Some argue that hippocampus supports declarative memory, our capacity to recall facts and events, whereas others view the hippocampus as part of a system dedicated to calculating routes through ...space, and these two contrasting views are pursued largely independently in current research. Here we offer a perspective on where these views can and cannot be reconciled and update a bridging framework that will improve our understanding of hippocampal function.
Currently, separate lines of research focus on hippocampal function in spatial navigation or in declarative memory. Here, Eichenbaum and Cohen update their relational memory account to reconcile these approaches and offer new insights into the fundamental mechanisms of memory.
Currency Power Cohen, Benjamin J
2015, 2015., 20150901, 2015-09-01
eBook
Overview: Monetary rivalry is a fact of life in the world economy. Intense competition between international currencies like the US dollar, Europe's euro, and the Chinese yuan is profoundly ...political, going to the heart of the global balance of power. But what exactly is the relationship between currency and power, and what does it portend for the geopolitical standing of the United States, Europe, and China? Popular opinion holds that the days of the dollar, long the world's dominant currency, are numbered. By contrast, Currency Power argues that the current monetary rivalry still greatly favors America's greenback. Benjamin Cohen shows why neither the euro nor the yuan will supplant the dollar at the top of the global currency hierarchy. Cohen presents an innovative analysis of currency power and emphasizes the importance of separating out the various roles that international money might have. After systematically exploring the links between currency internationalization and state power, Cohen turns to the state of play among today's top currencies. The greenback, he contends, is the "indispensable currency"--The one that the world can't do without. Only the dollar is backed by all the economic and political resources that make a currency powerful. Meanwhile, the euro is severely handicapped by structural defects in the design of its governance mechanisms, and the yuan suffers from various practical limitations in both finance and politics. Contrary to today's growing opinion, Currency Power demonstrates that the dollar will continue to be the leading global currency for some time to come.
Elucidating the role of the rodent hippocampus in object recognition memory is critical for establishing the appropriateness of rodents as models of human memory and for their use in the development ...of memory disorder treatments. In mammals, spatial memory 1–6 and nonspatial memory 7, 8 depend upon the hippocampus and associated medial temporal lobe (MTL) structures. Although well established in humans 1, 9, the role of the rodent hippocampus in object memory remains highly debated due to conflicting findings across temporary and permanent hippocampal lesion studies 10–22 and evidence that the perirhinal cortex may support object memory 17, 23, 24. In the current studies, we used intrahippocampal muscimol microinfusions to transiently inactivate the male C57BL/6J mouse hippocampus at distinct stages during the novel object recognition (NOR) task: during object memory encoding and consolidation, just consolidation, and/or retrieval. We also assessed the effect of temporary hippocampal inactivation when objects were presented in different contexts, thus eliminating the spatial or contextual components of the task. Lastly, we assessed extracellular dorsal hippocampal glutamate efflux and firing properties of hippocampal neurons while mice performed the NOR task. Our results reveal a clear and compelling role of the rodent hippocampus in nonspatial object memory.
•In mice, the hippocampus is required for distinct stages of object memory processing•Retrieval of object memory independent of context also requires the hippocampus•Glutamate efflux measurements during NOR support hippocampal involvement in mice•NOR test session performance increased firing rates of hippocampal pyramidal neurons
In vivo histology using magnetic resonance imaging (MRI) is a newly emerging research field that aims to non-invasively characterize tissue microstructure. The implications of in vivo histology are ...many, from discovering novel biomarkers to studying human development, to providing tools for disease diagnosis and monitoring the effects of novel treatments on tissue. This review focuses on quantitative MRI (qMRI) techniques that are used to map spinal cord microstructure. Opening with a rationale for non-invasive imaging of the spinal cord, this article continues with a brief overview of the existing MRI techniques for axon and myelin imaging, followed by the specific challenges and potential solutions for acquiring and processing such data. The final part of this review focuses on histological validation, with suggested tissue preparation, acquisition and processing protocols for large-scale microscopy.
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•Combine contrasts such as diffusion and magnetization transfer to gain specificity.•Standardize acquisition protocols to promote reproducibility and multi-center studies.•Standardize analysis methods via templates and open-source software to minimize bias.•Validation of qMRI using simulations, synthetic and ex vivo phantoms is necessary.
There are scant data on long-term clinical outcomes and bioprosthetic-valve function after transcatheter aortic-valve replacement (TAVR) as compared with surgical aortic-valve replacement in patients ...with severe aortic stenosis and intermediate surgical risk.
We enrolled 2032 intermediate-risk patients with severe, symptomatic aortic stenosis at 57 centers. Patients were stratified according to intended transfemoral or transthoracic access (76.3% and 23.7%, respectively) and were randomly assigned to undergo either TAVR or surgical replacement. Clinical, echocardiographic, and health-status outcomes were followed for 5 years. The primary end point was death from any cause or disabling stroke.
At 5 years, there was no significant difference in the incidence of death from any cause or disabling stroke between the TAVR group and the surgery group (47.9% and 43.4%, respectively; hazard ratio, 1.09; 95% confidence interval CI, 0.95 to 1.25; P = 0.21). Results were similar for the transfemoral-access cohort (44.5% and 42.0%, respectively; hazard ratio, 1.02; 95% CI, 0.87 to 1.20), but the incidence of death or disabling stroke was higher after TAVR than after surgery in the transthoracic-access cohort (59.3% vs. 48.3%; hazard ratio, 1.32; 95% CI, 1.02 to 1.71). At 5 years, more patients in the TAVR group than in the surgery group had at least mild paravalvular aortic regurgitation (33.3% vs. 6.3%). Repeat hospitalizations were more frequent after TAVR than after surgery (33.3% vs. 25.2%), as were aortic-valve reinterventions (3.2% vs. 0.8%). Improvement in health status at 5 years was similar for TAVR and surgery.
Among patients with aortic stenosis who were at intermediate surgical risk, there was no significant difference in the incidence of death or disabling stroke at 5 years after TAVR as compared with surgical aortic-valve replacement. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313.).
The post-thrombotic syndrome frequently develops in patients with proximal deep-vein thrombosis despite treatment with anticoagulant therapy. Pharmacomechanical catheter-directed thrombolysis ...(hereafter "pharmacomechanical thrombolysis") rapidly removes thrombus and is hypothesized to reduce the risk of the post-thrombotic syndrome.
We randomly assigned 692 patients with acute proximal deep-vein thrombosis to receive either anticoagulation alone (control group) or anticoagulation plus pharmacomechanical thrombolysis (catheter-mediated or device-mediated intrathrombus delivery of recombinant tissue plasminogen activator and thrombus aspiration or maceration, with or without stenting). The primary outcome was development of the post-thrombotic syndrome between 6 and 24 months of follow-up.
Between 6 and 24 months, there was no significant between-group difference in the percentage of patients with the post-thrombotic syndrome (47% in the pharmacomechanical-thrombolysis group and 48% in the control group; risk ratio, 0.96; 95% confidence interval CI, 0.82 to 1.11; P=0.56). Pharmacomechanical thrombolysis led to more major bleeding events within 10 days (1.7% vs. 0.3% of patients, P=0.049), but no significant difference in recurrent venous thromboembolism was seen over the 24-month follow-up period (12% in the pharmacomechanical-thrombolysis group and 8% in the control group, P=0.09). Moderate-to-severe post-thrombotic syndrome occurred in 18% of patients in the pharmacomechanical-thrombolysis group versus 24% of those in the control group (risk ratio, 0.73; 95% CI, 0.54 to 0.98; P=0.04). Severity scores for the post-thrombotic syndrome were lower in the pharmacomechanical-thrombolysis group than in the control group at 6, 12, 18, and 24 months of follow-up (P<0.01 for the comparison of the Villalta scores at each time point), but the improvement in quality of life from baseline to 24 months did not differ significantly between the treatment groups.
Among patients with acute proximal deep-vein thrombosis, the addition of pharmacomechanical catheter-directed thrombolysis to anticoagulation did not result in a lower risk of the post-thrombotic syndrome but did result in a higher risk of major bleeding. (Funded by the National Heart, Lung, and Blood Institute and others; ATTRACT ClinicalTrials.gov number, NCT00790335 .).
As the size of graphs for analysis continues to grow, methods of graph processing that scale well have become increasingly important. One way to handle large datasets is to disperse them across an ...array of networked computers, each of which implements simple sorting and accumulating, or MapReduce, operations. This cloud computing approach offers many attractive features. If decomposing useful graph operations in terms of MapReduce cycles is possible, it provides incentive for seriously considering cloud computing. Moreover, it offers a way to handle a large graph on a single machine that can't hold the entire graph as well as enables streaming graph processing. This article examines this possibility.
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