Frontostriatal Gating of Tinnitus and Chronic Pain

Tinnitus and chronic pain are sensory-perceptual disorders associated with negative affect and high impact on well-being and behavior. It is now becoming increasingly clear that higher cognitive and affective brain systems are centrally involved in the pathology of both disorders. We propose that the ventromedial prefrontal cortex and the nucleus accumbens are part of a central 'gatekeeping' system in both sensory modalities, a system which evaluates the relevance and affective value of sensory stimuli and controls information flow via descending pathways. If this frontostriatal system is compromised, long-lasting disturbances are the result. Parallels in both systems are striking and mutually informative, and progress in understanding central gating mechanisms might provide a new impetus to the therapy of tinnitus and chronic pain. Ventromedial prefrontal cortex (vmPFC) and nucleus accumbens (NAc) in the ventral striatum form a frontostriatal gating system for the valuation and top-down modulation of sensory signals.A reduction in grey matter volume of medial prefrontal cortex, as determined with voxel-based morphometry, is one of the signature biomarkers of both tinnitus and chronic pain, although the exact location varies.Different subregions of the subcallosal region control tinnitus intensity and tinnitus distress: vmPFC is part of a gain control circuit; the subcallosal anterior cingulate cortex is responsible for negative valuation.Dopamine and serotonin act as neuromodulators of frontostriatal activity in chronic pain, and this may provide avenues for future treatment of both disorders.