[Functional MRI study of auditory cortical responses in normal subjects and unilateral sensorineural hearing loss subjects].

OBJECTIVE: Amplitude modulation of auditory cortical responses was evaluated with functional MRI (fMRI) in subjects of unilateral sensorineural hearing loss (USNHL) and those of normal hearing (NH). METHOD: Twenty-one subjects with USNHL and 11 with normal hearing were examined with fMRI in response to amplitude modulation tones of 500 Hz with the modulation frequency at 8 Hz. An event related design was combined with a sparse clustered volume acquisitioning paradigm in data collection in order to reduce the influence of acoustic scanner noise. SPM2 software was used for offline data analyzing. RESULT: Significant activation, including volume and intensity, were found in the temporal lobe of control subjects, and significant differences in the volume and intensity were noted between the contralateral and ipsilateral activated auditory cortexes in them, exhibiting clearly contralateral predominance. When the normal ear with unilateral sensorineural hearing loss received signals, while significant activations in bilateral auditory cortexes, greater activation in the contralateral auditory cortexes was found in the normal ear. CONCLUSION: The difference in the lateralization between the two groups suggests the plasticity of auditory cortex with unilateral sensorineural hearing loss.