Search results for "imagin."
showing 10 items of 7170 documents
Mentally represented motor actions in normal aging. I. Age effects on the temporal features of overt and covert execution of actions.
2005
The present study examines the temporal features of overt and covert actions as a function of normal aging. In the first experiment, we tested three motor tasks (walking, sit-stand-sit, arm pointing) that did not imply any particular spatiotemporal constraints, and we compared the duration of their overt and covert execution in three different groups of age (mean ages: 22.5, 66.2 and 73.4 years). We found that the ability of generating motor images did not differentiate elderly subjects from young subjects. Precisely, regarding overt and covert durations, subjects presented similarities for the walking and pointing tasks and dissimilarities for the stand-sit-stand task. Furthermore, the tim…
Mentally represented motor actions in normal agingII. The influence of the gravito-inertial context on the duration of overt and covert arm movements
2007
Here, we address the question of whether normal aging influences action representation by comparing the ability of 14 young (age: 23.6 +/- 2.1 years) and 14 older (age: 70.1 +/- 4.5 years) adults to mentally simulate arm movements under a varying dynamic context. We conducted two experiments in which we experimentally manipulated the gravity and inertial components of arm dynamics: (i) unloaded and loaded vertical arm movements, rotation around the shoulder joint, (ii) unloaded and loaded horizontal arm movements, rotations around the shoulder and elbow joints, in two directions (inertial anisotropy phenomenon). The main findings indicated that imagery ability was equivalent between the two…
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 …
RUPTURE OF A LEFT SINUS OF VALSALVA ANEURYSM INTO THE PULMONARY ARTERY.
2006
Sinus of Valsalva aneurysm is a rare congenital defect and the diagnosis is usually made after it ruptures. Very few cases of non-complicated sinus of Valsalva aneurysm have been published. The anomaly most often involves the right coronary sinus and less frequently the non-coronary sinus. A case with left sinus of Valsalva has not been reported. Since the aortic valve occupies a central position in the base of the heart, rupture of a sinus of Valsalva aneurysm can occur in any of the four heart chambers. Rupture into the pulmonary artery is very rare and is mostly associated with other congenital cardiopathies. ª 2005 The European Society of Cardiology. Published by Elsevier Ltd. All right…