Recherche translationnelle en santé,
technologie pour la santé et recherche clinique
Axis 3 : Neurobiomechanics / Topic 1
Spinal and supraspinal nervous mechanisms involved in the muscle activity control.
This research axis aims to study the spinal and supra-spinal nervous mechanisms of the control of agonist and antagonist muscle activity in healthy participants, expert athletes and patients with motor disabilities.
A first objective is to contribute to a better understanding of the functional role of cortico-cortical, cortico-muscular and intermuscular couplings in the regulation of muscular activity, in relation to motor performance. A second objective is to explore the contribution of spinal and supra-spinal mechanisms to the control of voluntary muscle contraction and to the modulation of these interactions.
This work is based on the study of electroencephalographic and electromyographic signals during isometric and anisometric contractions as well as during more ecological movements. They are based on an interdisciplinary approach with the aim of contributing to the development of a model of control of muscle activity in terms of dynamic coupling between the central, spinal and peripheral levels during motor performance. Beyond their fundamental aspects, these projects are inseparable from our clinical research work on brain injured patients, in order to highlight significant translational implications in a perspective of therapeutic innovation facilitating the recovery of motor function, in particular concerning elbow extension deficit in post-stroke patients with loss of motor function of the upper limb.
Currents projects
Corticospinal adaptations induced by eccentric muscle strengthening – principal investigator: Julien DUCLAY.
The ACRE project aims to better understand the adaptations induced by muscle strengthening conducted over several weeks on corticomuscular coherence (CMC). CMC, a marker of mutual interactions between electrophysiological activities of the motor cortex and muscle, is a promising measurement tool in the study of motor control. However, despite an increasing use of this non-invasive marker over the last decades, the contribution of nervous mechanisms involved in its regulation and in particular at the spinal level, remains to date to be clearly defined. The objective of the ACRE project is to study the effects induced by muscle training on CMC and to determine the involvement of spinal nervous mechanisms in these changes in cortico-muscular interactions. The ACRE project will deepen our knowledge of the mechanisms underlying the regulation of CMC, a marker with multiple applications, particularly in the assessment of motor control. This project therefore presents a dual perspective, both fundamental and applied. In order to meet these goals, ACRE will combine analyzes of the participant’s mechanical response with electrophysiological signals recorded by electromyography (EMG) and electroencephalography (EEG).
Cortico-muscular coherence in anisometric voluntary contractions – Doctoral student : Dorian GLORIES, Director : Julien DUCLAY.
The capabilities of an individual’s neuromuscular system can be measured by determining the moment of force produced at a joint during a contraction. This performance depends on mechanical and neurophysiological factors.
From a neurophysiological point of view, the specific modulation of corticospinal excitability occurring during eccentric-type contractions is believed to depend mainly on pre- and postsynaptic inhibition mechanisms acting at the spinal level.
The analysis of the spectral relationship between the oscillatory electrophysiological activities of the primary motor cortex and the muscle involved in motor performance, recorded by electroencephalogram and electromyogram respectively, is called cortico-muscular coherence (CMC). Although its underlying neurophysiological mechanisms are still debated, CMC represents an analytical tool suitable for the characterization of corticospinal regulations of muscle activity.
Of all the factors that modulate CMC, strength level has been one of the most studied. However, to our knowledge, no study has measured the effects of contraction intensity on CMC during anisometric contractions. The use of anisometric contractions would then allow a better understanding of the cortical and spinal mechanisms of CMC regulation.
The aim of this thesis will therefore be to compare the evolution of CMC between voluntary isometric, concentric and eccentric contractions, for different contraction intensities. We expect to observe i) a reduction in the amplitude of CMC specific to eccentric contractions, related to the increase in recurrent inhibition, and ii) a decrease in CMC with increasing level of activity generated regardless of the contraction mode.
Central mechanisms of healthy and impaired motricity : functional role of cortico-muscular coupling dynamic – PhD student : Maxime FAUVET, Director : David AMARANTINI, Co-director : David GASQ.
This project, located at the crossroads of biomechanics, neurosciences and signal processing, aims to contribute to a better understanding of motor control. Through consistency analysis between EMG and EEG recordings, it is possible to determine the relative involvement of the different movement control mechanisms. The dynamic study of coherences (corticomuscular, corticocortical and intermuscular) over time has never been carried out but can provide information on the temporal organization of the various couplings at the origin of the control of motor activity. This work consists of an analysis of data (EEG and EMG) already collected by the team in healthy subjects, expert subjects and tetraplegic patients and a recording of new data in post-stroke patients as well as their treatment. The final goal of this project is the development of a dynamic model of motor activity control as well as improved management of patients with impaired motor skills.
Contribution of intermuscular coherence as data reflecting nerve strategies for estimating muscle forces – PhD student: Emilie MATHIEU, Director : Philippe PUDLO, Co-director : David AMARANTINI.
The estimation of the muscular forces developed by each muscle involved in a motor action is of great clinical interest. Due to the problem of musculoskeletal redundancy, it is not easy to reliably determine the contribution of each muscle at the resulting moment. Biomechanical models make it possible to determine the resulting moments of force produced at the joints from these data. It is then necessary to formulate hypotheses and use the redundancy of the input data in order to obtain an estimate of the contribution of each physiologically realistic muscle. However, these models do not take into account the nerve strategies implemented for the coordination of muscle activations. This research project focuses on the one hand on determining the link between intermuscular coherence and the control of synergistic muscles, i.e. participating in the same motor action and on the other hand on improving an existing biomechanical model by taking into account of synergistic muscle control strategies in order to increase the reliability of the results obtained.
