Apports de l'imagerie du tenseur de diffusion dans CADASIL

PARIS-BIUM (751062103) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

La dyscalculie développementale, un trouble primaire de la perception des nombres

Nicolas Molko, Anna Wilson, Stanislas Dehaene -Die Rechenschwäche, eine frühzeitige Störung bei der Wahrnehmung von Zahlen. Kinder, die ansonsten über eine normale Intelligenz verfügen, vermögen es nicht, so einfache Rechenaufgaben zu lösen, wie z. B. "sieben minus drei“. Andere wiederum sind unfähig, zwischen zwei Zahlen zu unterscheiden und herauszufinden, wer größer als die andere ist, oder können nicht kleine Mengen diskriminieren, auch wenn sie nur vor zwei oder drei Objekten sitzen. Dieser Mangel heißt "Entwicklungs-Rechenschwäche ”. Sie kann mit Dyslexie verglichen werden. Wie die Dyslexie kann die Entwicklungs-Rechenschwäche bei Kindern auftreten, deren Intelligenz, Umfeld und Erziehung normal sind. Die Entwicklungs-Rechenschwäche kann auch mit anderen kognitiven Mängeln verbunden sein (raumvisuellen Mängel, Aufmerksamkeitsstörung, usw…).Nicolas Molko, Anna Wilson, Stanislas Dehaene Developmental dyscalculia, a primary disorder in the perception of numbers Some children, with otherwise normal intelligence, fails to solve easy calculation, as simple as 7-3. Others don’t manage to choose between two numbers which one is the greater one or cannot discriminate small quantity, even when they are facing only two or three objects. This disorder is called developmental dyscalculia. It can be compared to dyslexia, a learning disability of reading. Similarly to dyslexia, developmental dyscalculia can occur in children with otherwise normal IQ, environment and education. Developmental dyscalculia can be also associated to other cognitive deficits (visuo-spatial deficits, attention disorders, etc.Des enfants, possédant par ailleurs une intelligence normale, ne parviennent pas à résoudre des calculs simples, aussi simple que «sept moins trois» par exemple. D’autres ne parviennent pas, entre deux nombres, à choisir lequel est plus grand que l’autre, ou ne peuvent pas discriminer de petites quantités même quand ils sont face à deux ou trois objets. Ce désordre est dénommé «dyscalculie développementale». Elle peut être comparée à la dyslexie, trouble de l’apprentissage de la lecture. Comme la dyslexie, la dyscalculie développementale peut apparaître chez des enfants d’intelligence, d’environnement et d’éducation normales. La dyscalculie développementale peut également être associée à d’autres déficits cognitifs (déficits spatiovisuels, problèmes d’attention, etc.)Nicolas Molko, Anna Wilson, Stanislas Dehaene -Trastornos en el aprendizaje del cálculo, un desorden primario de la percepción de los números. Ciertos niños, que por otra parte poseen una inteligencia normal, no consiguen resolver cálculos sencillos, tan sencillos como "de tres a siete"por ejemplo. Otros no consiguen escoger entre dos números cuál es mayor que otro, o no pueden discriminar pequeñas cantidades incluso cuando están frente a dos o tres objetos. Este desorden del aprendizaje del cálculo puede compararse con la dislexia, disturbio del aprendizaje de la lectura. Como la dislexia, puede aparecer en niños de inteligencia, entorno y educación normales. Este fenómeno también puede ir asociado a otros déficit cognoscitivos (déficit espaciovisuales, problemas de atención, etc).Molko Nicolas, Wilson Anna, Dehaene Stanislas. La dyscalculie développementale, un trouble primaire de la perception des nombres. In: Revue française de pédagogie, volume 152, 2005. pp. 41-47

La méningite à cryptocoque chez le patient adulte non infecté par le VIH

TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

Brain structure predicts the learning of foreign speech sounds.

International audiencePrevious work has shown a relationship between parietal lobe anatomy and nonnative speech sound learning. We scanned a new group of phonetic learners using structural magnetic resonance imaging and diffusion tensor imaging. Voxel-based morphometry indicated higher white matter (WM) density in left Heschl's gyrus (HG) in faster compared with slower learners, and manual segmentation of this structure confirmed that the WM volume of left HG is larger in the former compared with the latter group. This finding was replicated in a reanalysis of the original groups tested in Golestani and others (2002, Anatomical correlates of learning novel speech sounds. Neuron 35:997-1010). We also found that faster learners have a greater asymmetry (left > right) in parietal lobe volumes than slower learners and that the right insula and HG are more superiorly located in slower compared with faster learners. These results suggest that left auditory cortex WM anatomy, which likely reflects auditory processing efficiency, partly predicts individual differences in an aspect of language learning that relies on rapid temporal processing. It also appears that a global displacement of components of a right hemispheric language network, possibly reflecting individual differences in the functional anatomy and lateralization of language processing, is predictive of speech sound learning

Monitoring disease progression in CADASIL with diffusion magnetic resonance imaging: a study with whole brain histogram analysis.

International audienceBACKGROUND AND PURPOSE: In cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a large increase in water diffusion has been found both inside and outside the cerebral lesions as detected on conventional MRI. The aim of the present study was to assess the sensitivity of diffusion tensor imaging for monitoring the progression of cerebral tissue damage during the course of CADASIL. METHODS: With the use of diffusion tensor imaging, whole brain trace of the diffusion tensor [Trace(D)] histograms were obtained in 22 CADASIL patients and 12 age-matched controls at baseline, in 14 patients after a mean delay of 21 months, and in 5 controls after a mean delay of 29 months. Parameters derived from these histograms (mean value, peak height, and peak location) were analyzed at baseline and during the follow-up. RESULTS: At baseline, all the histogram parameters differed between patients and controls and were found to be significantly correlated with both the Mini-Mental State Examination score and Rankin Scale score in the patient group. The follow-up study showed a decrease in the peak height associated with an increase in the mean value of whole brain Trace(D) histograms in the 14 CADASIL patients scanned twice. The diffusion changes appeared larger in the patients whose Rankin score increased during the study period. CONCLUSIONS: These results suggest that the measurement of water diffusion over time is a sensitive marker for the progression of tissue damage in the brain. Thus, quantitative diffusion MRI can be used to monitor disease progression in CADASIL and possibly in other types of small-vessel brain disorders

Functional and structural alterations of the intraparietal sulcus in a developmental dyscalculia of genetic origin.

International audienceCognitive theories of numerical representation suggest that understanding of numerical quantities is driven by a magnitude representation associated with the intraparietal sulcus and possibly under genetic control. The aim of this study was to investigate, using fMRI and structural imaging, the interaction between the abnormal development of numerical representation in an X-linked condition, Turner syndrome (TS), and the development of the intraparietal sulcus. fMRI during exact and approximate calculation in TS showed an abnormal modulation of intraparietal activations as a function of number size. Morphological analysis revealed an abnormal length, depth, and sulcal geometry of the right intraparietal sulcus, suggesting an important disorganization of this region in TS. Thus, a genetic form of developmental dyscalculia can be related to both functional and structural anomalies of the right intraparietal sulcus, suggesting a crucial role of this region in the development of arithmetic abilities

Longitudinal diffusion changes in cerebral hemispheres after MCA infarcts.

International audienceDiffusion tensor imaging can be used in vivo to assess the longitudinal and regional microstructural changes occurring after middle cerebral artery (MCA) infarcts in humans. Nine patients were investigated 1 week (D7), 1 (M1), 3 (M3), and 6 months (M6) after the occurrence of an isolated MCA infarction. First, an overall analysis was performed using histograms of mean diffusivity (MD) and fractional anisotropy (FA) in each hemisphere. Thereafter, the regional pattern of diffusion changes was investigated voxel by voxel with statistical parametric mapping 99. In the hemisphere ipsilateral to the infarction, histogram analysis revealed a significant decrease in FA between D7 and M6 associated with a progressive increase in MD from D7 to M3. Remote from the MCA territory, the voxel by voxel analyses detected a significant increase in MD within the thalamus at M3 and M6 and a reduction in FA along the pyramidal tract at M6. In the contralateral hemisphere, between D7 and M6, a significant hemispheric atrophy was observed in association with a global reduction in anisotropy, in the absence of distinctive regional diffusion changes. These results suggest that micro- and macrostructural tissue modifications can be detected with diffusion tensor imaging in regions remote from the ischemic area in both hemispheres