Early motor network connectivity after stroke: An interplay of general reorganization and state‐specific compensation. Issue 16 (4th August 2021)

• Record Type: Journal Article
• Authors: Paul, Theresa; Hensel, Lukas; Rehme, Anne K.; Tscherpel, Caroline; Eickhoff, Simon B.; Fink, Gereon R.; Grefkes, Christian; Volz, Lukas J.
• Is Part Of: Human brain mapping. Volume 42:Issue 16(2021)
• Page Start: 5230
• Page End: 5243
• Publication Date: 2021-08-04
• Subjects: brain network connectivity -- dynamic causal modeling (DCM) -- ischemic stroke -- motor network reorganization -- resting‐state fMRI; Brain mapping -- Periodicals; 611.81
• DOI: 10.1002/hbm.25612
• Languages: English
• ISSNs: 1065-9471

Abstract

Abstract: Motor recovery after stroke relies on functional reorganization of the motor network, which is commonly assessed via functional magnetic resonance imaging (fMRI)‐based resting‐state functional connectivity (rsFC) or task‐related effective connectivity (trEC) . Measures of either connectivity mode have been shown to successfully explain motor impairment post‐stroke, posing the question whether motor impairment is more closely reflected by rsFC or trEC. Moreover, highly similar changes in ipsilesional and interhemispheric motor network connectivity have been reported for both rsFC and trEC after stroke, suggesting that altered rsFC and trEC may capture similar aspects of information integration in the motor network reflecting principle, state‐independent mechanisms of network reorganization rather than state‐specific compensation strategies. To address this question, we conducted the first direct comparison of rsFC and trEC in a sample of early subacute stroke patients ( n = 26, included on average 7.3 days post‐stroke). We found that both rsFC and trEC explained motor impairment across patients, stressing the clinical potential of fMRI‐based connectivity. Importantly, intrahemispheric connectivity between ipsilesional M1 and premotor areas depended on the activation state, whereas interhemispheric connectivity between homologs was state‐independent. From a mechanistic perspective, our results may thus arise from two distinct aspects of motor network plasticity: task‐specific compensation within the ipsilesional hemisphere and a more fundamental form of reorganization between hemispheres. Abstract : Resting‐state functional connectivity (rsFC) and task‐related effective connectivity (trEC) assessed via functional magnetic resonance imaging readily explain variance in motor performance in early subacute stroke patients. However, directly comparing both approaches, our findings suggest that rsFC and trEC may reflect distinct aspects of motor network plasticity: task‐specific compensation within the ipsilesional hemisphere and a more fundamental form of reorganization between hemispheres.