Laure Fernandez
Aix-Marseille University
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Publication
Featured researches published by Laure Fernandez.
Journal of Neurophysiology | 2008
Andrea d'Avella; Laure Fernandez; Alessandro Portone; Francesco Lacquaniti
How the CNS masters the many degrees of freedom of the musculoskeletal system to control goal-directed movements is a long-standing question. We have recently provided support to the hypothesis that the CNS relies on a modular control architecture by showing that the phasic muscle patterns for fast reaching movements in different directions are generated by combinations of a few time-varying muscle synergies: coordinated recruitment of groups of muscles with specific activation profiles. However, natural reaching movements occur at different speeds and require the control of both movement and posture. Thus we have investigated whether muscle synergies also underlie reaching at different speeds as well as the maintenance of stable arm postures. Hand kinematics and shoulder and elbow muscle surface EMGs were recorded in five subjects during reaches to eight targets in the frontal plane at different speeds. We found that the amplitude modulation of three time-invariant synergies captured the variations in the postural muscle patterns at the end of the movement. During movement, three phasic and three tonic time-varying synergies could reconstruct the time-normalized muscle pattern in all conditions. Phasic synergies were modulated in both amplitude and timing by direction and speed. Tonic synergies were modulated only in amplitude by direction. The directional tuning of both types of synergies was well described by a single or a double cosine function. These results suggest that muscle synergies are basic control modules that allow generating the appropriate muscle patterns through simple modulation and combination rules.
Frontiers in Computational Neuroscience | 2013
M. D'Andola; B. Cesqui; A. Portone; Laure Fernandez; Francesco Lacquaniti; Andrea d'Avella
What sources of information and what control strategies the central nervous system (CNS) uses to perform movements that require accurate sensorimotor coordination, such as catching a flying ball, is still debated. Here we analyzed the EMG waveforms recorded from 16 shoulder and elbow muscles in six subjects during catching of balls projected frontally from a distance of 6 m and arriving at two different heights and with three different flight times (550, 650, 750 ms). We found that a large fraction of the variation in the muscle patterns was captured by two time-varying muscle synergies, coordinated recruitment of groups of muscles with specific activation waveforms, modulated in amplitude and shifted in time according to the balls arrival height and flight duration. One synergy was recruited with a short and fixed delay from launch time. Remarkably, a second synergy was recruited at a fixed time before impact, suggesting that it is timed according to an accurate time-to-contact estimation. These results suggest that the control of interceptive movements relies on a combination of reactive and predictive processes through the intermittent recruitment of time-varying muscle synergies. Knowledge of the dynamic effect of gravity and drag on the ball may be then implicitly incorporated in a direct mapping of visual information into a small number of synergy recruitment parameters.
Journal of Motor Behavior | 2014
Hugo Loeches De La Fuente; Laure Fernandez; Jean-Christophe Sarrazin; Eric Berton; Guillaume Rao
ABSTRACT The influences of task difficulty (index difficulty: 2–4), input device of different length, range of motion and mode of resistance (joystick or rotorcraft stick), and directions of movement (leftward rightward) on motor patterns in a realistic control situation were examined with a multilevel analysis (joint kinematics and muscular variables, and global task performance). Eight subjects controlled the displacements of a virtual object during a slalom task characterized by a realistic inertial model. Pilots adapted the endpoint kinematic organization to increasing accuracy constraints to preserve task success whatever the device and the direction. However, the rotorcraft stick manipulation remains highly complex in comparison to the joystick due to poorer proprioceptive information, higher inertial constraints, and an asymmetrical muscle control.
International Geology Review | 2018
Mehdi Mechati; Renaud Caby; Dalila Hammor; Delphine Bosch; Olivier Bruguier; Laure Fernandez
ABSTRACT Metagabbros and amphibolites exposed in the Bou-Maïza area of the Edough massif (northeast Algeria) are described in detail. Field and petro-structural observations point to the syn-sedimentary emplacement of gabbros as clasts, blocks and lenses of polymictic gabbroic breccias. Associated amphibolites display fine-scale parallel sedimentary bedding and represent mafic epiclastites, litharenites and mafic greywackes. The mafic beds and lenses are intercalated with aluminous pelitic schists of continental origin, quartzite and marble. It is concluded that all mafic rocks from this locality derive from the erosion of an oceanic plutono-volcanic complex of MORB affinity that was reworked in a block matrix mélange and emplaced as turbidites and debris flows during the Mesozoic. We propose a convergent plate margin setting for these formations connected with the subducted Calabrian branch of the Tethyan slab.
Experimental Brain Research | 2018
David Gaul; Laure Fernandez; Johann Issartel
The ability to control speed and accuracy of goal directed aiming tasks underpins many activities of daily living. Recent evidence has begun to suggest that obesity can affect the control of movement. This study evaluated perceptual motor control of 183 normal weight, overweight, and obese participants using a discrete Fitts’ task on a digital tablet. In addition, we manipulated tablet orientation to determine whether tablet orientation influences task difficulty with the view to increase the task’s constraints. Our study found that the traditional relationship between target distance and target width hold true for each of the three weight groups in both tablet orientations. Interestingly, no significant differences were found for movement time between the groups, while movement kinematics differed between weight groups. Obese participants demonstrated significantly higher peak acceleration values in the horizontal tablet orientation when compared to their normal weight and overweight counterparts. Further to this, obese participants made significantly more errors than normal weight and overweight groups. These findings suggest that obese individuals have altered control strategies compared to their normal weight peers.
Proceedings of the Royal Society of London B: Biological Sciences | 2010
Raoul Huys; Laure Fernandez; Reinoud J. Bootsma; Viktor K. Jirsa
Tectonophysics | 2014
Delphine Bosch; Dalila Hammor; Mehdi Mechati; Laure Fernandez; Olivier Bruguier; Renaud Caby; Patrick Verdoux
Tectonophysics | 2014
Renaud Caby; Olivier Bruguier; Laure Fernandez; Dalila Hammor; Delphine Bosch; Mehdi Mechati; Rabah Laouar; Aziouz Ouabadi; Nachida Abdallah; Chantal Douchet
Journal of Geodynamics | 2016
Laure Fernandez; Delphine Bosch; Olivier Bruguier; Dalila Hammor; Renaud Caby; Patrick Monié; Nicolas Arnaud; Abder Toubal; Béatrice Galland; Chantal Douchet
Earth and Planetary Science Letters | 2017
Olivier Bruguier; Delphine Bosch; Renaud Caby; Alberto Vitale-Brovarone; Laure Fernandez; Dalila Hammor; Rabah Laouar; Aziouz Ouabadi; Nachida Abdallah; Mehdi Mechati