Right-hemispheric Activation In Chronic Stroke Patients With Aphasia:An Activation Likelihood Estimation(ALE) Meta-analysis

Objective:A large number of neuroimaging and behavioral studies have been conducted on the recombination of language functions in patients with aphasia after stroke.However,the role of the right hemisphere in the recovery of patients has not been agreed when the lesion is located in the left hemisphere.The purpose of this study was to conduct a meta-analysis of whole-brain voxel analysis to explore the role of the right hemisphere in language recovery and its recruitment under different tasks.Subjects and Methods:Studies were selected up to April 2018 from electronic databases including Pub Med,Embase,Corchrane and Web of Science,using a series of keywords to filter,excluded subjects in the literature who did not meet the requirements.Through a series of screens,we identified 22 studies,included 484 activation foci from 269 aphasic patients and 341 foci from 315 control subjects.For the included literature,the information was summarized and the literature data set was summarized.This study used a meta analysis method based on coordinate: activate the likelihood estimation(ALE),using Ginger ALE software to finish.It can quantitatively integrate a large number of functional magnetic resonance imaging(f MRI)studies which have been published.The ALE parameters of all voxels in each brain region were obtained,and then to locate and analyze the brain regions that are continuously and stably activated.This study was divided into three modules: 1)meta-analysis was performed on a single data set of healthy control group and aphasia patients,respectively.To analyze whether the activation pattern of the right hemisphere changes after the injury of the left hemisphere.2)the tasks included in the study were classified into lexical decision and word retrieval task according to the task process described in the literature.To research whether the activation modes of the right hemisphere are different under different tasks,and whether the type of tasks affect the degree of participation of the right hemisphere.3)the contrast analyses method of Ginger ALE software was used to test the significance difference of the analysis results of a single data set under two different tasks,highlighting the voxels with stronger signals under one task than the other,which can also help to identify the activated voxels under both task conditions.Results:1.When a meta-analysis of a single dataset was performed on the control group and the patients,more cerebral regions in the right hemisphere were activated in the patients than in the control group.2.During the lexical decision task,both the control group and the patients only activated part of the brain regions in the left hemisphere,and activated the inferior frontal gyrus,while no activated foci was found in the right hemisphere.3.During the word retrieval task,the patients activated more areas of the right hemisphere than the control group,including the inferior frontal gyrus,insula,precentral and postcentral gyrus,medial frontal gyrus and middle temporal gyrus.4.The contrast analyses results of the control group only showed that the insula and inferior frontal gyrus of the left hemisphere were activated during both tasks,with respect to distinct tasks effects involving activition,no clusters were identified in the contrast analyses.5.The results of the control analysis of aphasia patients showed that the left middle frontal gyrus was activated during the lexical decision task and the word retrieval task.The activation level of the left middle temporal gyrus was significantly higher in the lexical decision task than the word retrieval task.However,word retrieval tasks activated more of the superior temporal gyrus and precentral gyrus in the right hemisphere than lexical decision tasks.Conclusion:1.When the lesion is located in the left hemisphere in aphasia patients with chronic stroke,the involvement of the right hemisphere may be beneficial to the recovery of the patient’s language function.2.Differences in the language tasks performed during f MRI scans resulted in different activation patterns in the right hemisphere between patients and normal controls.The nature of this difference may be based on the cognitive complexity of the task.