Paroxysmal eruptions tracked by variations of helium isotopes: inferences from Piton de la Fournaise (La Réunion island).

Helium (He) with its isotopes (3He, 4He) is a key tracer enabling the Earth's mantle and dynamics to be characterized. Enrichment in primordial helium (3He) has been detected in volcanic gases of numerous magmatic systems in different geodynamic settings. Despite past use to monitor volcano-tectonic unrest, temporal 3He/4He variability in volcanic emissions is still poorly constrained. Here, we investigate noble gas chemistry of Piton de la Fournaise hotspot volcano, where temporal fluctuations of 3He/4He in response to the eruptive activity have never been studied. We compare the 3He/4He signature of volcanic gases and fluid inclusions and we highlight analogous evolution of the 3He/4He signature in both during the last decades of eruptive activity (1990-2017), even during the same eruption. We show that the maximum enrichment in 3He is found in magmatic fluids that fed the most voluminous eruptions which culminated in caldera collapse events. We argue that this enrichment in 3He mostly reflects a greater contribution of magmatic fluids from a primitive component of the mantle plume. These results emphasize that He isotopes may provide warnings of increases in deep magmatic contributions that potentially herald paroxysmal eruptions, as documented here at Piton de la Fournaise (2007) and also at Kilauea (2018).

Event-related potential markers of brain changes in preclinical familial Alzheimer disease.

OBJECTIVES: Event-related potentials (ERPs) can reflect differences in brain electrophysiology underlying cognitive functions in brain disorders such as dementia and mild cognitive impairment. To identify individuals at risk for Alzheimer disease (AD) we used high-density ERPs to examine brain physiology in young presymptomatic individuals (average age 34.2 years) who carry the E280A mutation in the presenilin-1 (PSEN1) gene and will go on to develop AD around the age of 45. METHODS: Twenty-one subjects from a Colombian population with familial AD participated: 10 presymptomatic subjects positive for the PSEN1 mutation (carriers) and 11 siblings without the mutation (controls). Subjects performed a visual recognition memory test while 128-channel ERPs were recorded. RESULTS: Despite identical behavioral performance, PSEN1 mutation carriers showed less positivity in frontal regions and more positivity in occipital regions, compared to controls. These differences were more pronounced during the 200-300 msec period. Discriminant analysis at this time interval showed promising sensitivity (72.7%) and specificity (81.8%) of the ERP measures to predict the presence of AD pathology. CONCLUSIONS: Presymptomatic PSEN1 mutation carriers show changes in brain physiology that can be detected by high-density ERPs. The relative differences observed showing greater frontal positivity in controls and greater occipital positivity in carriers indicates that control subjects may use frontally mediated processes to distinguish between studied and unstudied visual items, whereas carriers appear to rely more upon perceptual details of the items to distinguish between them. These findings also demonstrate the potential usefulness of ERP brain correlates as preclinical markers of AD.

Comparación del desempeño neuropsicológico según la edad de inicio en sujetos con enfermedad de Parkinson y parkinsonismo / Comparison of neuropsychological performance according to the age of onset in subjects with parkinson´s disease and parkinsonism

Introducción. La enfermedad de Parkinson (EP) es el trastorno neurodegenerativo más común después de la enfermedad de Alzheimer, y se caracteriza por temblor, bradicinesia, rigidez e inestabilidad postural. El trastorno cognitivo más común es disfunción ejecutiva, aunque también se han informado déficit globales asociados al inicio tardío de la enfermedad. Objetivos. Describir y comparar el desempeño cognitivo en tres grupos con EP y uno con parkinsonismo. Pacientes y métodos. A 175 pacientes con EP idiopática y parkinsonismo se les realizó una valoración neurológica y neuropsicológica. El análisis de datos se hizo comparando resultados de las pruebas para cuatro grupos: tres con EP (edad de inicio: juvenil, del adulto y tardía) y uno con parkinsonismo, y controlando por edad, escolaridad y tiempo de evolución. Resultados. En el grupo conEP juvenil se encontró alteración en el número de intrusiones en memoria verbal; en los de EP del adulto y EP tardía, se encontró alteración en el tiempo en ejecución continua visual. Comparados entre sí los grupos y controlando por edad, las diferencias desaparecieron. El grupo con parkinsonismo obtuvo resultados inferiores a todos los grupos con EP para la mayoría de variables cognitivas y funcionales. Conclusiones. La EP idiopática no sería causante de deterioro cognitivo múltiple, sino de una alteración específica, principalmente en velocidad de procesamiento y evocación de la información. La edad de inicio no sería un factor decisivo en el grado de deterioro del funcionamiento cognitivo; sólo existe un deterioro cognitivo importante en el grupo con parkinsonismo (AU)

Introduction. Parkinson’s disease (PD) is the second most common neurodegenerative disorder after Alzheimer’s disease, and it is characterised by tremor, bradykinesia, rigidity and postural instability. The most frequent cognitive disorder is executive dysfunction, although global deficits associated to late onset of the disease have also been reported. Aims. To describe and to compare cognitive performance in three groups with PD and one with Parkinsonism. Patients and methods. A neurological and neuropsychological evaluation was carried out on 175 patients with idiopathic PD and Parkinsonism. The data analysis was performed by comparing the results of the tests carried out on the four groups: three with PD (age of onset: juvenile, adult and late) and one with Parkinsonism, while controlling for age, schooling and time of progression. Results. In the juvenile PD group, alterations were observed in the number of intrusions in verbal memory; in the adult PD and late PD groups, there were alterations in time in continuous visual execution. These differences disappeared when the groups were compared to each other while also controlling for age. The Parkinsonism group obtained results that were lower than those of all the groups with PD for most of the cognitive and functional variables. Conclusions. Idiopathic PD would not be the cause of multiple cognitive impairment, but of a specific alteration, mainly involving the speed of processing and information recall. Age of onset would not be a decisive factor in the degree of impairment of cognitive functioning; important cognitive impairment was only present in the group with Parkinsonism (AU)

[Comparison of neuropsychological performance according to the age of onset in subjects with Parkinson's disease and Parkinsonism]. / Comparación del desempeño neuropsicológico según la edad de inicio en sujetos con enfermedad de Parkinson y parkinsonismo.

INTRODUCTION: Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease, and it is characterised by tremor, bradykinesia, rigidity and postural instability. The most frequent cognitive disorder is executive dysfunction, although global deficits associated to late onset of the disease have also been reported. AIMS: To describe and to compare cognitive performance in three groups with PD and one with Parkinsonism. PATIENTS AND METHODS: A neurological and neuropsychological evaluation was carried out on 175 patients with idiopathic PD and Parkinsonism. The data analysis was performed by comparing the results of the tests carried out on the four groups: three with PD (age of onset: juvenile, adult and late) and one with Parkinsonism, while controlling for age, schooling and time of progression. RESULTS: In the juvenile PD group, alterations were observed in the number of intrusions in verbal memory; in the adult PD and late PD groups, there were alterations in time in continuous visual execution. These differences disappeared when the groups were compared to each other while also controlling for age. The Parkinsonism group obtained results that were lower than those of all the groups with PD for most of the cognitive and functional variables. CONCLUSIONS: Idiopathic PD would not be the cause of multiple cognitive impairment, but of a specific alteration, mainly involving the speed of processing and information recall. Age of onset would not be a decisive factor in the degree of impairment of cognitive functioning; important cognitive impairment was only present in the group with Parkinsonism.