Mnemonic discrimination relates to perforant path integrity: An ultra-high resolution diffusion tensor imaging study.

Pattern separation describes the orthogonalization of similar inputs into unique, non-overlapping representations. This computational process is thought to serve memory by reducing interference and to be mediated by the dentate gyrus of the hippocampus. Using ultra-high in-plane resolution diffusion tensor imaging (hrDTI) in older adults, we previously demonstrated that integrity of the perforant path, which provides input to the dentate gyrus from entorhinal cortex, was associated with mnemonic discrimination, a behavioral outcome designed to load on pattern separation. The current hrDTI study assessed the specificity of this perforant path integrity-mnemonic discrimination relationship relative to other cognitive constructs (identified using a factor analysis) and white matter tracts (hippocampal cingulum, fornix, corpus callosum) in 112 healthy adults (20-87 years). Results revealed age-related declines in integrity of the perforant path and other medial temporal lobe (MTL) tracts (hippocampal cingulum, fornix). Controlling for global effects of brain aging, perforant path integrity related only to the factor that captured mnemonic discrimination performance. Comparable integrity-mnemonic discrimination relationships were also observed for the hippocampal cingulum and fornix. Thus, whereas perforant path integrity specifically relates to mnemonic discrimination, mnemonic discrimination may be mediated by a broader MTL network

Microstructural Alterations in Hippocampal Subfields Mediate Age-Related Memory Decline in Humans.

Aging, even in the absence of clear pathology of dementia, is associated with cognitive decline. Neuroimaging, especially diffusion-weighted imaging, has been highly valuable in understanding some of these changes in live humans, non-invasively. Traditional tensor techniques have revealed that the integrity of the fornix and other white matter tracts significantly deteriorates with age, and that this deterioration is highly correlated with worsening cognitive performance. However, traditional tensor techniques are still not specific enough to indict explicit microstructural features that may be responsible for age-related cognitive decline and cannot be used to effectively study gray matter properties. Here, we sought to determine whether recent advances in diffusion-weighted imaging, including Neurite Orientation Dispersion and Density Imaging (NODDI) and Constrained Spherical Deconvolution, would provide more sensitive measures of age-related changes in the microstructure of the medial temporal lobe. We evaluated these measures in a group of young (ages 20-38 years old) and older (ages 59-84 years old) adults and assessed their relationships with performance on tests of cognition. We found that the fiber density (FD) of the fornix and the neurite density index (NDI) of the fornix, hippocampal subfields (DG/CA3, CA1, and subiculum), and parahippocampal cortex, varied as a function of age in a cross-sectional cohort. Moreover, in the fornix, DG/CA3, and CA1, these changes correlated with memory performance on the Rey Auditory Verbal Learning Test (RAVLT), even after regressing out the effect of age, suggesting that they were capturing neurobiological properties directly related to performance in this task. These measures provide more details regarding age-related neurobiological properties. For example, a change in fiber density could mean a reduction in axonal packing density or myelination, and the increase in NDI observed might be explained by changes in dendritic complexity or even sprouting. These results provide a far more comprehensive view than previously determined on the possible system-wide processes that may be occurring because of healthy aging and demonstrate that advanced diffusion-weighted imaging is evolving into a powerful tool to study more than just white matter properties

Strong D* -> D+pi and B* -> B+pi couplings

We compute g_{D* D pi} and g_{B* B pi} using a framework in which all elements are constrained by Dyson-Schwinger equation studies of QCD, and therefore incorporates a consistent, direct and simultaneous description of light- and heavy-quarks and the states they may constitute. We link these couplings with the heavy-light-meson leptonic decay constants, and thereby obtain g_{D* D pi}=15.9+2.1/-1.0 and g_{B* B pi}=30.0+3.2/-1.4. From the latter we infer \hat-g_B=0.37+0.04/-0.02. A comparison between g_{D* D pi} and g_{B* B pi} indicates that when the c-quark is a system's heaviest constituent, Lambda_{QCD}/m_c-corrections are not under good control.Comment: 5 pages, 1 table, 2 figure

Limbic Tract Integrity Contributes to Pattern Separation Performance Across the Lifespan.

Accurate memory for discrete events is thought to rely on pattern separation to orthogonalize the representations of similar events. Previously, we reported that a behavioral index of pattern separation was correlated with activity in the hippocampus (dentate gyrus, CA3) and with integrity of the perforant path, which provides input to the hippocampus. If the hippocampus operates as part of a broader neural network, however, pattern separation would likely also relate to integrity of limbic tracts (fornix, cingulum bundle, and uncinate fasciculus) that connect the hippocampus to distributed brain regions. In this study, healthy adults (20-89 years) underwent diffusion tensor imaging and completed the Behavioral Pattern Separation Task-Object Version (BPS-O) and Rey Auditory Verbal Learning Test (RAVLT). After controlling for global effects of brain aging, exploratory skeleton-wise and targeted tractography analyses revealed that fornix integrity (fractional anisotropy, mean diffusivity, and radial diffusivity; but not mode) was significantly related to pattern separation (measured using BPS-O and RAVLT tasks), but not to recognition memory. These data suggest that hippocampal disconnection, via individual- and age-related differences in limbic tract integrity, contributes to pattern separation performance. Extending our earlier work, these results also support the notion that pattern separation relies on broad neural networks interconnecting the hippocampus

Potential and implications of sustainability action plans: lessons from the Greater Middlehaven Regeneration Project

Purpose – Sustainability action plans are emerging as a management tool to facilitate the delivery of sustainability objectives which are planned, measured and achievable in practice. The purpose of this paper is to explore the potential to support an integrated approach to delivering sustainability across the phases of a construction project. A holistic approach to sustainability is promoted which aims to be understandable, managed and aligned with available sustainability assessment methods. Design/methodology/approach – The application of a sustainability action plan is explored in the Greater Middlehaven Regeneration Project (UK). Six key stakeholders were interviewed to consider the rational of its application, structure, role of sustainability assessment and contribution to project development and delivery. Two workshops involving practitioners and experts in sustainable construction explored the implications for the wider context. Findings – A framework around which sustainability can be managed through a series of integrated tailored action plans applied across each project phase was highlighted. Clear benefits were presented in facilitating the sharing of knowledge, communicating aspirations and in providing leadership to project members. Research limitations/implications – The case study enjoys a supportive environment to embed best practice and thus full appreciation of potential barriers to implementation in other contexts was not possible. Practical implications – The research illustrates the need to promote a common sustainability legacy across the project phases and highlights the role of a sustainability action plan in facilitating this consistency. Originality/value – A holistic approach founded on an understandable philosophy remains innovative in practice and explored are its value and implications. </jats:sec

Recognition Memory Dysfunction Relates to Hippocampal Subfield Volume: A Study of Cognitively Normal and Mildly Impaired Older Adults.

ObjectivesThe current study examined recognition memory dysfunction and its neuroanatomical substrates in cognitively normal older adults and those diagnosed with mild cognitive impairment (MCI).MethodsParticipants completed the Mnemonic Similarity Task, which provides simultaneous measures of recognition memory and mnemonic discrimination. They also underwent structural neuroimaging to assess volume of medial temporal cortex and hippocampal subfields.ResultsAs expected, individuals diagnosed with MCI had significantly worse recognition memory performance and reduced volume across medial temporal cortex and hippocampal subfields relative to cognitively normal older adults. After controlling for diagnostic group differences, however, recognition memory was significantly related to whole hippocampus volume, and to volume of the dentate gyrus/CA3 subfield in particular. Recognition memory was also related to mnemonic discrimination, a fundamental component of episodic memory that has previously been linked to dentate gyrus/CA3 structure and function.DiscussionResults reveal that hippocampal subfield volume is sensitive to individual differences in recognition memory in older adults independent of clinical diagnosis. This supports the notion that episodic memory declines along a continuum within this age group, not just between diagnostic groups

Increased prevalence of precancerous changes in relatives of gastric cancer patients: critical role of H. pylori

Background &#38; Aims:Helicobacter pylori is believed to predispose to gastric cancer by inducing gastric atrophy and hypochlorhydria. First-degree relatives of patients with gastric cancer have an increased risk of developing gastric cancer. The aim of this study was to determine the prevalence of atrophy and hypochlorhydria and their association with H. pylori infection in first-degree relatives of patients with gastric cancer. Methods:H. pylori status, gastric secretory function, and gastric histology were studied in 100 first-degree relatives of patients with noncardia gastric cancer and compared with those of controls with no family history of this cancer. Results: Compared with healthy controls, relatives of patients with gastric cancer had a higher prevalence of hypochlorhydria (27% vs. 3%) but a similar prevalence of H. pylori infection (63% vs. 64%). Relatives of cancer patients also had a higher prevalence of atrophy (34%) than patients with nonulcer dyspepsia (5%) matched for H. pylori prevalence. Among the relatives of cancer patients, the prevalence of atrophy and hypochlorhydria was increased only in those with evidence of H. pylori infection, was greater in relatives of patients with familial cancer than in relatives of sporadic cancer index patients, and increased with age. Eradication of H. pylori infection produced resolution of the gastric inflammation in each subject and resolution of hypochlorhydria and atrophy in 50% of the subjects. Conclusions: Relatives of patients with gastric cancer have an increased prevalence of precancerous gastric abnormalities, but this increase is confined to those with H. pylori infection. Consequently, prophylactic eradication of the infection should be offered to such subjects

Neural substrates of mnemonic discrimination: A whole-brain fMRI investigation.

IntroductionA fundamental component of episodic memory is the ability to differentiate new and highly similar events from previously encountered events. Numerous functional magnetic resonance imaging (fMRI) studies have identified hippocampal involvement in this type of mnemonic discrimination (MD), but few studies have assessed MD-related activity in regions beyond the hippocampus. Therefore, the current fMRI study examined whole-brain activity in healthy young adults during successful discrimination of the test phase of the Mnemonic Similarity Task.MethodIn the study phase, participants made "indoor"/"outdoor" judgments to a series of objects. In the test phase, they made "old"/"new" judgments to a series of probe objects that were either repetitions from the memory set (targets), similar to objects in the memory set (lures), or novel. We assessed hippocampal and whole-brain activity consistent with MD using a step function to identify where activity to targets differed from activity to lures with varying degrees of similarity to targets (high, low), responding to them as if they were novel.ResultsResults revealed that the hippocampus and occipital cortex exhibited differential activity to repeated stimuli relative to even highly similar stimuli, but only hippocampal activity predicted discrimination performance.ConclusionsThese findings are consistent with the notion that successful MD is supported by the hippocampus, with auxiliary processes supported by cortex (e.g., perceptual discrimination)

Completing the picture of the Roper resonance

We employ a continuum approach to the three valence-quark bound-state problem in relativistic quantum field theory to predict a range of properties of the proton's radial excitation and thereby unify them with those of numerous other hadrons. Our analysis indicates that the nucleon's first radial excitation is the Roper resonance. It consists of a core of three dressed-quarks, which expresses its valence-quark content and whose charge radius is 80% larger than the proton analogue. That core is complemented by a meson cloud, which reduces the observed Roper mass by roughly 20%. The meson cloud materially affects long-wavelength characteristics of the Roper electroproduction amplitudes but the quark core is revealed to probes with $Q^2 \gtrsim 3 m_N^2$.Comment: 6 pages, 3 figure