| Objective: To observe responses evoked by pure tones in healthy and sensorineural hearing loss subjects with MEG. To compare the differences of the AEFs in left and right hemisphere. To compare the differences of the AEFs in healthy subjects at variable SPL. To compare the differences of the AEFs in sensorineural hearing loss subjects at variable SPL. To compare the differences of the AEFs evoked by pure tones in healthy and that in sensorineural hearing loss subjects with MEG.Materials and Methods: There were two groups in this study, which included 10 healthy medical student subjects and 10 sensorineural hearing loss middle school student subjects. Every healthy subject received stimuli of 1kHz tone bursts delivered to the bilateral ear at duration 8ms, ISI Is and SPL 30dB and 90dB; The SPL of tone bursts that every hearing loss subjects received were sub-, iso- and super- to each one's hearing threshold. All subjects examined with 306-channel whole-scalp neuromagnetometer of 4D-Neuroimaging and 1.5T MRI scanner of GE, and the data was processed with MEG-MRI Integration software. Results: In 10 normal-hearing controls the most evident AEFs evoked with pure tone was Ml00, which When superimposed on MRI located precisely on the Heschl's gyrus. Source strength of Ml00 in right hemisphere was stronger compared with that in left hemisphere, and the Ml00 of right hemisphere had shorter latencies than that in left hemisphere. When the AEFs evoked with 30dB and 90dB pure tones were compared, we found that the Ml00 of 90dB had shorter latencies and stronger strength than that of 30dB. But there was no significantly different from the location of Ml 00 ECD in 30dB and 90dB tones. In 10 sensorineural hearing loss subjects no AEFs evoked with pure tone atintergroups analysis was performed successively.Results: For healthy subjects to pure tone stimuli, significant activations wereobserved in bilateral Heschl's gyri, anterior pole of planum temporale, planumtemporale, precentral gyri, postcentral gyri, supramarginal gyri, superior temporalgyri, inferior frontal gyri, occipital lobes and cerebellums. The results of statisticalanalysis of the two hemisphere' data demonstrated that there was obvious increasein extent and magnitude of activation in functional areas in right hemisphere thanthat in left hemisphere, which included: Heschl's gyri, anterior pole of planumtemporale, planum temporale, postcentral gyri, superior temporal gyri andcerebellar hemisphere. But precentral gyri and supramarginal gyri showed moreobvious activation in left hemisphere than in right, and no obvious difference wasfound between bilateral inferior frontal gyri, occipital lobes. Compared withhearing loss subjects, healthy subjects showed more extensive and intensiveactivation in bilateral Heschl's gyri, anterior pole of planum temporale, inferiorfrontal gyri, left superior temporal gyri and right planum temporale. But inprecentral gyri, postcentral gyri and occipital lobes the activation is moreintensive in hearing loss subjects than that in healthy subjects.Conclusion: Under a proper pure tone stimulus the activation of auditory cortexcan be elicited both in healthy and sensorineural hearing loss subjects on BOLD-fMRI. For healthy subjects the activation of auditory cortex elicited by pure tonestimulus showed a rightward predominance. In healthy subjects, the auditoryresponse was more extensive and intensive than that in hearing loss subjects.Obvious activation was elicited in bilateral occipital lobes both in healthy and insensorineural hearing loss subjects, which indicated there was an intrinsic relationbetween the auditory and visual cortex. There were cortex reorganizations in thesensorineural hearing loss subjects.Objective: To observe responses evoked by pure tones in healthy and sensorineural hearing loss subjects with MEG. To compare the differences of the AEFs in left and right hemisphere. To compare the differences of the AEFs in healthy subjects at variable SPL. To compare the differences of the AEFs in sensorineural hearing loss subjects at variable SPL. To compare the differences of the AEFs evoked by pure tones in healthy and that in sensorineural hearing loss subjects with MEG.Materials and Methods: There were two groups in this study, which included 10 healthy medical student subjects and 10 sensorineural hearing loss middle school student subjects. Every healthy subject received stimuli of 1kHz tone bursts delivered to the bilateral ear at duration 8ms, ISI Is and SPL 30dB and 90dB; The SPL of tone bursts that every hearing loss subjects received were sub-, iso- and super- to each one's hearing threshold. All subjects examined with 306-channel whole-scalp neuromagnetometer of 4D-Neuroimaging and 1.5T MRI scanner of GE, and the data was processed with MEG-MRI Integration software. Results: In 10 normal-hearing controls the most evident AEFs evoked with pure tone was Ml00, which When superimposed on MRI located precisely on the Heschl's gyrus. Source strength of Ml00 in right hemisphere was stronger compared with that in left hemisphere, and the Ml00 of right hemisphere had shorter latencies than that in left hemisphere. When the AEFs evoked with 30dB and 90dB pure tones were compared, we found that the Ml00 of 90dB had shorter latencies and stronger strength than that of 30dB. But there was no significantly different from the location of Ml 00 ECD in 30dB and 90dB tones. In 10 sensorineural hearing loss subjects no AEFs evoked with pure tone at... |
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