FMRI Study Of Auditory Cortex In Healthy, Sensorineural Hearing Loss And Tinnitus Subjects

PartⅠfMRI study of auditory cortex in healthy subjectsObjective Blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) was used to observe the volume and intensity of the activated auditory cortex evoked by pure tone stimuli in healthy subjects,to analyze the volume and intensity of the two hemispheres of the activated auditory cortex quantitatively,and to compare the difference of the auditory cortex between left and right hemispheres.Materials and methods 15 healthy subjects underwent BOLD-fMRI examination.The block design was used,the sound of 1000 Hz and 90 dB pure tone was used as stimulating signal.Stimulating phase and resting phase were ordered alternately.The gradient echo planar imaging(GRE-EPI) was used to rapidly acquire whole brain imaging.SPM2 software was used to deal with the original pictures in the off-line work station,to get maps,volume and intensity of the activated auditory cortex in left and right hemispheres.Results Significant activation was found in temporal lobe in all the healthy subjects,and it was also found in frontal lobe,precentral gyrus,occipital lobe and parietal lobe etc in some of them.When unilateral ear got signal, there was significant difference between contralateral and ipsilateral activated auditory cortex of all the 15 healthy subjects(P＜0.01).Conclusions 1.The volume and intensity of activated cortex can be quantified precisely by SPM2.2.When one ear got stimulated by pure tone,both auditory cortexes show actived,the volume and intensity of the contralateral activated auditory cortex is greater than that of the ipsilateral auditory cortex,contralateral predominance is quite clear.PartⅡfMRI study of auditory cortex in sensorineural hearing loss patientsObjective BOLD-fMRI was used to observe the volume and intensity of the activated auditory cortex evoked by pure tone stimuli in sensorineural hearing loss patients,to analyze the volume and intensity of the two hemispheres of the activated auditory cortex quantitatively,and to compare the difference of the auditory cortex between left and right hemispheres.According to syndrome differentiation typing(SDT) of Traditional Chinese Medicine(TCM),the volume and intensity of the activated auditory cortex was analyzed. Finally,the characteristic of the auditory cortex of sensorineural hearing loss patients was discussed.Materials and methods 22 unilateral moderate-severe sensorneural hearing loss patients underwent BOLD-fMRI examination.12 of them were ill in their left ears,and 10 of them were ill in their right ears.The block design was used,the sound of 1000 Hz and 90 dB pure tone was used as stimulating signal.Stimulating phase and resting phase were ordered alternately.The GRE-EPI was used to rapidly acquire whole brain imaging.SPM2 software was used to deal with the original pictures in the off-line work station,to get maps, volume and intensity of the activated auditory cortex in left and right hemispheres.Results When the abnormal ear got signal,significant activation in temporal lobe was found in only 10 of the 22 patients.However,when the normal ear got signal,significant activation was found in 19 of them.Some of them also showed significant activations in frontal lobe, precentral gyrus,occipital lobe,parietal lobe etc.When the normal ear got signal,there was no significant difference between contralateral and ipsilateralt activated auditory cortex (P＞0.05).Conclusions 1.When the normal ear of sensorneural hearing loss patients were stimulated by pure tone,the contralateral hemisphere predominance disappeared.The result seems to show a plasticity of auditory cortex of monaural deaf patient.2.According to SDT of TCM,there was no obvious difference between TCM excessive syndrome and deficiency-syndrome on the volume and intensity of the activated auditory cortex.PartⅢfMRI study of auditory cortex in tinnitus patientsObjective BOLD-fMRI was used to observe the volume and intensity of the activated auditory cortex evoked by pure tone stimuli in chronic tinnitus patients,to analyze the volume and signal intensity of the two hemispheres of the activated auditory cortex quantitatively,and to study the characteristic of the auditory cortex of chronic tinnitus patients.Materials and methods 7 chronic tinnitus patients underwent BOLD-fMRI examination.The block design was used,the sound of 1000 Hz and 90 dB pure tone was used as stimulating signal. Stimulating phase and resting phase were ordered alternately.The GRE-EPI was used to rapidly acquire whole brain imaging.SPM2 software was used to deal with the original pictures in the off-line work station,to get maps,volume and signal strength of the activated auditory cortex in left and right hemispheres.Results Significant activations were found in temporal lobe,frontal lobe,precentral gyrus,occipital lobe,parietal lobe etc of chronic tinnitus patients.However,there was no obviously regularity on the volume and intensity of the activated auditory cortex.Conclusions Chronic tinnitus patients may exist the abnormal neural activity in auditory cortex.