Evaluation of atlas-based segmentation of hippocampi in healthy humans

Introduction and aim: Region of interest (ROI)-based functional magnetic resonance imaging (fMRI) data analysis relies on extracting signals from a specific area which is presumed to be involved in the brain activity being studied. The hippocampus is of interest in many functional connectivity studies for example in epilepsy as it plays an important role in epileptogenesis. In this context, ROI may be defined using different techniques. Our study aims at evaluating the spatial correspondence of hippocampal ROIs obtained using three brain atlases with hippocampal ROI obtained using an automatic segmentation algorithm dedicated to the hippocampus. Material and methods: High-resolution volumetric T1-weighted MR images of 18 healthy volunteers (five females) were acquired on a 3T scanner. Individual ROIs for both hippocampi of each subject were segmented from the MR images using an automatic hippocampus and amygdala segmentation software called SACHA providing the gold standard ROI for comparison with the atlas-derived results. For each subject, hippocampal ROIs were also obtained using three brain atlases: PickAtlas available as a commonly used software toolbox; automated anatomical labeling (AAL) atlas included as a subset of ROI into PickAtlas toolbox and a frequency-based brain atlas by Hammers et al. The levels of agreement between the SACHA results and those obtained using the atlases were assessed based on quantitative indices measuring volume differences and spatial overlap. The comparison was performed in standard Montreal Neurological Institute space, the registration being obtained with SPM5 (http://www.fil.ion.ucl.ac.uk/spm/). Results: The mean volumetric error across all subjects was 73% for hippocampal ROIs derived from AAL atlas; 20% in case of ROIs derived from the Hammers atlas and 107% for ROIs derived from PickAtlas. The mean false-positive and false-negative classification rates were 60% and 10% respectively for the AAL atlas; 16% and 32% for the Hammers atlas and 6% and 72% for the PickAtlas. Conclusion: Though atlas-based ROI definition may be convenient, the resulting ROIs may be poor representations of the hippocampus in some studies critical to under- or oversampling. Performance of the AAL atlas was inferior to that of the Hammers atlas. Hippocampal ROIs derived from PickAtlas are highly significantly smaller, and this results in the worst performance out of three atlases. It is advisable that the defined ROIs should be verified with knowledge of neuroanatomy before using it for further data analysis

Compared to What? Judicial Review and Other Veto Points in Contemporary Political Theory

Many democratic and jurisprudential theorists have too often uncritically accepted Alexander Bickel’s notion of “the countermajoritarian difficulty” when considering the relationship between judicial review and democracy; this is the case for arguments both for and against judicial review. This framework is both theoretically and empirically unsustainable. Democracy is not wholly synonymous with majoritarianism, and judicial review is not inherently countermajoritarian in the first place. In modern democratic political systems, judicial review is one of many potential veto points. Since all modern democratic political systems contain veto points, the relevant and unexplored question is what qualities might make a veto point relatively democratic. Proceeding on the assumption that democracy’s primary normative value is found in its opposition to domination by both state and private actors, we make a preliminary effort to delineate what qualities a democratic veto point might have, identifying five criteria, and evaluate judicial review using these criteria. We conclude that judicial review’s performance against these criteria is decidedly mixed, but in the final balance, it is likely to be a modest net positive for democracy, particularly when compared to other veto points commonly found in contemporary democratic political systems

Independent component analysis of interictal fMRI in focal epilepsy: comparison with general linear model-based EEG-correlated fMRI

The general linear model (GLM) has been used to analyze simultaneous EEG–fMRI to reveal BOLD changes linked to interictal epileptic discharges (IED) identified on scalp EEG. This approach is ineffective when IED are not evident in the EEG. Data-driven fMRI analysis techniques that do not require an EEG derived model may offer a solution in these circumstances. We compared the findings of independent components analysis (ICA) and EEG-based GLM analyses of fMRI data from eight patients with focal epilepsy. Spatial ICA was used to extract independent components (IC) which were automatically classified as either BOLD-related, motion artefacts, EPI-susceptibility artefacts, large blood vessels, noise at high spatial or temporal frequency. The classifier reduced the number of candidate IC by 78%, with an average of 16 BOLD-related IC. Concordance between the ICA and GLM-derived results was assessed based on spatio-temporal criteria. In each patient, one of the IC satisfied the criteria to correspond to IED-based GLM result. The remaining IC were consistent with BOLD patterns of spontaneous brain activity and may include epileptic activity that was not evident on the scalp EEG. In conclusion, ICA of fMRI is capable of revealing areas of epileptic activity in patients with focal epilepsy and may be useful for the analysis of EEG–fMRI data in which abnormalities are not apparent on scalp EEG

How Perpetrator Identity (Sometimes) Influences Media Framing Attacks as “Terrorism” or “Mental Illness”

Do media frame attacks with Muslim perpetrators as “terrorism” and attacks with White perpetrators as the result of “mental illness”? Despite public speculation and limited academic work with relatively small subsets of cases, there have been no systematic analyses of potential biases in how media frame terrorism. We addressed this gap by examining the text of print news coverage of all terrorist attacks in the United States between 2006 and 2015. Controlling for fatalities, affiliation with a group, and existing mental illness, the odds that an article references terrorism are approximately five times greater for a Muslim versus a non-Muslim perpetrator. In contrast, the odds that an article references mental illness do not significantly differ between White and non-White perpetrators. Results partially confirm public speculation and are robust against numerous alternative explanations. Differences in media framing can influence public (mis)perceptions of violence and threats, and ultimately harm counterterrorism policy

When Data Do Not Matter: Exploring Public Perceptions of Terrorism

Public perceptions of terrorism are out of line with reality. How can perceptions be changed? Using a 4 × 2 experimental design with a national sample of U.S. adults, we examine how source of information and details provided impact views of terrorism. Sources, details, and individual-level factors—Islamophobia, trust in media, and trust in science—impact perceived accuracy of terrorism data. Many people updated their views on terrorism after reading factual information, yet only trust in science was related with this change. In short, people can be persuaded by factual information on terrorism, but it is less clear why they change beliefs

A Redescription of the First Instar of Rhantus calidus (Fabricius) (Coleoptera: Dytiscidae) with Notes on its Biology

First instars of Rhantus calidus (Fabricius) representing a Georgia population are described and illustrated. Dimensions are provided along with an analysis of the primary chaetotaxy of legs, head, and last abdominal segment. The presence of first instars at the study site demonstrated that R. calidus either requires or is at least tolerant of warmer temperatures for completion of its life cycle. Habitats with temperatures comparable to this site were likely present in a warm Atlantic coastal enclave during the last glacial maximum (LGM), making it probable that the LGM dytiscid fauna of Georgia included R. calidus

Corrections for Identification of Mature Larvae of Rhantus calidus (Fabricius) and Hoperius planatus Fall (Coleoptera: Dytiscidae) in Georgia

Characters for identification of mature larvae of Rhantus calidus and Hoperius planatus in Georgia are evaluated and critiqued. Ma­ture larvae of R. calidus have only eight cereal sensilla (setae) while those of Hoperius have numerous medial and lateral sensilla. This is presented as an obvious and reliable character set for identification of R. calidus and H. planatus in Georgia

Why Do Some Terrorist Attacks Receive More Media Attention Than Others?

Terrorist attacks often dominate news coverage as reporters seek to provide the public with information. Yet, not all incidents receive equal attention. Why do some terrorist attacks receive more media coverage than others? We argue that perpetrator religion is the largest predictor of news coverage, while target type, being arrested, and fatalities will also impact coverage. We examined news coverage from LexisNexis Academic and CNN.com for all terrorist attacks in the United States between 2006 and 2015 (N=136). Controlling for target type, fatalities, and being arrested, attacks by Muslim perpetrators received, on average, 357% more coverage than other attacks. Our results are robust against a number of counterarguments. The disparities in news coverage of attacks based on the perpetrator’s religion may explain why members of the public tend to fear the “Muslim terrorist” while ignoring other threats. More representative coverage could help to bring public perception in line with reality

Divergences in the Control of Mitochondrial Respiration Are Associated With Life-Span Variation in Marine Bivalves

The role played by mitochondrial function in the aging process has been a subject of intense debate in the past few decades, as part of the efforts to understand the mechanistic basis of longevity. The mitochondrial oxidative stress theory of aging suggests that a progressive decay of this organelle’s function leads to an exacerbation of oxidative stress, with a deleterious impact on mitochondrial structure and DNA, ultimately promoting aging. Among the traits suspected to be associated with longevity is the variation in the regulation of oxidative phosphorylation, potentially affecting the management of oxidative stress. Longitudinal studies using the framework of metabolic control analysis have shown age-related differences in the flux control of respiration, but this approach has seldom been taken on a comparative scale. Using 4 species of marine bivalves exhibiting a large range of maximum life span (from 28 years to 507 years), we report life-span-related differences in flux control at different steps of the electron transfer system. Increased longevity was characterized by a lower control by NADH (complex I-linked) and Succinate (complex II-linked) pathways, while respiration was strongly controlled by complex IV when compared to shorter-lived species. Complex III exerted strong control over respiration in all species. Furthermore, high longevity was associated with higher citrate synthase activity and lower ATP synthase activity. Relieving the control exerted by the electron entry pathways could be advantageous for reaching higher longevity, leading to increased control by complex IV, the final electron acceptor in the electron transfer system

Conceptual models for describing virtual worlds

A conceptual model of a virtual world is a high-level representation of how the objects behave and how they are related to each other. The conceptual models identify the most essential elements of the reality to be simulated. This is the first and a very important step in the process of designing a virtual world. Afterwards, specific and complex models can be implemented and inserted into these conceptual models. This paper provides an overview of existing conceptual models used to design virtual worlds. A number of existing frameworks and architecture for describing virtual worlds are classified into six kinds of conceptual models: unstructured, graphic-oriented, network-oriented, object-oriented, environment-oriented and relational graph-oriented representations. The advantages and issues regarding virtual world design, management, reusability and interoperability are discussed