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Abstract:
Background: In recent years, human neuroimaging enhanced the understanding of neural mechanisms of tinnitus. However, each neuroimaging technique has specific limitations. Here, we provide first preliminary data in
tinnitus from functional near-infrared spectroscopy (fNIRS) - an optical, not magnetic approach to measure blood
oxygenation level dependent signals. fNIRS is a valid and
reliable method with limited spatial resolution, but was
shown to be capable to measure activity in auditory cortex.
Materials and Methods: White noise was presented in an
event-related (40 x 1.75s with 12-14s breaks) and blockwise
(12 x 20s with 20s breaks) manner in 40 patients with
tinnitus and 20 controls comparable for age and gender.
The fNIRS probe-sets (2 x 22 channels) were placed over
temporal areas.
Results: Preliminary analyses indicate that tinnitus was
associated with reduced auditory cortical oxygenation in
both designs in contrast to controls.
Conclusions: fNIRS is capable to add relevant information
to sound evoked activity in auditory cortex. Future studies
might be able to add more precise knowledge of auditory
cortex activity with respect to the laterality and the character of the tinnitus percept. fNIRS might also be valuable in measuring brain areas which are challenging measureable by functional magnetic resonance imaging, i.e., orbitalfrontal cortex due to susceptibility artefacts.In addition, further research should concentrate on resting state measurements or on combined fNIRS-EEG measurements
obliterating the limitations of both techniques.
