Search results for "Spatial"
showing 10 items of 2121 documents
Linking Microstructural Integrity and Motor Cortex Excitability in Multiple Sclerosis
2021
Motor skills are frequently impaired in multiple sclerosis (MS) patients following grey and white matter damage with cortical excitability abnormalities. We applied advanced diffusion imaging with 3T magnetic resonance tomography for neurite orientation dispersion and density imaging (NODDI), as well as diffusion tensor imaging (DTI) in 50 MS patients and 49 age-matched healthy controls to quantify microstructural integrity of the motor system. To assess excitability, we determined resting motor thresholds using non-invasive transcranial magnetic stimulation. As measures of cognitive-motor performance, we conducted neuropsychological assessments including the Nine-Hole Peg Test, Trail Makin…
rTMS evidence of different delay and decision processes in a fronto-parietal neuronal network activated during spatial working memory.
2003
The existence of a specific and widely distributed network for spatial working memory (WM) in humans, involving the posterior parietal cortex and the prefrontal cortex, is supported by a number of neuroimaging studies. We used a repetitive transcranial magnetic stimulation (rTMS) approach to investigate the temporal dynamics and the reciprocal interactions of the different areas of the parieto-frontal network in normal subjects performing a spatial WM task, with the aim to compare neural activity of the different areas in the delay and decision phases of the task. Trains of rTMS at 25 Hz were delivered over the posterior parietal cortex (PPC), the premotor cortex (SFG) and the dorsolateral …
Far Space Remapping by Tool Use: A rTMS Study Over the Right Posterior Parietal Cortex
2015
Abstract Background In previous studies, rTMS has been successfully employed to interfere with the right posterior parietal cortex (rPPC) inducing neglect-like behavior in healthy subjects. Several studies have shown that the use of tools can modulate the boundaries between near and far space: indeed when far space is reached by the stick, far space can be remapped as near. Objective The aim of the present study was to investigate whether once that rTMS on the rPPC has selectively induced neglect-like bias in the near space (but not in the far space), neglect can appears also in the far space when the subjects used a tool to perform the task. Methods Fifteen right-handed healthy subjects ex…
Physical activity, aerobic fitness, and brain white matter : Their role for executive functions in adolescence
2020
Highlights • Aerobic fitness level, but not physical activity, is related to white matter properties in the brain. • The relation between physical activity and working memory is moderated by fractional anisotropy (FA) of the corpus callosum. • The FA of the corpus callosum and superior corona radiata moderates the relation between aerobic fitness and working memory.
Contrasting parental roles shape sex differences in poison frog space use but not navigational performance
2022
Sex differences in vertebrate spatial abilities are typically interpreted under the adaptive specialization hypothesis, which posits that male reproductive success is linked to larger home ranges and better navigational skills. The androgen spillover hypothesis counters that enhanced male spatial performance may be a byproduct of higher androgen levels. Animal groups that include species where females are expected to outperform males based on life-history traits are key for disentangling these hypotheses. We investigated the association between sex differences in reproductive strategies, spatial behavior, and androgen levels in three species of poison frogs. We tracked individuals in natura…
Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950–2019: a…
2020
Background Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian…
Spatio-temporal behaviour of five picophytoplankton populations in Tyrrhe- nian Sea: Model and data
2014
Recent works presented detailed analyses of spatio-temporal dynamics in marine ecosystems, reproducing real vertical distributions of phytoplankton biomass. These study however do not take into account the changes in environmental variables. On the contrary, seasonal variations can influence considerably the primary production, i.e. phytoplankton biomass, in marine ecosystems, determining significative consequences in the whole food chain, in particular fish species, whose growth is mainly explained by seasonal changes in the chlorophyll concentration, a marker of phytoplankton species. Here we present a one-dimensional reaction-diffusion-taxis model to describe the spatio-temporal dynamics…
Reaction-diffusion-taxis model for spatio-temporal dynamics of five picophytoplankton populations
2014
Recently new models were devised to study spatio-temporal dynamics of phytoplankton populations in view of obtaining more precise predictions of the vertical biomass distributions in marine ecosystems. These studies can be crucial from the point of view of shery. Indeed the abundance of fi sh species is strictly connected with primary production, i.e. phytoplankton biomass, responsible for chlorophyll concentration. In this work a one-dimensional deterministic reaction-di ffusion-taxis model is used to reproduce the spatio-temporal dynamics, along a water column, of five picophytoplankton populations sampled in a real ecosystem. In our analysis, to better reproduce the spatio-temporal behav…
Growth dynamics and space in Brazil
2003
The authors bring together two strands of the empirical literature and analyze the geography of the regional economic performance of the states of the Brazilian Federation from 1939 to 1998. Using tools from spatial statistics, they examine the spatial dependence of regional per capita income in Brazil during the past six decades. They also examine the role of geography in explaining economic growth patterns using intradistribution dynamic tools based on Markov transition matrices and stochastic kernels in a discrete and a continuous framework. The analyses reveal the existence of two spatial clusters in Brazil, a low-income cluster in the northeast and a high-income cluster in the southea…
Enforcing mobile security with location-aware role-based access control
2013
This paper describes how location-aware role-based access control RBAC can be implemented on top of the Geospatial eXtensible Access Control Markup Language GeoXACML. It furthermore sketches how spatial separation of duty constraints both static and dynamic can be implemented using GeoXACML on top of the XACML RBAC profile. The solution uses physical addressing of geographical locations, which facilitates easy deployment of authorisation profiles to the mobile device. Location-aware RBAC can be used to implement location-dependent access control and also other security enhancing solutions on mobile devices, such as location-dependent device locking, firewall, intrusion prevention or payment…