Top-down and bottom-up regulated auditory phantom perception

Auditory phantom percepts such as tinnitus are associated with auditory deafferentation. The idea is that auditory deafferentation limits the amount of information the brain can acquire to make sense of the world. Because of this, auditory deafferentation increases the uncertainty of the auditory environment. In order to minimize uncertainty, the deafferented brain will attempt to obtain or fill in the missing information. Depending on the presence of hearing loss, two different kinds of tinnitus can be discerned, namely an auditory cortex related tinnitus associated with mild hearing loss and a parahippocampal cortex related tinnitus associated with more severe hearing loss. The weakness of this compensation model is that it cannot explain why some people without hearing loss develop tinnitus while conversely others with hearing loss do not develop tinnitus. In this study, we provide evidence for a top-down related tinnitus associated with a deficient top-down noise-cancelling mechanism, different from bottom-up related tinnitus. A total of 72 participants (age: 40.96 + 7.67 years; males: 48; females: 24) were recruited for this study. We demonstrate that top-down related tinnitus is related to a change in the pregenual anterior cingulate cortex that corresponds to increased activity in the auditory cortex. This is in accordance with the idea that tinnitus can have different generators as proposed in a recent model that suggest different compensation mechanisms at a cortical level can be linked to phantom percepts.