fMRI Study of Speech Processing in Presbycusis Patients / 听力学及言语疾病杂志

ABSTRACT

Objective To study the brain functional activation under speech stimulation in presbycusis pa‐tients using blood oxygenation level dependent functional magnetic resonance imaging (BOLD - fMRI) .Methods Eighteen normal hearing young volunteers ,10 normal hearing elderly people and 10 presbycusis patients received fM ‐RI under auditory task .Experimental tasks included monosyllabic verbal stimulating at tone of 1 kHz and sound in‐tensity to 90 dB ± 3 dB(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 acti‐vated 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 was 12 .06 ,appearing to the right ear advantage (left brain dominance) .While the aged and presbycusis group manifes‐ted as right ear advantage decreased (left ear advantage enhanced) ,whose the total volume ratio was 11 .51 for the old normal subjects and 11 .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 .