Neural bases of independent and coordinated hand movements

Individuation and coordination of finger and hand movements represent crucial processes in motor control. The present work intended to characterize the role of the main neural structures thought to be involved in these particular motor functions. In the first chapter, we have demonstrated that, in humans, the corticospinal (CS) tract is the major neural pathway responsible for the control of fine finger movements. In particular, we found that the impaired finger dexterity in the paretic hand of congenital hemiplegic (CH) patients was strongly correlated with the extent of their CS dysgenesis, as estimated by measuring the surface of the cerebral peduncles (Duque et al., 2003). In a second study, by using the grip-lift task, we also demonstrated the importance of cutaneous feedback for dextrous object manipulation (Duque et al., 2005a). In the second chapter, we performed several studies that aimed at characterizing the role of inhibitory interhemispheric interactions (IHI) in the control of unilateral hand movements. We have found that modulation of IHI was much more pronounced for right than left hand movements in right handed individuals. This modulation essentially consisted of a shift from a balanced IHI between the two hemispheres, at rest, to an IHI predominantly directed towards the ipsilateral motor cortex (M1) at movement onset (Duque et al., 2005b). Such a mechanism might release muscle representations from inhibition in the contralateral M1 while preventing the occurrence of mirror activity in the ipsilateral M1. It could therefore provide an important benefit for the control of dominant hand movements. Interhemispheric inhibition was found abnormally modulated in stroke patients moving their paretic hand, a phenomenon that could contribute to reinforce their impaired digital dexterity (Murase et al., 2004; Duque et al., 2005c). Performance of complex bimanual movements is thought to rely on the integration of a common goal linking the action of both hands, or what is called intermanual coordination. The last chapter aimed at identifying neural structures ensuring intermanual coordination during continuous bimanual hand movements. To do so, we used functional magnetic resonance imaging to compare brain activation while subjects performed continuous bimanual circling movements requiring either independence or coordination. We evidenced differential cortical regions involved in these two tasks; The M1, the supplementary motor area, and the superior temporal gyrus in the right hemisphere were substantially more activated in bimanual coordination as compared to bimanual independence. In addition, we found that a higher activation in the bilateral middle cingulate regions and precuneus as well as in the right premotor cortex in the coordination than independent task was highly correlated with the quality of spatiotemporal control in bimanual coordination. These regions are therefore likely to play a crucial role in the control of the common action goal underlying performance of complex coordinated actions. In conclusion, our study evidences a predominant role of the right hemisphere and medial wall regions in bimanual coordination.Thèse de doctorat en sciences biomédicales (neurosciences)(SBIM 3) -- UCL, 200

Role of Broca’s area in motor sequence programming

International audienceBesides language, the contribution of Broca’s area to motor cognition is now widely accepted. In this study, we investigated the role of its posterior part (left Brodmann area 44) in learning of a motor sequence by altering its functioning with a continuous theta-burst transcranial magnetic stimulation (cTBS) in 12 healthy participants before they learned the sequence by observation. Twelve control individuals underwent the same experiment with cTBS applied over the vertex. Although cTBS over Brodmann area 44 did not impair sequence learning, it significantly increased the response latency as measured during the retention test, performed 24 h later. This finding suggests that Broca's area might be critically involved in organizing, and/or storing, the individual components of a motor sequence before its execution

Expérimentation animale: la recette d'une polémique scientifique

La majorité du grand public accepte l’expérimentation animale à condition que celle-ci contribue à l’amélioration de la santé humaine et qu’aucune autre alternative n’existe. En face, les opposants décrédibilisent la recherche et stigmatise une profession à des fins idéologiques. Relevé de leurs arguments

The coming decade of digital brain research - A vision for neuroscience at the intersection of technology and computing

Brain research has in recent years indisputably entered a new epoch, driven by substantial methodological advances and digitally enabled data integration and modeling at multiple scales – from molecules to the whole system. Major advances are emerging at the intersection of neuroscience with technology and computing. This new science of the brain integrates high-quality basic research, systematic data integration across multiple scales, a new culture of large-scale collaboration and translation into applications. A systematic approach, as pioneered in Europe’s Human Brain Project (HBP), will be essential in meeting the pressing medical and technological challenges of the coming decade. The aims of this paper are To develop a concept for the coming decade of digital brain research To discuss it with the research community at large, with the aim of identifying points of convergence and common goals To provide a scientific framework for current and future development of EBRAINS To inform and engage stakeholders, funding organizations and research institutions regarding future digital brain research To identify and address key ethical and societal issues While we do not claim that there is a ‘one size fits all’ approach to addressing these aspects, we are convinced that discussions around the theme of digital brain research will help drive progress in the broader field of neuroscience. Comments on this manuscript are welcome This manuscript is a living document that is being further developed in a participatory process. The work has been initiated by the Science and Infrastructure Board of the Human Brain Project (HBP). Now, the entire research community is invited to contribute to shaping the vision by submitting comments. Comments can be submitted via an online commentary form here. All submitted comments will be considered and discussed. The final decision on whether edits or additions will be made to the next version of the manuscript based on an individual comment will be made by the Science and Infrastructure Board (SIB) of the Human Brain Project (HBP) at regular intervals. New versions of the manuscript will be published every few months on Zenodo. Comments may be submitted until the beginning of 2023. During the Human Brain Project Summit 2023, the manuscript will be adopted by HBP and non-HBP participants, and a final version will be published shortly after

L’expérimentation animale reste indispensable (OPINION)

Trop fréquemment, l’expérimentation animale est présentée comme une pratique archaïque. Elle a bien changé. Et 100 % des patients traités le sont grâce aux concepts et techniques développés grâce à elle