The auditory midbrain implant (AMI), which consists of a single shank array designed for stimulation within the central nucleus of the inferior colliculus (ICC), has been developed for deaf patients who cannot benefit from a cochlear implant. Currently, performance levels in clinical trials for the AMI are far from those achieved by the cochlear implant and vary dramatically across patients, in part due to stimulation location effects. As an initial step towards improving the AMI, we investigated how stimulation of different regions along the isofrequency domain of the ICC as well as varying pulse phase durations and levels affected auditory cortical activity in anesthetized guinea pigs. This study was motivated by the need to determine in which region to implant the single shank array within a three-dimensional ICC structure and what stimulus parameters to use in patients. Our findings indicate that complex and unfavorable cortical activation properties are elicited by stimulation of caudal-dorsal ICC regions with the AMI array. Our results also confirm the existence of different functional regions along the isofrequency domain of the ICC (i.e., a caudal-dorsal and a rostral-ventral region), which has been traditionally unclassified. Based on our study as well as previous animal and human AMI findings, we may need to deliver more complex stimuli than currently used in the AMI patients to effectively activate the caudal ICC or ensure that the single shank AMI is only implanted into a rostral-ventral ICC region in future patients.
|Original language||English (US)|
|Number of pages||20|
|Journal||JARO - Journal of the Association for Research in Otolaryngology|
|State||Published - Dec 2010|
Bibliographical noteFunding Information:
We would like to thank Verena Scheper for assistance with animal surgeries and Cornelia Froemke (Center of Biometry, Medical Informatics and Medical Technology, Hannover Medical University) for assistance with data analysis. We would also like to thank James Patrick and Frank Risi (Cochlear Ltd., Lane Cove, Australia) for technical support with and development of the AMI array. This research was funded by Cochlear Ltd. and German Research Foundation (SFB 599).
- auditory brainstem implant
- auditory cortex
- auditory midbrain implant
- auditory thalamus
- cochlear implant
- deep brain stimulation