Altered Functional Connectivity Of Multiple Resting-state Networks Associated With Motor Dysfunction In Stroke:An Independent Component Analysis

More than half of patients after stroke are left with motor dysfunction,which severely influences the quality and convenience of the patients’ daily life.As its easy operation and powerful ability to analyze spontaneous neural activity,resting-state functional Magnetic Resonance Imaging(resting-state fMRI)has now been an efficient way to investigate the neural mechanism of motor recovery following stroke.Numerous resting-state fMRI studies have suggested that sensorimotor network(SMN)is the the most vulnerable network attacked by motor stroke lesions,but higher-order cognitive control networks,such as frontoparietal network,executive control network and attention network etc.would be changed for the adaption of motor reorganization.However,how these networks react to the motor impairment is still unclear.Independent component analysis(ICA)is a data-driven approach to delineate spatially independent patterns of coherent signals,allowing a direct and fairly straightforward measure of interactions within and between multiple brain networks.So,the focus of this study is to investigate the altered intra-and inter-network functional coupling of resting-state networks associated with motor dysfunction in stroke by using ICA.This study involves two parts.Part I.The purpose of this part was to investigate the abnormal functional connectivityof the sensorimotor network in stroke.Thirty-three left subcortical stroke patients with hemiplegia and thirty-four sex-and age-matched healthy controls were performed resting-state fMRI,which were analyzed by ICAThe sensorimotor network was selected and compared between the two groups by using two sample t-test(P<0.05,AlphaSim corrected).Four SMNs(including the dorsal,ventral,left and right SMN)demonstrated significantly reduced functional connectivity(FC)in stroke patients compared with healthy controls,indicating the widespread impairments of sensorimotor system by stroke.Part II.The purpose of this part was to investigate the changes inintra-and inter-network FCof multiple networksand to further correlate FC with motor performance.ICA were conducted on the same subjects from the research of Part I,and 11 resting-state networks were identified.Both intra-and inter-network FC were compared between the two groups by using two sample t-test(P<0.05,AlphaSim corrected).Compared with healthy controls,the stroke group showed abnormal FC within the SMN,visual network(VN),dorsal attention network(DAN),right frontoparietal network(RFPN)and executive control network(ECN).Additionally,the FC values of the ipsilesional inferior parietal lobule(IPL)within the DAN and ECN were positively and negatively correlated with the Fugl-Meyer Assessment(FMA)scores(hand+wrist),respectively.With respect to the inter-network interactions,DAN decreased FC with the primary perceptual system(including the SMN,motor network and VN)and the default mode network(DMN)increased FC with the RFPN,but the posterior DMN decreased FC with the VN;the FC between the RFPN and ECN disappeared.The results indicated the abnormalities of both intra-and inter-network functional connectivity in multiple resting-state brain networks,and particularly,the disruption of the dorsal attention network and the over-compensation of the executive control network were not good prognostic signs for hand motor recovery in patients with stroke hemiplegia.