Entity

Time filter

Source Type


Senna I.,University of Milan Bicocca | Bolognini N.,University of Milan Bicocca | Bolognini N.,Neuropsychological Laboratory | Maravita A.,University of Milan Bicocca
Human Brain Mapping | Year: 2014

Action observation typically induces an online inner simulation of the observed movements. Here we investigate whether action observation merely activates, in the observer, the muscles involved in the observed movement or also muscles that are typically used to achieve the observed action goal. In a first experiment, hand and foot motor areas were stimulated by means of transcranial magnetic stimulation, while participants viewed a typical hand action (grasping) or a nonspecific action (stepping over an object) performed by either a hand or a foot. Hand motor evoked potentials (MEPs) increased for grasping and stepping over actions performed by the hand and for grasping actions performed by the foot. Conversely, foot MEPs increased only for actions performed by the foot. In a second experiment, participants viewed a typical hand action (grasping a pencil) and a typical foot action (pressing a foot-pedal) performed by either a hand or a foot. Again, hand MEPs increased not only during the observation of both actions performed by the hand but also for grasping actions performed by the foot. Foot MEPs increased not only during the observation of grasping and pressing actions performed by the foot but also for pressing actions performed by the hand. This evidence indicates that motor activations by action observation occur also in the muscles typically used to perform the observed action, even when the action is executed by an unusual effector, hence suggesting a double coding of observed actions: a strict somatotopic coding and an action goal coding based on the observer's motor expertise. © 2013 Wiley Periodicals, Inc. Source


Bolognini N.,University of Milan Bicocca | Bolognini N.,Neuropsychological Laboratory | Olgiati E.,University of Milan Bicocca | Maravita A.,University of Milan Bicocca | And 2 more authors.
Pain | Year: 2013

Limb amputation may lead to chronic painful sensations referred to the absent limb, ie phantom limb pain (PLP), which is likely subtended by maladaptive plasticity. The present study investigated whether transcranial direct current stimulation (tDCS), a noninvasive technique of brain stimulation that can modulate neuroplasticity, can reduce PLP. In 2 double-blind, sham-controlled experiments in subjects with unilateral lower or upper limb amputation, we measured the effects of a single session of tDCS (2 mA, 15 min) of the primary motor cortex (M1) and of the posterior parietal cortex (PPC) on PLP, stump pain, nonpainful phantom limb sensations and telescoping. Anodal tDCS of M1 induced a selective short-lasting decrease of PLP, whereas cathodal tDCS of PPC induced a selective short-lasting decrease of nonpainful phantom sensations; stump pain and telescoping were not affected by parietal or by motor tDCS. These findings demonstrate that painful and nonpainful phantom limb sensations are dissociable phenomena. PLP is associated primarily with cortical excitability shifts in the sensorimotor network; increasing excitability in this system by anodal tDCS has an antalgic effect on PLP. Conversely, nonpainful phantom sensations are associated to a hyperexcitation of PPC that can be normalized by cathodal tDCS. This evidence highlights the relationship between the level of excitability of different cortical areas, which underpins maladaptive plasticity following limb amputation and the phenomenology of phantom limb, and it opens up new opportunities for the use of tDCS in the treatment of PLP. © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved. Source


Coubard O.A.,Neuropsychological Laboratory
Frontiers in Aging Neuroscience | Year: 2012

As society ages and frequency of falls increases in older adults, counteracting motor decline is a challenging issue for developed countries. Physical activity based on aerobic and strength training as well as motor activity based on skill learning both help benefit balance and reduce the risk of falls, as assessed by clinical or laboratory measures. However, how such programs influence motor control is a neglected issue. This study examined the effects of fall prevention (FP) training on saccadic control in older adults. Saccades were recorded in 12 participants aged 64-91 years before and after 2.5 months training in FP. Traditional analysis of saccade timing and dynamics was performed together with a quantitative analysis using the LATER model, enabling us to examine the underlying motor control processes. Results indicated that FP reduced the rate of anticipatory and express saccades in inappropriate directions and enhanced that of express saccades in the appropriate direction, resulting in decreased latency and higher left-right symmetry of motor responses. FP reduced within-participant variability of saccade duration, amplitude, and peak velocity. LATER analysis suggested that FP modulates decisional thresholds, extending our knowledge of motor training influence on central motor control. We introduce the Threshold Interval Modulation with Early Release-Rate of rIse Deviation with Early Release (TIMER-RIDER) model to account for the results. Source


Coubard O.A.,Neuropsychological Laboratory
Statistics in Medicine | Year: 2013

Traditional displays of principal component analyses lack readability to discriminate between putative clusters of variables or cases. Here, the author proposes a method that clusterizes and visualizes variables or cases through principal component analyses thus facilitating their analysis. The method displays pre-determined clusters of variables or cases as urchins that each has a soma (the average point) and spines (the individual variables or cases). Through three examples in the field of neuropsychology, the author illustrates how urchins help examine the modularity of cognitive tasks on the one hand and identify groups of healthy versus brain-damaged participants on the other hand. Some of the data used in this article were obtained from the Alzheimer's Disease Neuroimaging Initiative database. The urchin method was implemented in MATLAB, and the source code is available in the Supporting information. Urchins can be useful in biomedical studies to identify distinct phenomena at first glance, each having several measures (clusters of variables) or distinct groups of participants (clusters of cases). © 2013 John Wiley & Sons, Ltd. Source


Coubard O.A.,Neuropsychological Laboratory
Biocybernetics and Biomedical Engineering | Year: 2013

As frequency of falls increases in older adults, understanding how motor training programs counteract motor decline is a challenging issue. This study examined ocular saccades to test the effects of fall prevention (FP) on central motor control of older fallers. Saccades were recorded using a saccadometer in twelve participants aged 64-91 years before and after 2.5-month training in FP. We performed LATER analysis enabling us to examine the changes in motor control. FP decreased saccade latency and increased left-right symmetry of motor responses. LATER analysis showed that FP modulated decisional thresholds extending our knowledge of FP influence on motor control. © 2013 Published by Elsevier Urban & Partner Sp. z o.o. Source

Discover hidden collaborations