Cortical activation during a pitch discrimination task in tinnitus patients and controls--an fMRI study.

Chronic subjective tinnitus has been associated with aberrant activation of cortical areas involved in the perception of auditory information. This leads to the hypothesis that neural correlates of altered auditory perception may be found in tinnitus patients using functional magnetic resonance imaging. To study brain activation patterns due to acoustic stimulation in a pitch discrimination task, 6 tinnitus patients and 6 age-matched controls were investigated. Tones were presented binaurally at 5 beeps/s with three different frequencies in a block design. Using Statistical Parametrical Mapping, we found activation of secondary auditory areas in both groups. Furthermore, controls showed activation of the right-hemispheric anterior insula, whereas the middle frontal gyrus, putamen and left-hemispheric insula were activated in tinnitus patients. In the between-group analysis, activation of the caudate nucleus, superior frontal gyrus (Brodmann area 8) and cingular cortex was more pronounced in patients than in controls suggesting the perception of auditory inputs in a more emotional context in our patient group compared to controls.