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Applications en neurosciences fondamentale et clinique des cartographies robotisées de stimulation corticale

on the April 1, 2021
2p.m. in english

Doctoral thesis defense of Brice PASSERA

Thursday 1st April at 2 p.m., Brice PASSERA will defend his thesis called "Applications en neurosciences fondamentale et clinique des cartographies robotisées de stimulation corticale".

This thesis was supervised by Olivier DAVID, Alan CHAUVIN (LPNC) and Sylvain HARQUEL (LPNC).

Abstract :

Transcranial magnetic stimulation (TMS) is a powerful tool to probe the human brain. Thanks to increasing technological and methodological development, the technique is now widely used in clinical and fundamental research, such as a measurement of drugs’ efficiency, a biomarker for different pathologies or a treatment for neurologic and psychiatric diseases. Robotization of the TMS coil opened new possibilities for cortical stimulation mapping protocols in clinical and functional neuroimaging. The aim of this thesis is to study both fundamental and clinical applications of robotized TMS mapping as the latest technological advance to date. In the first axis, we explored methodological development of the coupling of TMS and electroencephalography (EEG). In the second axis, we tested these developments as diagnostic and treatment tools in two pathological contexts. The first axis is composed of two studies aiming at using robotized mapping to better define two key parameters of TMS-EEG coupling. First, we assessed the influence of stimulation intensity on the evoked response of three different cortical targets. To do so, we introduced new analytics, the Regression Quality Score, to derive region-specific input-output curves redefining cortical excitability in non-motor areas. Such results are of particular interest in the context of stimulation individualization across cortical targets and subjects. The second study aims at exploring the spatial resolution of TMS-EEG, by comparing the evoked dynamics of 9 neighboring targets over the sensorimotor cortex. We showed that the spatial resolution of TMS-EEG might be at least as low as 10 mm, while some overlap between the evoked dynamics can yet be found between neighboring sites, especially when the latter share common cytoarchitectonics. Overall, these findings suggest that TMS-EEG is an accurate technique for mesoscale brain mapping and provide new insights about its spatial resolution to be considered for future clinical applications. The second axis of this manuscript was to develop robotized TMS mapping in clinical settings. First, we performed a high-resolution mapping of the visual areas in a patient suffering from continuous visual hallucinations following the resection of a tumor. We found a deafferented area in her right visual hemisphere involved in the hallucinations. With a single rTMS session, we managed to temporary reduce the intensity of her hallucinations. In a second study, we used robotized mapping to explore the effects of Deep Brain Stimulation (DBS) on the motor control network in Parkinsonian patients. Preliminary results tend to show that DBS re-established motor inhibitory processes in the cortex and lowered the cortical hyper-excitability induced by the disease. Overall, these results show that robotized mapping can be a powerful tool in multiple contexts. The ability to perform thorough explorations of the cortex provided by this technique can be used both to further the knowledge about cortical stimulation itself and expand its use in clinical and cognitive neurosciences.

Jury :

  • Mireille Bonnard, Institut de Neurosciences des systèmes, Marseille, Rapportrice
  • Marcello Massimini, Université de Milan, Rapporteur
  • Renaud JARDRI, Université de Lille, Examinateur
  • Pascal HOT, Université Savoie Mont Blanc, Chambéry, Examinateur
  • Valérie FRAIX, CHU Grenoble Alpes, Grenoble, Invitée
  • Olivier DAVID, Grenoble Institut des Neurosciences, Grenoble, Directeur de thèse
  • Alan CHAUVIN, Laboratoire de Psychologie et NeuroCognition, Grenoble, Co-encadrant
  • Sylvain HARQUEL, Laboratoire de Psychologie et NeuroCognition, Grenoble, Co-encadrant

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Updated on March 26, 2021

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