The Functional Connectivity Study Of Mirror Neuron System And Swallowing Network

Background and Objective Mirror neurons system(MNs)contains a set of neurons capable of firing during action observation and execution.Action observation(AO)as a novel tool for functional recovery during stroke rehabilitation,aiming to excite the MNs when patients observe a goal-directed motor action,and to mobilize the common brain area of MNs and the directed action,and to activate the functional recovery of damaged brain areas from the top down.Dysphagia after stroke can result in serious complications and is strongly linked to a deteriorated quality of life.Regrettably,the outcome of clinical treatment is typically poor.Therefore,repairing the damaged networks directly to improve swallowing function has become a challenge demanding a prompt answer.Previous studies have found that some brain areas of swallowing regulation overlap those with MNs.As yet,there is paucity of reliable evidence demonstrating that the functional connectivity of MNs and swallowing network,prompting us to conduct the current experiment.We employed task-based functional magnetic resonance imaging(f MRI)in healthy volunteers as the research subjects to identify the connectivity of MNs and swallowing network,from the several aspects,such as the common neural nodes,functional connectivity,and effective connectivity,and to provide theoretical foundation for application of AO in the treatment of dysphagia.Methods1? We scanned twenty-nine healthy volunteers by task-based f MRI,and analyzed the brain activation in each task to compare the activation of MNS and swallowing network during the observation and execution of swallowing,and to find the common neural nodes between the two processes.2? We collected the f MRI data of fifty-two healthy volunteers,and adopted independent component analysis(ICA)to separate networks,and then to explore the functional network connectivity(FNC)between the MNs and swallowing network.3? Based on the results of FNC,we extracted the time series information of the region of interest(ROI)from the f MRI data of fifty volunteers,and two volunteers in all fifty-two were excluded due to insufficient ROI.Finally,we use dynamic causal modeling(DCM)to construct the optimal effective connectivity model between MNS and swallow network.Results1? Many brain regions were activated during observation of swallowing,including the middle temporal gyrus,inferior frontal gyrus,pre-and postcentral gyrus,supplementary motor area,hippocampus,brainstem,and pons.Execution of swallowing resulted in activation of motor areas as well as other brain areas,including the inferior parietal lobule,vermis,middle frontal gyrus,and middle temporal gyrus.Two brain areas,BA6 and BA21,were activated with both observation and execution of swallowing.2? ICA separately showed six networks related to observation of swallowing and eight networks in connection with execution of swallowing.The analysis of FNC indicated the functional network connectivity was complex between observation and execution of swallowing.The basal ganglia network and salience network were highly correlated with the both tasks.In addition,the connectivity of dorsal attention network and sensorimotor was the strongest in all.3? At baseline,the left occipital lobe had strong self-inhibition and inhibited the thalamus and precentral gyrus,and the other ROIs bonded and excited with each other.During the observation of swallowing,our results showed that all the self-connections had negative value;the left insula,precentral gyrus,occipital lobe and thalamus showed directional inhibition,and the right SMA also had negative effect to the left occipital lobe.During the execution of swallowing,only ROIs in the left hemisphere had effective connectivity;the self-inhibition of occipital lobe was weakened,and the connections from the caudate were excitatory on the thalamus,but the frontal lobe had positive influence on the insula.Conclusion1? BA6 and BA21 can be activated in both observation and execution of swallowing,and they are common neural nodes of MNs and swallowing network.2? The dorsal attention network,basal ganglia network,salience network and sensorimotor network may play crucial roles in the functional network connectivity of MNS and swallowing network.3? Observation and execution of swallowing must occur simultaneously to activate the effective connectivity of MNS and swallowing network.