gms | German Medical Science

Introduction: In cases of severe hearing loss or deafness the hearing ability can be restored in parts, for example, by using a cochlear implant (CI). The challenge is to objectively measure and verify whether the stimulation of the CI reaches the auditory cortex (AC) and induces the desired neural activity. Hence, a reliable method for the verification of AC activation is needed. One possible way for measuring cortical activity is functional magnetic resonance imaging (fMRI). However, beside accessibility issues also the magnetic parts of the CI preclude the general use of fMRI assessment. Therefore other, also repeatedly and frequently usable methods have to be investigated.

Methods: Functional near-infrared spectroscopy (fNIRS), which can be used also in combination with other modalities (multimodal recording, e.g. EEG), seems therefore a promising approach. fNIRS is an emerging non-invasive optical technique for the in-vivo assessment of cerebral oxygenation (changes of oxy- and deoxygenated hemoglobin) which is strongly correlated with the fMRI-BOLD signal. In recent years, multichannel fNIRS has been used to study functional activity of the cortex using different neurophysiological tasks. In this work a general overview of the technical setup of the multimodal recording environment is presented.

Results: First measurements were performed with the main focus to evaluate the principle performance of the fNIRS system. Results show comparable results in signal quality, spatio-temporal resolution and recorded activation patterns to previous work, as well as, other systems [1], [2], [3].

Conclusion: On this basis, next steps include the implementation of different paradigms for AC investigation, measurements in normal-hearing adults using various paradigms, and the generation of normative data of AC activation.

Supported by: Exzellenzcluster Hearing4all (EXC 1077/1)