Can the ‘Head-Turning Sign’ Be a Clinical Marker of Alzheimer's Disease?

Aims: To investigate the incidence and severity of the ‘head-turning sign’ (HTS), i.e. turning the head back to the caregiver(s) for help, in patients with various dementias and discuss its clinical specificity in Alzheimer’s disease (AD). Methods: We investigated the incidence and severity of HTS while administering a short cognitive test (the revised Hasegawa Dementia Rating Scale: HDSR) in outpatients with AD [125 patients, including 4 with AD + vascular dementia (VaD)], 8 with amnestic mild cognitive impairment (aMCI), 34 with dementia with Lewy bodies (DLB), 8 with progressive supranuclear palsy (PSP) and 6 with VaD. Results: Significant differences were found among the 5 disease groups in the incidence and severity of HTS, and HDSR scores. Given the significant differences between AD and DLB in post hoc analyses, patients were dichotomized into AD-related (AD and aMCI) and AD-nonrelated (PSP, DLB and VaD) groups. Both incidence (41 vs. 17%, p = 0.002) and severity of HTS (0.80 ± 1.13 vs. 0.21 ± 0.60, p = 0.001) were significantly higher in the AD-related group, while average age and HDSR scores were comparable between both groups. AD-related disease, female gender and low HDSR score contributed significantly to the occurrence and severity of HTS. Conclusions: HTS can be a clinical marker of AD and aMCI, and may represent a type of excuse behavior as well as a sign of dependency on and trust in the caregivers

Calculation of The Band Gap Energy and Study of Cross Luminescence in Alkaline-Earth Dihalide Crystals

The band gap energy as well as the possibility of cross luminescence processes in alkaline-earth dihalide crystals have been calculated using the ab initio Perturbed-Ion (PI) model. The gap is calculated in several ways: as a difference between one-electron energy eigenvalues and as a difference between total energies of appropriate electronic states of the crystal, both at the HF level and with inclusion of Coulomb correlation effects. In order to study the possibility of ocurrence of cross luminescence in these materials, the energy difference between the valence band and the upmost core band for some representative crystals has been calculated. Both calculated band gap energies and cross luminescence predictions compare very well with the available experimental results.Comment: LaTeX file containing 8 pages plus 1 postscript figure. Final version accepted for publication in The Journal of the Physical Society of Japan. It contains a more complete list of references, as well as a more detailed comparison with previous theoretical investigations on the subjec

Plasma microRNAs are Associated with Atrial Fibrillation (the miRhythm Study) and Change After Catheter-ablation

Background: Atrial fibrillation (AF) is the most common dysrhythmia in the U.S. and Europe. Few biomarkers exist to identify individuals at risk for AF. Cardiac microRNAs (miRNAs) have been implicated in susceptibility to AF and are detectable in the circulation. Nevertheless, data are limited on how circulating levels of miRNAs relate to AF or change over time after catheter- ablation. Methods: In 211 miRhythm participants (112 with paroxysmal or persistent AF; 99 without AF), we quantified plasma expression of 86 miRNAs associated with cardiac remodeling or disease by high-throughput quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). We used qRT-PCR to examine change in plasma miRNA expression from baseline to 1-month after ablation in 47 participants. We also quantified expression of the 20 most variable miRNAs in atrial tissue in 31 participants undergoing cardiac surgery. Results: The mean age of the miRhythm cohort was 59 years and 58% of participants were men. 21 miRNAs differed significantly between participants with AF and those with no AF in regression models adjusting for known AF risk factors (p value of ≤ 0.0006). Several miRNAs associated with AF, including miR-21, miR-29a, miR-122, miR-150, miR-320, and miR-92a, regulate expression of genes implicated in the pathogenesis of AF. Levels of 33 miRNAs, including 14 associated with AF, changed significantly between baseline and 1-month after catheter ablation (p value of ≤ 0.0006). Although all AF-related plasma miRNAs were expressed in atrial tissue, only miR-21 and miR-411 differed significantly with respect to preoperative AF status. Conclusions: Plasma levels of miRNAs associated with heart disease and cardiac remodeling were related to AF and changed after catheter-ablation. Our study suggests that AF has a unique circulating miRNA profile and that this profile is influenced by catheter-ablation

Neural Aspects of Sentence Comprehension: Syntactic Complexity, Reversibility, and Reanalysis

Broca's area is preferentially activated by reversible sentences with complex syntax, but various linguistic factors may be responsible for this finding, including syntactic movement, working-memory demands, and post hoc reanalysis. To distinguish between these, we tested the interaction of syntactic complexity and semantic reversibility in a functional magnetic resonance imaging study of sentence–picture matching. During auditory comprehension, semantic reversibility induced selective activation throughout the left perisylvian language network. In contrast, syntactic complexity (object-embedded vs. subject-embedded relative clauses) within reversible sentences engaged only the left inferior frontal gyrus (LIFG) and left precentral gyrus. Within irreversible sentences, only the LIFG was sensitive to syntactic complexity, confirming a unique role for this region in syntactic processing. Nonetheless, larger effects of reversibility itself occurred in the same regions, suggesting that full syntactic parsing may be a nonautomatic process applied as needed. Complex reversible sentences also induced enhanced signals in LIFG and left precentral regions on subsequent picture selection, but with additional recruitment of the right hemisphere homolog area (right inferior frontal gyrus) as well, suggesting that post hoc reanalysis of sentence structure, compared with initial comprehension, engages an overlapping but larger network of brain regions. These dissociable effects may offer a basis for studying the reorganization of receptive language function after brain damage

Syntax

Syntax refers to the process that governs the word order structure of sentences in a given language. A number of functional imaging studies and lesion-symptom mappings for stroke patients have demonstrated the importance of the left inferior frontal gyrus and its connection to temporal regions for syntactic abilities. By contrast, there are a limited number of studies that have examined language function including syntactic processing of patients undergoing neurosurgical procedures. Some studies have suggested that patients with lesions such as glioma in the left inferior frontal gyrus show deficits in syntactic processing, and the connectivity between the left inferior frontal gyrus and other brain regions is key factor for preserving syntactic abilities of such patients. Recent studies have addressed intraoperative stimulation mapping for syntactic functions using sentence generation tasks, beyond the standard mapping tasks that usually involve single words. While sentence-level stimulation mapping can be performed, it is currently unclear whether or not preserving those sites are critical for syntactic abilities for patients undergoing resection. Surgical resections of the frontal operculum have been shown to be possible without significant postoperative aphasia. Preserved syntactic abilities after the tumor resection in the left inferior frontal gyrus may be due to the postoperative reorganization