Primary motor cortex mapping in brain-lesioned patients using MEG resting-state functional connectivity

• ¹ Université Libre de Bruxelles, Belgium
• ² Aalto University School of Science, Finland
• ³ Ghent University, Belgium

Introduction: The use of resting-state activity for preoperative functional mapping represents a potential alternative to task-related localization in brain-lesioned patients, which requires minimal patients’ collaboration, avoids task-performance confounds and allows investigating several brain systems. This study tested the ability of magnetoencephalography (MEG) resting-state functional connectivity (rsFC) analysis to map the primary motor hand area (M1ha) in a group of presurgical patients. This method is based on the strong resting-state connectivity between the left and right M1ha. Methods: MEG resting-state data were recorded with a whole-scalp MEG (Elekta) in 10 presurgical patients (5 females, mean age: 37.7 years) with focal (6 patients) or hemispheric (3 patients) brain lesions, or refractory neuropathic pain (1 patient) (duration: 373±147s (mean±std), eyes open: 7 patients, eyes closed: 3 patients). MEG data (bandpass: 0.1-45Hz) were corrected for eye-movement and cardiac artifacts using independent component analysis. Source reconstruction was performed using a spherical conductor model determined from patient’s MRI and β-band (12-21 Hz) Minimum Norm Estimation. M1ha seed-based rsFC maps were obtained using slow source Hilbert envelope correlation from a seed located in the non-affected M1ha (MNI coordinates based on functional mapping literature). The localization of the correlation maximum in the hemisphere contralateral to the seed was compared to classical MEG or fMRI functional indicator(s). Results: In all patients, rsFC maps displayed inter-hemispheric resting-state connectivity. In 7 patients, a good concordance between the correlation global maximum located in the hemisphere contralateral to the seed and functional indicator(s) was found (cf. figure 1 for an example). In 1 patient, one local correlation maximum co-localized with functional indicators. Conclusion: This study suggests that MEG resting-state is able to map the M1ha in presurgical patients with brain disorders. Therefore, MEG resting-state might represent an interesting alternative to task-related functional mapping that should be considered as an additional functional indicator in the armamentarium of MEG M1ha mapping methods.