Search results for "Magnetic Resonance imaging"
showing 10 items of 2036 documents
Differential effects of age on subcomponents of response inhibition.
2013
Inhibitory deficits contribute to cognitive decline in the aging brain. Separating subcomponents of response inhibition may help to resolve contradictions in the existing literature. A total of 49 healthy participants underwent functional magnetic resonance imaging (fMRI) while performing a Go/no-go-, a Simon-, and a Stop-signal task. Regression analyses were conducted to identify correlations of age and activation patterns. Imaging results revealed a differential effect of age on subcomponents of response inhibition. In a simple Go/no-go task (no spatial discrimination), aging was associated with increased activation of the core inhibitory network and parietal areas. In the Simon task, whi…
Towards a unified analysis of cerebellum maturation and aging across the entire lifespan: A MRI analysis
2021
[EN] Previous literature about the structural characterization of the human cerebellum is related to the context of a specific pathology or focused in a restricted age range. In fact, studies about the cerebellum maturation across the lifespan are scarce and most of them considered the cerebellum as a whole without investigating each lobule. This lack of study can be explained by the lack of both accurate segmentation methods and data availability. Fortunately, during the last years, several cerebellum segmenta- tion methods have been developed and many databases comprising subjects of dif- ferent ages have been made publically available. This fact opens an opportunity window to obtain a mo…
Physical Activity Predicts Population-Level Age-Related Differences in Frontal White Matter
2018
Physical activity has positive effects on brain health and cognitive function throughout the life span. Thus far, few studies have examined the effects of physical activity on white matter microstructure and psychomotor speed within the same, population-based sample (critical if conclusions are to extend to the wider population). Here, using diffusion tensor imaging and a simple reaction time task within a relatively large population-derived sample (N = 399; 18–87 years) from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN), we demonstrate that physical activity mediates the effect of age on white matter integrity, measured with fractional anisotropy. Higher self-reported daily ph…
Ageing‐related changes in the cortical processing of otolith information in humans
2017
Acoustic short tone bursts (STB) trigger ocular and cervical vestibular-evoked myogenic potentials (oVEMPs/cVEMPs) by activating irregular otolith afferents. Simultaneously, STBs introduce an artificial net acceleration signal of otolith origin into the vestibular network. VEMP parameters as diagnostic otolith processing markers have been shown to decline after the age of thirty. To delineate the differential effects of healthy ageing on the cortical vestibular subnetwork processing otolith information, we measured cVEMPs and the differential effects of unilateral STB in three age groups (20-40, 40-60 and 60+; n = 42) using functional neuroimaging. STB evoked responses in the main vestibula…
Altered effective connectivity in drug free schizophrenic patients
2003
The present fMRI study aimed to investigate effective connectivity within a cortical-subcortical-cerebellar information processing network in drug free schizophrenic patients while performing a 2-back working memory task. The finding of enhanced thalamo-cortical and cortico-cortical intrahemispheric connectivity could be interpreted as a compensatory increase of neuronal connection strength consistent with a model of cortical inefficiency in schizophrenic patients. Additionally, the result could be integrated into a model of deficient thalamo-cortical filter functions. Conversely, lower interhemispheric connectivity of the frontal and parietal association cortex appears to be the functional…
Cognitive reserve and cognitive performance of patients with focal frontal lesions.
2016
The Cognitive reserve (CR) hypothesis was put forward to account for the variability in cognitive performance of patients with similar degrees of brain pathology. Compensatory neural activity within the frontal lobes has often been associated with CR. For the first time we investigated the independent effects of two CR proxies, education and NART IQ, on measures of executive function, fluid intelligence, speed of information processing, verbal short term memory (vSTM), naming, and perception in a sample of 86 patients with focal, unilateral frontal lesions and 142 healthy controls. We fitted multiple linear regression models for each of the cognitive measures and found that only NART IQ pre…
The role of the thalamus in amnesia: a tractography, high-resolution MRI and neuropsychological study.
2008
Although it is well established that thalamic lesions may lead to profound amnesia, the precise contribution of thalamic sub-regions to memory remains unclear. In an influential article Aggleton and Brown proposed that recognition memory depends on two processes supported by distinct thalamic and cortical structures. Familiarity is mediated by the mediodorsal (MD) thalamic nucleus and the entorhinal/ perirhinal cortex. Recollection ismediated by the anterior thalamic nucleus (AN), the mamillothalamic tract (MTT) and the hippocampus. The authors also suggested that the lateral dorsal nucleus (LD) may contribute to the thalamic/hippocampus system, thereby implying that the LD may play a role …
The long-term effects of rally driving on spinal pathology
2000
Abstract Objectives. To investigate the consequences of rally driving on lumbar degenerative changes. Background. Vehicular driving is suspected to accelerate disc degeneration through whole-body vibration, leading to back problems. However, in an earlier well-controlled study of lumbar MRI findings in monozygotic twins, significant effects of lifetime driving on disc degeneration were not demonstrated. Another study of machine operators found only long-term exposure to vibration on unsprung seats led to a reduction in disc height. Design. Case-control study comparing rally drivers with population sample. Methods. Eighteen top rally drivers and co-drivers, mean age 43 yrs (SD, 10), voluntee…
Evaluation of the apparent diffusion coefficient in patients with recurrent glioblastoma under treatment with bevacizumab with radiographic pseudores…
2017
Abstract Background Response Assessment in Neuro-Oncology Criteria (RANO), are used to asses response to first-line treatment of glioblastoma (GBM). Differentiation between response and pseudoresponse under treatment with Bevacizumab (BVZ) remains challenging. This study evaluates ADC changes in patients with radiographic pseudoresponse under treatment with (BVZ). Methods Patients (n = 40) with recurrent GBM under-treatment with BVZ underwent MRI before, two and four months after treatment with BVZ. In patients with radiological pseudoresponse (n = 11), ADC analyses were performed. Areas with decreasing T1 contrast enhancement (CE) and FLAIR signal decrease were manually selected and compar…
COMPARISON OF T-1 ESTIMATION TECHNIQUES IN CARDIAC MRI
1994
International audience; Abstract: We have shown that the use of a simple combination of inversion recovery/spin-echo (IR/SE) sequences provides undeniably superior precision in quantitative in vivo myocardium T-1 estimation than the standard multiple spin-echo approach. On a group of 25 healthy subjects, the T-1 dispersion was, respectively, 3.8% for the IR/SE combination and 19.6% for the best SE pair combination. Moreover, repeated measurements were carried out on seven of the volunteers in order to assess T-1 reproducibility. The mean intra-individual T-1 precision was found to be 2.8% for the IR/SE pair and 20.0% for the best SE pair. The in vivo imaging work was supported and corrobora…