PD Dr. Eugen Diesch, Dr. André Rupp, Dr. Peter Schneider
Supported by a grant of the Deutsche Forschungsgemeinschaft (DFG - DI 497/3-2)
Both invasive animal and noninvasive human studies have provided evidence for an association of tinnitus and hyperreactivity. In humans, components of the auditory evoked potential and the auditory evoked magnetic field seem to show an amplitude increase for stimulus frequencies at and in the vicinity of the tinnitus frequency and a decrease for lower stimulus frequencies (Diesch, E., Struve, M., Rupp, A., Ritter, S., Hülse, M., Flor, H. 2004. Enhancement of steady-state auditory evoked magnetic fields in tinnitus. European Journal of Neuroscience 19(4): 1093-1104).
To further elucidate psychophysiological mechanisms of hyperreactivity, our experiments are designed to investigate the following issues:
(1) Is evoked signal amplitude sensitive to variables that are known to modulate tinnitus loudness, like acoustic masking and somatosensory co-stimulation?
(2) Is tinnitus associated with a change of the profile of reciprocal lateral inhibition between tonal frequencies?
(3) If tinnitus is associated with an altered equilibrium between excitatory and inhibitory processes, is this reflected in the shape of the gradients of facilitation and suppression that obtain when pairs or series of stimuli are presented?
(4) Are tinnitus-related changes (1-3) enhanced in musicians who, without tinnitus, show increased evoked signal amplitudes across the board?
(5) Is the evoked signal amplitude increase in tinnitus due to additive superposition of additional energy or rather the result of amplified phase resetting of spontaneous oscillatory activity?
(6) Is tinnitus associated with a change of the spectrum of spontaneous (EEG, MEG) activity?
(7) Are there neuroanatomical correlates of tinnitus or of a hypothetical disposition to develop tinnitus?
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