Abstract
The marmoset (Callithrix jacchus) is a valuable non-human primate model for studying behavioral and neural mechanisms related to vocal communication. It is also well suited for investigating neural mechanisms related to cochlear implants. The purpose of this study was to characterize marmoset temporal bone anatomy and investigate the feasibility of implanting a multi-channel intracochlear electrode into the marmoset scala tympani. Micro computed tomography (microCT) was used to create high-resolution images of marmoset temporal bones. Cochlear fluid spaces, middle ear ossicles, semicircular canals and the surrounding temporal bone were reconstructed in three-dimensional space. Our results show that the marmoset cochlea is ∼16.5 mm in length and has ∼2.8 turns. The cross-sectional area of the scala tympani is greatest (∼0.8 mm 2) at ∼1.75 mm from the base of the scala, reduces to ∼0.4 mm 2 at 5 mm from the base, and decreases at a constant rate for the remaining length. Interestingly, this length-area profile, when scaled 2.5 times, is similar to the scala tympani of the human cochlea. Given these dimensions, a compatible multi-channel implant electrode was identified. In a cadaveric specimen, this electrode was inserted 3/4 turn into the scala tympani through a cochleostomy at ∼1 mm apical to the round window. The depth of the most apical electrode band was ∼8 mm. Our study provides detailed structural anatomy data for the middle and inner ear of the marmoset, and suggests the potential of the marmoset as a new non-human primate model for cochlear implant research.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 37-44 |
| Number of pages | 8 |
| Journal | Hearing Research |
| Volume | 290 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - Aug 2012 |
Bibliographical note
Funding Information:This work was supported by a grant from the Kleberg Foundation to X. Wang and grants from the NIH National Institute on Deafness and Other Communication Disorders ( F31 DC010321 to L. Johnson and P30 DC005211 to the Center for Hearing and Balance at Johns Hopkins). We thank Haoxin Sun for assistance with Amira reconstructions of several temporal bone specimens. We also thank Zach Smith for assistance with obtaining Cochlear Ltd. electrodes, Ben Tsui and Jianhua Yu for help with CT imaging of the electrode-implanted marmoset cochlea, Jenny Estes and Nate Sotuyo for animal care, and Mohamed Lehar, Hakim Hiel and San San Yu for help with histology.