| Objective:Swallowing is a complex reflex activity,in which any damage may lead to dysphagia,leading to eating difficulties,aspiration and other complications,which will not only have a serious impact on the quality of life and living standards of patients,but also cause a great social burden.At present,acid stimulation is often used to treat dysphagia,especially post-stroke dysphagia,and it has become a routine and effective treatment.However,the mechanism of pivot action is still unclear.This study attempts to use task-state functional magnetic resonance imaging(functional magnetic resonance imaging,fMRI)to study the distribution of brain functional activation areas related to volitional swallowing in healthy adults,to analyze the similarities and differences of brain functional activation during empty swallowing(swallowing saliva),water swallowing(swallowing room temperature distilled water)and acetic acid swallowing(swallowing acetic acid solution),and to study the effect of acid stimulation on swallowing center,and provide biological basis for the central therapeutic mechanism of acid stimulation.Methods:Thirteen right-handed healthy adults recruited in the community from May 2022 to February 2023 were selected for three different task-state fMRI tests,namely empty swallowing,water swallowing and acetic acid swallowing.The task state experiments were designed with block-design:resting block 30 s + task(empty swallowing,water swallowing and acetic acid swallowing)block 30 s,repeated 6 times.The subjects kept still in the rest block and swallowed every 6s in the task block.At the same time,fMRI scanning was performed to obtain functional image data.The image data were preprocessed by RESTplus software,and the three swallowing tasks were modeled by general linear model and the activation intensity and volume were generated by spm12 software.Finally,the activation intensity and volume of acetic acid swallowing-empty swallowing and acetic acid swallowing-water swallowing were tested by SPSS software to compare the similarities and differences of brain functional activation among healthy subjects during three swallowing tasks.Results:(1)In the empty swallowing task,the brain functional activation areas of healthy adults were mainly located in bilateral cerebellum,bilateral auxiliary motor area,bilateral cingulate gyrus,bilateral superior temporal gyrus,bilateral peritalar fissure cortex,bilateral insular lobe,bilateral superior marginal gyrus,right triangular inferior frontal gyrus,left inferior insular gyrus,bilateral precentral gyrus,postcentral gyrus and bilateral lingual gyrus(corrected by cluster level FDR multiple comparisons,voxel level p<0.001,cluster level p<0.05).(2)During the water swallowing task,the brain functional activation areas of healthy adults were mainly located in bilateral cerebellum,bilateral cingulate gyrus,bilateral superior temporal gyrus,bilateral peri-taloid cortex,bilateral insular lobe,right lenticular nucleus,bilateral superior marginal gyrus,right triangular inferior frontal gyrus,bilateral inferior frontal gyrus,bilateral precentral gyrus,bilateral postcentral gyrus,bilateral cuneate gyrus,bilateral lingual gyrus,bilateral fusiform gyrus,right middle frontal gyrus,right parahippocampal gyrus.Bilateral middle temporal gyrus and bilateral thalamus(corrected by cluster level FDR multiple comparisons,voxel level p<0.001,cluster level p<0.05).(3)During the acetic acid swallowing task,the brain functional activation areas of healthy adults were mainly located in bilateral cerebellum,bilateral auxiliary motor area,bilateral cingulate gyrus,bilateral superior temporal gyrus,bilateral peri-taloid cortex,bilateral insular lobe,right lenticular nucleus,bilateral superior marginal gyrus,bilateral triangular inferior frontal gyrus,bilateral inferior frontal gyrus,bilateral precentral gyrus,postcentral gyrus,left cuneate gyrus,bilateral lingual gyrus,bilateral fusiform gyrus,right middle frontal gyrus.Bilateral middle temporal gyrus,bilateral thalamus,right caudate nucleus(corrected by cluster level FDR multiple comparisons,voxel level p<0.001,cluster level p<0.05).(4)Based on the peak coordinate points of 13 clusters activated during acetic acid swallowing task,the brain functional activation intensity of acetic acid swallowingempty swallowing and acetic acid swallowing-water swallowing tasks were compared.It was found that the activation intensity of the third and ninth activated clusters of healthy adults during acetic acid swallowing task was stronger than that of empty swallowing task,and the difference was statistically significant.The peak coordinates were located in the right postcentral gyrus(t=2.57,p=0.042)and the left cerebellum Ⅷ lobule(t=2.46,p=0.049),respectively.And compared with the water swallowing task,the activation intensity of the second and seventh activated clusters of healthy adults during the acetic acid swallowing task was stronger,and the difference was statistically significant.The peak coordinates were located in the left triangular inferior frontal gyrus(t=2.91,p=0.027)and the right triangular inferior frontal gyrus(t=3.47,p=0.013),respectively.(5)The brain functional activation volumes of the left and right hemispheres of all subjects under three swallowing tasks were calculated,and there was no statistical difference between acetic acid swallowing-empty swallowing and acetic acid swallowing-water swallowing(p value range 0.30-0.46).Conclusion:In this study,task state fMRI technique was used to detect the similarities and differences of brain functional activation between acetic acid swallowing stimulation,empty swallowing and water swallowing in healthy adults.It was found that during acetic acid swallowing task,the activation intensity of right postcentral gyrus and left cerebellar Ⅷ lobule was stronger than that of empty swallowing task,and the activation intensity of bilateral triangular inferior frontal gyrus was stronger than that of water swallowing task,suggesting that acid stimulation can affect brain functional activity of healthy adults during swallowing task.The effect of acid stimulation may be related to the regulation of functional activities of swallowing-related centers. |
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