Abnormal connectivity between the default mode and the visual system underlies the manifestation of visual hallucinations in Parkinson’s disease:A task-based fMRI study

Background: The neural substrates of visual hallucinations remain an enigma, due primarily to the difficulties associated with directly interrogating the brain during hallucinatory episodes. Aims: To delineate the functional patterns of brain network activity and connectivity underlying visual hallucinations in Parkinson’s disease. Methods: In this study, we combined functional magnetic resonance imaging (MRI) with a behavioral task capable of eliciting visual misperceptions, a confirmed surrogate for visual hallucinations, in 35 patients with idiopathic Parkinson’s disease. We then applied an independent component analysis to extract time series information for large-scale neuronal networks that have been previously implicated in the pathophysiology of visual hallucinations. These data were subjected to a task-based functional connectivity analysis, thus providing the first objective description of the neural activity and connectivity during visual hallucinations in patients with Parkinson’s disease. Results: Correct performance of the task was associated with increased activity in primary visual regions; however, during visual misperceptions, this same visual network became actively coupled with the default mode network (DMN). Further, the frequency of misperception errors on the task was positively correlated with the strength of connectivity between these two systems, as well as with decreased activity in the dorsal attention network (DAN), and with impaired connectivity between the DAN and the DMNs, and ventral attention networks. Finally, each of the network abnormalities identified in our analysis were significantly correlated with two independent clinical measures of hallucination severity. Conclusions: Together, these results provide evidence that visual hallucinations are due to increased engagement of the DMN with the primary visual system, and emphasize the role of dysfunctional engagement of attentional networks in the pathophysiology of hallucinations

RHECITAS: citation analysis of French humanities articles

International audienceThe RHECITAS project aims at the analysis of citations in French Humanities and Social Sciences articles using natural language processing techniques. It is based on a corpus of online articles, through the aid of natural language processing tools. The project is funded by TGE-ADONIS (CNRS, French National Research Centre). Although very little research, either theoretical and technical, has been made on such data (most approaches focusing on science publications written in English), we developed two different tools that can automatically a) identify the more important items in a list of references, based on a number of linguistic cues, and b) extract relevant terms associated to a reference. These results show a new angle on citation analysis, both from a linguistic point of view and for practical applications

Changes in structural network topology correlate with severity of hallucinatory behavior in Parkinson's disease

Inefficient integration between bottom-up visual input and higher order visual processing regions is implicated in visual hallucinations in Parkinson's disease (PD). Here, we investigated white matter contributions to this perceptual imbalance hypothesis. Twenty-nine PD patients were assessed for hallucinatory behavior. Hallucination severity was correlated to connectivity strength of the network using the network-based statistic approach. The results showed that hallucination severity was associated with reduced connectivity within a subnetwork that included the majority of the diverse club. This network showed overall greater between-module scores compared with nodes not associated with hallucination severity. Reduced between-module connectivity in the lateral occipital cortex, insula, and pars orbitalis and decreased within-module connectivity in the prefrontal, somatosensory, and primary visual cortices were associated with hallucination severity. Conversely, hallucination severity was associated with increased between- and within-module connectivity in the orbitofrontal and temporal cortex, as well as regions comprising the dorsal attentional and default mode network. These results suggest that hallucination severity is associated with marked alterations in structural network topology with changes in participation along the perceptual hierarchy. This may result in the inefficient transfer of information that gives rise to hallucinations in PD. Author SummaryInefficient integration of information between external stimuli and internal perceptual predictions may lead to misperceptions or visual hallucinations in Parkinson's disease (PD). In this study, we show that hallucinatory behavior in PD patients is associated with marked alterations in structural network topology. Severity of hallucinatory behavior was associated with decreased connectivity in a large subnetwork that included the majority of the diverse club, nodes with a high number of between-module connections. Furthermore, changes in between-module connectivity were found across brain regions involved in visual processing, top-down prediction centers, and endogenous attention, including the occipital, orbitofrontal, and posterior cingulate cortex. Together, these findings suggest that impaired integration across different sides across different perceptual processing regions may result in inefficient transfer of information

Assessing Mathematical School Readiness

Early math skills matter for later formal mathematical performances, academic and professional success. Accordingly, it is important to accurately assess mathematical school readiness (MSR) at the beginning of elementary school. This would help identifying children who are at risk of encountering difficulties in math and then stimulate their acquisition of mathematical skills as soon as possible. In the present study, we present a new test that allows professionals working with children (e.g., teachers, school psychologists, speech therapists, and school doctors) to assess children’s MSR when they enter formal schooling in a simple, rapid and efficient manner. 346 children were assessed at the beginning of 1st Grade (6-to-7-year-olds) with a collective test assessing early mathematical abilities (T1). In addition, children’s math skills were evaluated with classical curriculum math tests at T1 and a year later, in 2nd Grade (T2, 7-to-8-year-olds). After assessing internal consistency, three tasks were retained for the final version of the MSR test. Test performance confirmed to be essentially unidimensional and systematically related to the scores children obtained in classical tests in 1st and 2nd Grade. By using the present MSR test, it is possible to identify pupils at risk of developing low math skills right from the start of formal schooling in 1st Grade. Such a tool is needed, as children’s level in math at school beginning (or school readiness) is known to be foundational for their future academic and professional carrier

Influence of renal replacement modalities on amikacin population pharmacokinetics in critically ill patients on continuous renal replacement therapy

The objective of this study was to describe amikacin pharmacokinetics (PK) in critically ill patients receiving equal doses (30 ml/kg of body weight/h) of continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodiafiltration (CVVHDF). Patients receiving amikacin and undergoing CVVH or CVVHDF were eligible. Population pharmacokinetic analysis and Monte Carlo simulation were undertaken using the Pmetrics software package for R. Sixteen patients (9 undergoing CVVH, 11 undergoing CVVHDF) and 20 sampling intervals were analyzed. A two-compartment linear model best described the data. Patient weight was the only covariate that was associated with drug clearance. The mean +/- standard deviation parameter estimates were 25.2 +/- 17.3 liters for the central volume, 0.89 +/- 1.17 h(-1) for the rate constant for the drug distribution from the central to the peripheral compartment, 2.38 +/- 6.60 h(-1) for the rate constant for the drug distribution from the peripheral to the central compartment, 4.45 +/- 2.35 liters/h for hemodiafiltration clearance, and 4.69 +/- 2.42 liters/h for hemofiltration clearance. Dosing simulations for amikacin supported the use of high dosing regimens (>= 25 mg/kg) and extended intervals (36 to 48 h) for most patients when considering PK/pharmacodynamic (PD) targets of a maximum concentration in plasma (C-max)/MIC ratio of >= 8 and a minimal concentration o

Plant growth-promoting rhizobacteria and root system functioning

The rhizosphere supports the development and activity of a huge and diversified microbial community, including microorganisms capable to promote plant growth. Among the latter, plant growth-promoting rhizobacteria (PGPR) colonize roots of monocots and dicots, and enhance plant growth by direct and indirect mechanisms. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead, mostly, to enhanced lateral root branching and development of root hairs. PGPR also modify root functioning, improve plant nutrition and influence the physiology of the whole plant. Recent results provided first clues as to how PGPR signals could trigger these plant responses. Whether local and/or systemic, the plant molecular pathways involved remain often unknown. From an ecological point of view, it emerged that PGPR form coherent functional groups, whose rhizosphere ecology is influenced by a myriad of abiotic and biotic factors in natural and agricultural soils, and these factors can in turn modulate PGPR effects on roots. In this paper, we address novel knowledge and gaps on PGPR modes of action and signals, and highlight recent progress on the links between plant morphological and physiological effects induced by PGPR. We also show the importance of taking into account the size, diversity, and gene expression patterns of PGPR assemblages in the rhizosphere to better understand their impact on plant growth and functioning. Integrating mechanistic and ecological knowledge on PGPR populations in soil will be a prerequisite to develop novel management strategies for sustainable agriculture

Cognitive Potential and Academic Success in Luxembourg: Use case of the "Test of Cognitive Potential"

The “Test of Cognitive Ability” (“TCP”) is a language-free test of reasoning ability that was created at the heart of the Luxembourg Centre for Educational Testing (LUCET). The TCP was initially developed for children at the age of 10 and can be applied in a group context. Since no advanced language-skills are required in order to take this test, it is perfectly suited not only to serve as a cognitive ability screener in a multi-lingual context, but also to study the relationship of cognitive ability and academic success within a demanding school-system that deals with a very complex mixture of student backgrounds (spoken languages, socioeconomic status, culture, etc.). Using traditional intelligence tests with language-based tasks and instructions could, in this context, result in biased data since maximum performance relies on a good understanding of task requirements. Being language-free, the TCP can help in gaining a more precise understanding of academic performance under different circumstances and prevent wrong conclusions as to the fairness of curricular requirements for different student populations. The present contribution will present the Test of Cognitive Potential and give an overview of how the relationship of cognitive ability and academic success varied within different subpopulations of a Luxembourgish sample of 303 4th graders

Einfluss des Faktors Wortfrequenz auf die satzinterne Großschreibung bei Fünftklässler:innen

Frequenz ist ein vielbeachteter Faktor, wenn es darum geht, zu erklären, warum manche Wörter und Teilbereiche von Wörtern eher fehleranfälliger sind als andere. In regelhaften Bereichen der Orthographie haben viele Studien zudem gezeigt, dass Frequenz einen größeren Einfluss auf Richtigschreibungen haben könnte als regelbasiertes Lernen. Der vorliegende Beitrag nimmt dies zum Ausgangspunkt und untersucht, ob der Faktor der Wortfrequenz in der satzinternen Großschreibung eine Rolle spielt. Die Arbeit umfasst zwei Forschungsfragen: (1) Sagt die Wortfrequenz von Nomen deren Großschreibung voraus, wenn man Konkretheit kontrolliert? und (2) Sagt die Frequenz von Verben und Adjektiven in Bezug auf die Frequenz der entsprechenden Nominalisierungen die Großschreibung letzterer voraus? Für die Untersuchung wurde die Großschreibung von 185 luxemburgischen Fünftklässler:innen in Lücken- und Satzdiktaten analysiert. Die Frequenz wurde aufgrund von drei Korpora berechnet. Die Regressionsanalysen zeigen das frequente Nomen eher großgeschrieben werden als seltene Nomen. Allerdings verschwindet dieser Effekt, wenn der lexikalisch-semantische Typ (Konkreta, Abstrakta, Nominalisierungen) in die Analysen einbezogen wird. Der ausschlaggebende Faktor für die Großschreibung in dieser Studie war schließlich Konkretheit, nicht Frequenz

Hommage à Daniel Morane

Daniel Morane nous a quittés le 21 février dernier après avoir affronté, avec le courage et la lucidité que nous lui connaissions, une pénible maladie. Ami des conservateurs comme des artistes, animateur dévoué de plusieurs sociétés concernant le monde de l’art, il laisse un grand vide. Cet ancien dirigeant de grands magasins et de sociétés bancaires, amateur d’art et collectionneur de longue date, s’était épris de l’estampe, et lorsque des ennuis de santé l’obligèrent à prendre une retraite ..

Taking Language out of the Equation: The Assessment of Basic Math Competence Without Language

While numerical skills are fundamental in modern societies, some estimated 5–7% of children suffer from mathematical learning difficulties (MLD) that need to be assessed early to ensure successful remediation. Universally employable diagnostic tools are yet lacking, as current test batteries for basic mathematics assessment are based on verbal instructions. However, prior research has shown that performance in mathematics assessment is often dependent on the testee's proficiency in the language of instruction which might lead to unfair bias in test scores. Furthermore, language-dependent assessment tools produce results that are not easily comparable across countries. Here we present results of a study that aims to develop tasks allowing to test for basic math competence without relying on verbal instructions or task content. We implemented video and animation-based task instructions on touchscreen devices that require no verbal explanation. We administered these experimental tasks to two samples of children attending the first grade of primary school. One group completed the tasks with verbal instructions while another group received video instructions showing a person successfully completing the task. We assessed task comprehension and usability aspects both directly and indirectly. Our results suggest that the non-verbal instructions were generally well understood as the absence of explicit verbal instructions did not influence task performance. Thus we found that it is possible to assess basic math competence without verbal instructions. It also appeared that in some cases a single word in a verbal instruction can lead to the failure of a task that is successfully completed with non-verbal instruction. However, special care must be taken during task design because on rare occasions non-verbal video instructions fail to convey task instructions as clearly as spoken language and thus the latter do not provide a panacea to non-verbal assessment. Nevertheless, our findings provide an encouraging proof of concept for the further development of non-verbal assessment tools for basic math competence