Brain oscillatory modes as a proxy of stroke recovery

BackgroundStroke is the leading cause of long-term disability, making the search for successful rehabilitation treatment one of the most important public health issues. A better understanding of the neural mechanisms underlying impairment and recovery, and the development of associated biomarkers is critical for tailoring treatments with the ultimate goal of maximizing therapeutic outcomes. Here, we studied the longitudinal changes in brain oscillatory modes, linked to GABAergic system activity, and determined their importance for residual upper-limb motor functions and recovery. MethodsTranscranial Magnetic Stimulation (TMS) was combined with multichannel Electroencephalography (EEG) to analyze TMS-induced brain oscillations in a cohort of 66 stroke patients from the acute to the late subacute phase after a stroke. ResultsA data-driven parallel factor analysis (PARAFAC) approach to tensor decomposition allowed to detect brain oscillatory modes notably driven by the frequency band, which evolved longitudinally across stroke stages. Notably, the observed modulations of the -mode, which is known to be linked with GABAergic system activity, were associated to the extent of motor recovery. ConclusionsOverall, longitudinal evaluation of brain modes provides novel insights into the functional reorganization of brain networks after a stroke and its underlying mechanisms. Notably, we propose that the observed -mode decrease corresponds to a beneficial disinhibition phase between the early and late subacute stages that fosters structural and functional plasticity and facilitates recovery. Monitoring this phenomenon at the individual patient level will provide critical information for phenotyping patients, developing electrophysiological biomarkers and refining therapies based on personalized excitatory/inhibitory neuromodulation using noninvasive or invasive brain stimulation techniques.