老年性聋患者言语半球优势的功能磁共振成像研究

fMRI Study of Speech Processing in Presbycusis Patients

目的应用血氧水平依赖功能磁共振成像(blood oxygenation level dependent-functional magnetic resonance imaging,BOLD-fMRI)研究老年性聋患者言语声刺激下听觉皮层激活的半球优势及耳别优势的变化。方法选取18例健康青年志愿者(青年组)、10例正常听力老年人(老年组)及10例老年性聋患者(老年性聋组)为研究对象,分别进行单音节言语任务下的fMRI检测,刺激声频率为1kHz,声强90±3dB SPL,进行大脑激活偏侧性分析,以偏侧化指数(laterality inelex,LI)表示,LI≥0.20为左侧大脑半球优势,LI≤-0.20为右侧大脑半球优势,-0.20≤LI≤0.20为双侧大脑半球优势;观察老年性聋患者半球优势变化(或耳别优势变化)。结果青年组左、右耳分别刺激时,偏侧化指数分别为-0.58、0.37;老年组左、右耳分别刺激时,偏侧化指数分别为-0.24、0.28,老年性聋组左、右耳刺激时,偏侧化指数分别为-0.18、0.25。左、右耳行听觉任务时,青年组耳别优势为1:2.06,表现为右耳(左脑)优势;老年组为1:1.51,老年性聋组为1:1.61,右耳优势减弱。结论青年人单耳刺激大脑皮层的激活存在明显的偏侧性,表现为对侧半球传导优势,并以左耳的对侧化传导更明显,衰老与耳聋后听皮层存在功能重组,出现对侧半球传导优势减弱的趋势。青年人行听觉任务时表现为右耳(左脑)优势,衰老后右耳优势减弱(左耳劣势增强),而这种变化可能是老年人言语识别能力下降的原因之一。

Objective To study the brain functional activation under speech stimulation in presbycusis patients using blood oxygenation level dependent functional magnetic resonance imaging（BOLD-fMRI）.MethodsEighteen normal hearing young volunteers,10 normal hearing elderly people and 10 presbycusis patients received fMRI under auditory task.Experimental tasks included monosyllabic verbal stimulating at tone of 1kHz and sound intensity to 90 dB ± 3dB（after ambient noise detector Smart Sensor AR844 measurement and calibration）randomly transmitted to left and right ear.Following block design,each stimulus was repeated twice.The lateralization of brain activation analysis observed changes in hemispheric dominance cases（or ear advantage change）.We observed brain activation analysis and changes of hemispheric lateralization advantage（or ear advantages）.SPM5 software was used to deal with the original pictures in the off-line work station to get fictional maps,volume and intensity of the activated brain regions of interest,and calculate the laterality index（LI）.Results To young people,regardless of left or right ear stimulation,the contralateral（region of intrest,ROI）activation volume and intensity significantly increased compared to ipsilateral,appearing contralateral hemispheric dominance,and laterality index were-0.58（left ear stimulation）and 0.37（right ear stimulation）.Compared to young people,elderly people with normal hearing and presbycusis contralateral hemisphere conduction advantage was significantly reduced under monaural stimulation,and the laterality indexes were-0.24,0.28（the aged group）,-0.18,0.25（presbycusis group）.Young people received the left and the right ear auditory task respectively,and the ratio of the total volume of bilateral ROI activation was1：2.06,appearing to the right ear advantage（left brain dominance）.While the aged and presbycusis group manifested as right ear advantage decreased（left ear advantage enhanced）,whose the total volume ratio was 1：1.51 for the old normal subjects and 1：1.61 for the hearing impaired seniors.Conclusion Auditory verbal tasks activated brain regions in the superior temporal gyrus and middle temporal gyrus were most obvious.Aging may cause these brain regions to be activated weaker,appearing to the trend of contralateral hemisphere.The aging and deafness lead to the cortical reorganization.This may be one of the reasons for the declined speech recognition.