Search results for "Spatial"
showing 10 items of 2121 documents
Influence of the contrast sensitivity function on the reaction time
1993
The reaction time (RT) vs spatial frequency (SF) curve is determined, using gratings from 1 to 40 c/deg, at seven different contrast levels between 0.95 and 0.02. The form of the RT/SF function: (a) replicated the inverse of the contrast sensitivity function (CSF) at near threshold contrast levels; (b) behaved differently at higher contrasts, exhibiting two branches at contrast close to 1. The interpretation is that there are two factors determining this function: (1) the transition from the operation of fast transient channels at low SF to the operation of slow sustained channels at high SF, the transition taking place within a narrow SF band close to 6 or 8 c/deg (depending on the subject…
Mid-sagittal plane detection for advanced physiological measurements in brain scans
2019
Objective The process of diagnosing many neurodegenerative diseases, such as Parkinson's and progressive supranuclear palsy, involves the study of brain magnetic resonance imaging (MRI) scans in order to identify and locate morphological markers that can highlight the health status of the subject. A fundamental step in the pre-processing and analysis of MRI scans is the identification of the mid-sagittal plane, which corresponds to the mid-brain and allows a coordinate reference system for the whole MRI scan set. Approach To improve the identification of the mid-sagittal plane we have developed an algorithm in Matlab® based on the k-means clustering function. The results have been compared …
Exogenous t-PA Administration Increases Hippocampal Mature BDNF Levels. Plasmin- or NMDA-Dependent Mechanism?
2014
International audience; Brain-derived neurotrophic factor (BDNF) through TrkB activation is central for brain functioning. Since the demonstration that plasmin is able to process pro-BDNF to mature BDNF and that these two forms have opposite effects on neuronal survival and plasticity, a particular attention has been paid to the link between tissue plasminogen activator (tPA)/plasmin system and BDNF metabolism. However, t-PA via its action on different N-methyl-D-aspartate (NMDA) receptor subunits is also considered as a neuromodulator of glutamatergic transmission. In this context, the aim of our study was to investigate the effect of recombinant (r)t-PA administration on brain BDNF metabo…
The role of pregnenolone sulphate in spatial orientation-acquisition and retention: An interplay between cognitive potentiation and mood regulation
2013
Abstract Neurosteroids can alter neuronal excitability interacting with specific neurotransmitter receptors, thus affecting several functions such as cognition and emotionality. In this study, we investigated, in adult male rats, the effects of the acute administration of pregnenolone-sulfate (PREGS) (10 mg/Kg, s. c.) on cognitive processes using the Can test, a non aversive spatial/visual task which allows the assessment of spatial information-acquisition during the baseline training, and of memory retention in the longitudinal study. Furthermore, on the basis of PREGS pharmacological profile, the modulation of depressive-like behaviour was also evaluated in the forced swim test (FST). Our…
Do mental processes share a domain-general resource?
2010
What determines success and failure in dual-task situations? Many theories propose that the extent to which two activities can be performed concurrently depends on the nature of the information involved in the activities. In particular, verbal and visuospatial activities are thought to be fueled by distinct resources, so that interference occurs between two verbal activities or two visuospatial activities, but little or no interference occurs between verbal and visuospatial activities. The current study examined trade-offs in four dual-task situations in which participants maintained verbal or visuospatial information while concurrently processing either verbal or visuospatial information.…
MOBIlity assessment with modern TEChnology in older patients’ real-life by the General Practitioner: the MOBITEC-GP study protocol
2019
Abstract Background Mobility limitations in older adults are associated with poor clinical outcomes including higher mortality and disability rates. A decline in mobility (including physical function and life-space) is detectable and should be discovered as early as possible, as it can still be stabilized or even reversed in early stages by targeted interventions. General practitioners (GPs) would be in the ideal position to monitor the mobility of their older patients. However, easy-to-use and valid instruments for GPs to conduct mobility assessment in the real-life practice setting are missing. Modern technologies such as the global positioning system (GPS) and inertial measurement units …
Older adults’ activity destinations before and during COVID-19 restrictions: From a variety of activities to mostly physical exercise close to home
2021
The aim was to study various types of older adult's activity destinations (counts, frequency of visitation, and distance from home) in the pre-COVID-19 era, and to study prospectively how COVID-19-related regulations limiting mobility affected these. Using a map-based questionnaire, 75-85-year-old participants reported activity destinations, that is, any destinations for physical exercise, destinations facilitating one's outdoor mobility, and destinations for other activities, which they had visited several times during the past month. At baseline, a variety of activity destinations was reported, but during COVID-19, destinations reported markedly declined in number, they were reported pred…
Emergence and dispersal relative to natal nest in the digger wasp Stizus continuus (Hymenoptera: Crabronidae).
2009
The position of the emerging point has rarely been investigated as a factor possibly affecting the future nest settlement behaviour in Hymenoptera, in particular within nest aggregations. We studied the emergence and dispersion patterns of the digger wasp Stizus continuus. Individuals emerged daily in clumped patterns, possibly revealing a certain synchrony of emergence from the same nests, and protandry appeared both at seasonal and daily level. Differences between the number of females that nested relatively close or far from their emergence holes (EH) were either significant or not, depending on the year, and observed dispersal distances from the natal nests did not differ from those obt…
Linguistic and spatial skills predict early arithmetic development via counting sequence knowledge
2013
Utilizing a longitudinal sample of Finnish children (ages 6-10), two studies examined how early linguistic (spoken vs. written) and spatial skills predict later development of arithmetic, and whether counting sequence knowledge mediates these associations. In Study 1 (N = 1,880), letter knowledge and spatial visualization, measured in kindergarten, predicted the level of arithmetic in first grade, and later growth through third grade. Study 2 (n = 378) further showed that these associations were mediated by counting sequence knowledge measured in first grade. These studies add to the literature by demonstrating the importance of written language for arithmetic development. The findings are …
Spatial Interaction between Neighbouring Counties: Cancer Mortality Data in Valencia (Spain)
1995
The statistical analysis of geographical mortality data has usually been approached via regression models that include appropriate covariates. These models assume stochastic independence of mortality counts for neighbouring sites, a questionable assumption that spatial automodels (Besag, 1974, Journal of the Royal Statistical Society, Series B 36, 192-236) make unnecessary. This paper presents the use of the autopoisson distribution in order to detect spatial interaction between neighbouring sites. If this interaction results in being nonsignificant, the auto-Poisson distribution reduces to a usual Poisson regression model, a particular case of generalized linear models (McCullagh and Nelde…