Search results for "PLASTICITY"
showing 10 items of 765 documents
Functional relevance of cross-modal plasticity in blind humans
1997
Functional imaging studies of people who were blind from an early age have revealed that their primary visual cortex can be activated by Braille reading and other tactile discrimination tasks1. Other studies have also shown that visual cortical areas can be activated by somatosensory input in blind subjects but not those with sight2,3,4,5,6,7. The significance of this cross-modal plasticity is unclear, however, as it is not known whether the visual cortex can process somatosensory information in a functionally relevant way. To address this issue, we used transcranial magnetic stimulation to disrupt the function of different cortical areas in people who were blind from an early age as they i…
Brain Function and Upper Limb Outcome in Stroke: A Cross-Sectional fMRI Study
2015
Objective The nature of changes in brain activation related to good recovery of arm function after stroke is still unclear. While the notion that this is a reflection of neuronal plasticity has gained much support, confounding by compensatory strategies cannot be ruled out. We address this issue by comparing brain activity in recovered patients 6 months after stroke with healthy controls. Methods We included 20 patients with upper limb paresis due to ischemic stroke and 15 controls. We measured brain activation during a finger flexion-extension task with functional MRI, and the relationship between brain activation and hand function. Patients exhibited various levels of recovery, but all we…
Are postural responses to backward and forward perturbations processed by different neural circuits?
2013
Item does not contain fulltext Startle pathways may contribute to rapid accomplishment of postural stability. Here we investigate the possible influence of a startling auditory stimulus (SAS) on postural responses. We formulated four specific questions: (1) can a concurrent SAS shorten the onset of automatic postural responses?; and if so (2) is this effect different for forward versus backward perturbations?; (3) does this effect depend on prior knowledge of the perturbation direction?; and (4) is this effect different for low- and high-magnitude perturbations? Balance was perturbed in 11 healthy participants by a movable platform that suddenly translated forward or backward. Each particip…
Modulatory role of the brain-derived neurotrophic factor Val66Met polymorphism on the effects of serious life events on impulsive aggression in borde…
2009
Impulsive aggression belongs to the key features of borderline personality disorder (BPD). In the development of BPD, serious life events are known to play a major role. Acute and chronic stress has been suggested to inhibit hippocampal brain-derived neurotrophic factor (BDNF) synthesis and to mediate neural plasticity in response to adverse social experiences. Recently it has been reported that the frequency of violent suicide attempts is higher in adult suicide attempters reporting severe childhood sexual abuse and carrying the Val(66)Val genotype of the BDNF Val(66)Met polymorphism. In this study we analysed modulating effects of BDNF Val(66)Met polymorphism on the effects of physical ma…
State dependent posterior hippocampal volume increases in patients with major depressive disorder.
2011
Abstract Background The hippocampal formation has been implicated in etiology and therapy response in major depressive disorder (MDD). However, prospective longitudinal studies investigating volumes in hippocampal subregions and their association with clinical findings are still lacking. Methods Global and regional hippocampal volumes and neuropsychological performance were assessed longitudinally in 15 young patients with unipolar early onset MDD who responded to therapy and 13 matched healthy control subjects. Results Although volumes at baseline did not differ between groups, patients with MDD showed significant posterior hippocampal volume increases during the treatment course (mean obs…
Manual Reaction Times and Brain Dynamics after 'Awake Surgery' of Slow-Growing Tumours Invading the Parietal Area. A Case Report.
2012
International audience; PRIMARY OBJECTIVES: Awake surgeries of slow-growing tumours invading the brain and guided by direct electrical stimulation induce major brain reorganizations accompanied with slight impairments post-operatively. In most cases, these deficits are so slight after a few days that they are often not detectable on classical neuropsychological evaluations. Consequently, this study investigated whether simple visuo-manual reaction time paradigms would sign some level of functional asymmetries between both hemispheres. Importantly, the visual stimulus was located in the saggital plane in order to limit attentional biases and to focus mainly on the inter-hemispheric asymmetry…
Neural Compensation Within the Human Triceps Surae During Prolonged Walking
2011
During human walking, muscle activation strategies are approximately constant across consecutive steps over a short time, but it is unknown whether they are maintained over a longer duration. Prolonged walking may increase tendinous tissue (TT) compliance, which can influence neural activation, but the neural responses of individual muscles have not been investigated. This study investigated the hypothesis that muscle activity is up- or down-regulated in individual triceps surae muscles during prolonged walking. Thirteen healthy subjects walked on a treadmill for 60 min at 4.5 km/h, while triceps surae muscle activity, maximal muscle compound action potentials, and kinematics were recorded…
Cingulo-Insular Structural Alterations Associated with Psychogenic Symptoms, Childhood Abuse and PTSD in Functional Neurological Disorders
2017
Objective Adverse early-life events are predisposing factors for functional neurological disorder (FND) and post-traumatic stress disorder (PTSD). Cingulo-insular regions are implicated in the biology of both conditions and are sites of stress-mediated neuroplasticity. We hypothesised that functional neurological symptoms and the magnitude of childhood abuse would be associated with overlapping anterior cingulate cortex (ACC) and insular volumetric reductions, and that FND and PTSD symptoms would map onto distinct cingulo-insular areas. Methods This within-group voxel-based morphometry study probes volumetric associations with self-report measures of functional neurological symptoms, advers…
Neural drive preservation after detraining following neuromuscular electrical stimulation training
2006
The purpose of the study was to investigate the behaviour of the central nervous system when 5 weeks of neuromuscular electrical stimulation (NMES) training was followed by 5 weeks of detraining. Nineteen males were divided into the neuromuscular electrostimulated group (EG, n=12) and the control group (CG, n=7). The training program consisted of 15 sessions of isometric NMES over a 5-week period. The EG subjects were tested before training (PRE), after 5 weeks of NMES training (POST) and after 5 weeks of detraining (DE) while CG subjects were only tested at PRE and at POST. Soleus (SOL) and gastrocnemii (GAS) maximal H-reflex and M-wave potentials were evoked at rest (i.e., H(max) and M(ma…
FUNCTIONAL EFFECT OF SHORT-TERM IMMOBILIZATION: KINEMATIC CHANGES AND RECOVERY ON REACHING-TO-GRASP
2012
Abstract Although previous investigations agree in showing significant cortical modifications related to short-term limb immobilization, little is known about the functional changes induced by non-use. To address this issue, we studied the kinematic effect of 10 h of hand immobilization. In order to prevent any movement, right handed healthy participants wore on their dominant hand a soft bandage. They were requested to perform the same reaching-to-grasping task immediately after immobilization, 1 day before (baseline 1) and in other two following days without non-use (baseline 2 and baseline 3). While no differences were found among baseline conditions, an increase of the total duration of…