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Functional imaging techniques might be considered as the best research tool for tinnitus because of the safe and noninvasive applicability to human.Steady-state studies using FDG-PET and SPECT-Tc99 have commonly reported the increased metabolism in the limbic system and the left primary auditory cortex (PAC) of tinnitus patients, regardless of their tinnitus-side.When the loudness of tinnitus was modulated by somatosensory stimulation or systemic injection of lidocaine, the primary and secondary AC, frontal lobe, and limbic system (contralateral to the tinnitus-side) showed corresponding changes in H215O-PET studies.Most fMRI studies had proposed a common hypothesis, The higher level of spontaneous activity in the auditory system of patients with tinnitus should induce larger sound-evoked neural responses compared to normal controls. However, the applied sound-stimuli could possibly elicit masking-residual inhibition to tinnitus, and hyperacusis (by definition) could also induce hypersensitive response to the stimuli.Our recent study clearly proved that the amount of sound-evoked neural response of tinnitus patients were not different from normal controls, unless hyperacusis were accompanied.It suggested that resting or steady state neuronal activity should be investigated rather than sound-evoked signal changes by using fMRI, therefore new fMRI analysis methods such as independent component analysis and functional connectivity analysis have been lately adopted for fMRI studies on tinnitus.Numerous imaging studies on tinnitus have been reported, however, it is necessary to be careful in interpretation of their results.Because most studies were not appropriately controlled, lacking in accurate matching of age, sex, level of hearing, sound-intolerance and psychological stress.The great inter-subject variability in size, shape and distribution of koniocortex of the auditory cortex should be considered in studying functional symmetry of the left and the right.In addition, the limited measurement to cortical areas might not be enough to comprehensively understand tinnitus-related neural and cognitive changes.