vaccines are not available, and the most effective protective measure is to prevent mosquito bites. Here, we discuss selected aspects of the syndemic nature of Dengue, including its potential for pathologies of the central nervous system (CNS). We examine the fundamental mechanisms of cell-mediated and humoral immunity to viral infection in general, and the specific implications of these processes in the regulatory control of DENV infection, including DENV evasion from immune surveillance. In line with the emerging model of translational science in health care, which integrates translational research (viz., going from the patient to the bench and back to the patient) and translational effectiveness (viz., integrating and utilizing the best available evidence in clinical settings), we examine novel and timely evidence-based revisions of clinical practice guidelines critical in optimizing the management of DENV infection and Dengue pathologies. We examine the role of tele-medicine and stakeholder engagement in the contemporary model of patient centered, effectiveness-focused and evidence-based health care.
BBB - blood-brain barrier, CNS - central nervous system, DAMP - damage-associated molecular patterns, DENV - dengue virus, DF - dengue fever, DHF - dengue hemorrhagic fever, DSS - dengue shock syndrome, DALYs - isability adjusted life years, IFN-g - interferon-gamma, ILX - interleukinX, JAK/STAT - janus kinase (JAK) / Signal transducer and activator of transcription (STAT), LT - Escherichia coli heat-labile enterotoxin formulations deficient in GM1 binding by mutation (LTG33D), MCP-1 - monocyte chemotactic protein 1, M-CSF - macrophage colony-stimulating fact, MHC - major histocompatibility complex, MIF - macrophage migration inhibitory factor, MIP-1-α / -β - macrophage inflammatory protein-1 alpha and beta, mAb - monoclonal antibody, NS1 - non-structural protein 1 of dengue virus, NK - natural killer cells, PAMP - pathogen-associated molecular patterns, PBMC - peripheral blood mononuclear cells, TBF-b - transforming growth factor-beta, TNF-α - tumor necrosis-alpha, VHFs - virus hemorrhagic fevers, WHO - World Health Organization.
The Developmental Etiology of High IQ Brant, Angela M.; Haberstick, Brett C.; Corley, Robin P. ...
Behavior genetics,
07/2009, Letnik:
39, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The genetic and environmental trends in IQ development were assessed in 483 same-sex twin pairs in the Colorado longitudinal twin study using maximum-likelihood model-fitting analysis. The twins were ...assessed periodically from ages 1 to 16. Results show a decreasing influence of shared environment and an increasing influence of heritability across development, with large and increasing age to age stability of genetic influences. Non-shared environment contributes almost exclusively to age to age change. Similar analyses were conducted designating the top 15% of the sample as having high IQ at each age. The developmental etiology of high IQ did not significantly differ from that found for the continuous measure in this relatively novel analysis. These results demonstrate early stability in etiological influences on IQ and have potential implications for gene-finding efforts, suggesting that samples selected for high IQ can be used to find genetic variation that will be applicable to the full range of the IQ distribution, although conclusive demonstration that the same genes are indeed involved was beyond the scope of this study.
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