Poster #: 22
Topic: Clinical applications (incl. consciousness)
Wednesday, Sep 9, 2015
Mismatch-negativity response in individuals with central auditory implants
1Department of Neurology, Hannover Medical School, Hannover, Germany
2Department of Physics, Chemnitz University of Technology, Chemnitz, Germany
3Department of Otolaryngology, Hannover Medical School, Hannover, Germany
Auditory brainstem implants (ABI) and auditory midbrain implants (AMI) are designed for electrical stimulation within the cochlear nucleus or the inferior colliculus to partially compensate for hearing loss in patients with neural deafness. However, only a small number of ABI/AMI patients are able to understand speech without lip reading. The goal of our EEG study was to contribute to the better understanding of how electrical stimulation of the auditory brainstem/midbrain relates to cortical responses and hearing abilities in these individuals. Specifically, we aimed to assess the question whether a mismatch-negativity (MMN) response can be observed in ABI/AMI patients. We used a MMN paradigm to examine AMI (N=2) and ABI (N=5) patients who were presented with a sequence of standard sounds (p=0.68; 440Hz; 400ms) and four infrequent deviant sounds (each p=0.08). The deviant sounds differed from the standard sounds either in frequency (increment; two levels) or duration (decrement; two levels). Further, in a control block we presented the four deviant sounds in succession which allowed comparing the event-related potentials (ERPs) to physically identical sounds between the MMN and the control block. First results revealed a high degree of variability in ABI and AMI patients regarding behavioral discrimination ability and ERPs. Despite this variability, we found N1-ERPs in all patients. Further, we observed a MMN response in some ABI- and AMI patients, suggesting that the MMN can be used as an objective index of auditory discrimination ability in these individuals.