Abnormal spontaneous neural activity in auditory cortex and auditory pathway of tinnitus: a resting-state fMRI study

This resting-state functional magnetic resonance imaging (rs-fMRI) study in tinnitus patients was conducted to observe the spontaneous neural activity of the central auditory system using a derived index, mean amplitude of low-frequency fluctuation (mALFF). Tinnitus subjects with right-ear hearing impairment (THL) and without hearing loss (TNH) and two age-, sex-, and education-matched control groups (NC1 and NC2) were recruited for rs-fMRI. mALFF maps of the tinnitus and matched NC groups were plotted in the central auditory system, including the primary auditory cortex (PAC), higher auditory cortex (HAC), and hubs of the central auditory pathway. mALFF values of the activity clusters in the central auditory system of THL and TNH patients were extracted and correlated with each clinical characteristic. Significantly increased mALFF clusters were found in bilateral PAC and HAC of THL-NC1 maps and in the left inferior colliculus and right HAC of TNH-NC2 maps. Thus, subgroups of tinnitus with and without hearing impairment might exhibit different homeostatic plasticity in the central auditory system. mALFF values of aberrant active clusters in the central auditory system are partly associated with specific clinical tinnitus characteristics.