Search results for "Motor performance"
showing 10 items of 378 documents
Shifts in Key Time Points and Strategies for a Multisegment Motor Task in Healthy Aging Subjects
2018
International audience; In this study, we compared key temporal points in the whole body pointing movement of healthy aging and young subjects. During this movement, subject leans forward from a standing position to reach a target. As it involves forward inclination of the trunk, the movement creates a risk for falling. We examined two strategic time points during the task-first, the crossover point where the velocity of the center of mass (CoM) in the vertical dimension outstripped the velocity in the anteroposterior dimension and secondly, the time to peak of the CoM velocity profile. Transitions to stabilizing postures occur at these time points. They both occurred earlier in aging subje…
Motor speed and lower extremity strength as predictors of fall-related bone fractures in elderly individuals.
2006
Background and aims: The purpose of this prospective population-based study was to examine the combined effects of motor speed and knee extension strength on risk of fall-related bone fractures in elderly individuals over a 10-year period. Methods: Participants were 307 men and women aged 75 or 80 years at baseline, who visited the research laboratory at the University of Jyvaskyla, Finland. Multi-choice motor speed tests and maximal isometric knee extension strength tests were carried out at baseline. Information on fractures was collected from hospital and health center records. The presence of impairment was defined as a score in the lowest tertile of sex- and age-stratified distribution…
Practice-Related Improvements in Postural Control During Rapid Arm Movement in Older Adults: A Preliminary Study
2012
International audience; Background. Postural control associated with self-paced movement is critical for balance in older adults. The present study aimed to investigate the effects of a virtual reality based program on the postural control associated with rapid arm movement in this population. Methods. From an upright standing position, participants performed rapid arm raising movements toward a target. Practice-related changes were assessed by pre- and posttest comparisons of hand kinematics and center of pressure displacement parameters measured in a training group (mean age: 71.50 +/- 2.67 years, n = 8) and a control group (mean age: 72.87 +/- 3.09 years, n = 8). Training group participa…
Postural balance and its sensory-motor correlates in 75-year-old men and women: a cross-national comparative study.
1996
Background. There are no earlier cross-national comparative studies analyzing the functioning of the posture control mechanisms and its sensory-motor correlates in elderly subjects. We investigated whether there are differences in balance between elderly subjects living in different geographical areas, and analyzed the sensory-motor associates of balance in men and women separately. Method. Using a force platform method, the functioning of the posture control system under three standardized conditions (normal standing, eyes open; normal standing, eyes closed; and tandem standing, eyes open) was studied among samples of 75-year-old residents in three Nordic localities, namely Glostrup in Den…
Comparison of motor strategies in sit-to-stand and back-to-sit motions between healthy and Alzheimer’s disease elderly subjects
2005
We studied the kinematics of shoulder displacement during sit-to-stand and back-to-sit in 6 healthy elderly subjects and six elderly subjects with mild to moderate Alzheimer's disease in order to elucidate the impact of Alzheimer's disease on motor planning and control processes. During sit-to-stand, Alzheimer's disease subjects reduced their forward displacement and started their upward displacement earlier than healthy elderly subjects. Furthermore, shoulder path curvatures were more pronounced for upward compared with downward displacement in healthy elderly group, in contrast with Alzheimer's disease group. Temporal analysis found that: 1) for both groups, profiles of velocity of sit-to…
Mobility performance and its sensory, psychomotor and musculoskeletal determinants from age 75 to age 80.
2010
Background and aims: Prospective studies on the simultaneous effects of multiple determinants on objectively assessed mobility are few. The aim of this study was to analyse mobility performance, its stability and sensory, psychomotor and musculoskeletal determinants in an older population from age 75 to age 80. Methods: Sixty-three men and 121 women aged 75 participated at baseline and, five years later, in the follow-up phase of this population-based prospective study. Maximal walking speed and step-mounting height were assessed at baseline and follow-up. Maximal isometric knee extension strength, standing balance on force platform, reaction time, visual acuity and limitations in range of …
Conserved role of Ras-GEFs in promoting aging: from yeast to mice
2011
RasGRF1 is a Ras-guanine nucleotide exchange factor implicated in a variety of physiological processes including learning and memory and glucose homeostasis. To determine the role of RASGRF1 in aging, lifespan and metabolic parameters were analyzed in aged RasGrf1(-/-) mice. We observed that mice deficient for RasGrf1(-/-) display an increase in average and most importantly, in maximal lifespan (20% higher than controls). This was not due to the role of Ras in cancer because tumor-free survival was also enhanced in these animals. Aged RasGrf1(-/-) displayed better motor coordination than control mice. Protection against oxidative stress was similarly preserved in old RasGrf1(-/-). IGF-I lev…
Co-registering kinematics and evoked related potentials during visually guided reach-to-grasp movements.
2013
Background:In non-human primates grasp-related sensorimotor transformations are accomplished in a circuit involving the anterior intraparietal sulcus (area AIP) and both the ventral and the dorsal sectors of the premotor cortex (vPMC and dPMC, respectively). Although a human homologue of such a circuit has been identified, the time course of activation of these cortical areas and how such activity relates to specific kinematic events has yet to be investigated.Methodology/Principal Findings:We combined kinematic and event-related potential techniques to explicitly test how activity within human grasping-related brain areas is modulated in time. Subjects were requested to reach towards and g…
Fractionation of memory in medial temporal lobe amnesia
2006
We report a comprehensive investigation of the anterograde memory functions of two patients with memory impairments (RH and JC). RH had neuroradiological evidence of apparently selective right-sided hippocampal damage and an intact cognitive profile apart from selective memory impairments. JC, had neuroradiological evidence of bilateral hippocampal damage following anoxia due to cardiac arrest. He had anomic and "executive" difficulties in addition to a global amnesia, suggesting atrophy extending beyond hippocampal regions. Their performance is compared with that of a previously reported hippocampal amnesic patient who showed preserved recollection and familiarity for faces in the context …
Got rhythm… for better and for worse. Cross-modal effects of auditory rhythm on visual word recognition
2013
The present research aimed to investigate whether, as previously observed with pictures, background auditory rhythm would also influence visual word recognition. In a lexical decision task, participants were presented with bisyllabic visual words, segmented into two successive groups of letters, while an irrelevant strongly metric auditory sequence was played in a loop. The first group of letters could either be congruent with the syllabic division of the word (e.g. val in val/se) or not (e.g. va in va/lse). In agreement with the Dynamic Attending Theory (DAT), our results confirmed that the presentation of the correct first syllable on-beat (i.e. in synchrony with a peak of covert attentio…