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Chronically implanted epidural electrodes in Göttinger minipigs allow function tests of epiretinal implants

  • Thomas LaubeEmail author
  • Thomas Schanze
  • Claudia Brockmann
  • Ines Bolle
  • Thomas Stieglitz
  • Norbert Bornfeld
Laboratory Investigation

Abstract

Background

To test the function of implantable devices for electrical stimulation of the retina, long-term registration tests of cortical-evoked potentials are required. Skin electrodes are not appropriate to provide representative recordings, due to the voluminous pneumatic frontal sinus of minipigs. Therefore, epidural electrodes were permanently implanted in minipigs and tested with visual and electrical retinal stimulation. The present study describes long-term recordings of electrically evoked cortical potentials in minipigs.

Methods

Three-channel silver-silver chloride electrodes were fixed on the epidura dorsal to the primary visual cortex of one hemisphere in Göttinger minipigs. Repeated light stimulation was performed and platinum-polyimide film multielectrode arrays were implanted on the retina for electrical stimulation and were later removed. Cortical potentials were recorded after stimulation with short biphasic charge-balanced currents.

Results

For up to 18 months, the implanted epidural electrodes allowed recording of visual cortex potentials evoked by visual or electrical retina stimulation. Small changes of response amplitudes in subsequent experiments indicated a stable location and recording properties of the cortex electrodes. Visual stimulation often yielded stronger responses for the contralateral eye. Superthreshold electrical retina stimulation evoked cortical responses with less delay compared to visual stimulation. We found threshold currents of 50 µA for charge-balanced biphasic trains of current impulses. Postoperative examination showed an attached and unchanged retina.

Conclusions

The minipig model is appropriate for the implantation of epiretinal stimulation electrodes and for the long-term tests of retinal implants by recording of cortical responses with chronically implanted epidural electrodes.

Keywords

Retina Retinitis Pigmentosa Visual Stimulation Frontal Sinus Stimulation Current 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Notes

Acknowledgements

This study was supported by a grant from the German Federal Ministry for Education, Science, Research and Technology (BMBF) to the EPI-RET research group, Germany.

References

  1. 1.
    Chow AY, Chow VY (1997) Subretinal electrical stimulation of the rabbit retina. Neurosci Letters 225:13–16Google Scholar
  2. 2.
    Chow AY, Chow VY, Pardue MT, Perlman JI, Peachey NS (1998) Retinal and cortical potentials induced by subretinally implanted microphotodiode arrays. Invest Ophthalmol Vis Sci 39:S565Google Scholar
  3. 3.
    Delbeke J, Pins D, Michaux G, Wanet-Defalque MC, Parrini S, Veraart C (2001) Electrical stimulation of anterior visual pathways in ritinitis pigmentosa. Invest Ophthalmol Vis Sci 42:291–297PubMedGoogle Scholar
  4. 4.
    Eckhorn R, Stett A, Schanze T, Gekeler F, Schwahn H, Zrenner E, Wilms M, Eger M, Hesse L (2001) Physiologische Fuktionsprüfungen von Retinaimplantaten an Tiermodellen. Ophthalmologe 98:369–375CrossRefPubMedGoogle Scholar
  5. 5.
    Eckmiller R (1997) Learning retina implants with epiretinal contacts. Ophthalmic Res 29:281–289Google Scholar
  6. 6.
    Hesse L, Schanze T, Wilms M, Eger M (2000) Implantation of retina stimulation electrodes and recording of electrical stimulation responses in the visual cortex of the cat. Graefes Arch Clin Exp Ophthalmol 238:840–845Google Scholar
  7. 7.
    Humayun MS, de Juan E, Dagnelie G, Greenberg RJ, Probst RH, Phillips DH (1996) Visual perception elicited by electrical stimulation of retina in blind humans. Arch Ophthalmol 114:40–46Google Scholar
  8. 8.
    Li ZY, Wong F, Chang JH, Possin DE, Hao Y, Petters RM, Milam AH (1998) Rhodopsin transgenic pigs as a model for human retinitis pigmentosa. Invest Ophthalmol Vis Sci 39:808–819Google Scholar
  9. 9.
    Peixoto N, Straßburger S, Hornig R, Walter P, Szurman P, Eckmiller R (1998) Evaluation of implanted epiretinal microcontacts in the mammalian retina. Invest Ophthalmol Vis Sci 39:S902Google Scholar
  10. 10.
    Potts AM, Inoue J, Buffum D (1968) The electrically evoked response of the visual system (EER). Invest Ophthalmol 7:269–278PubMedGoogle Scholar
  11. 11.
    Rizzo JF, Wyatt J (1997) Prospects for a visual prosthesis. Neuroscientist 3:251–262Google Scholar
  12. 12.
    Schanze T, Wilms M, Eger M, Hesse L, Eckhorn R (2002) Activation zones in cat visual cortex evoked by electrical retina stimulation. Graefes Arch Clin Exp Ophthalmol 240:947–954PubMedGoogle Scholar
  13. 13.
    Schwahn HN, Gekeler F, Kohler K, Kobuch K, Sachs HG, Schulmeyer F, Jakob W, Gabel V-P, Zrenner E (2001) Studies on the feasibility of a subretinal visual prosthesis: data from Yucatan micropig and rabbit. Graefes Arch Clin Exp Ophthalmol 239:961–967PubMedGoogle Scholar
  14. 14.
    Stieglitz T, Beutel H, Schuettler M, Meyer JU (2000) Micromachined, polyimide-based devices for flexible neural interfaces. Biomed Microdevices 2:283–294CrossRefGoogle Scholar
  15. 15.
    Walter P, Heimann K (2000) Evoked cortical potentials after electrical stimulation of the inner retina in rabbits. Graefes Arch Clin Exp Ophthalmol 238:315–318PubMedGoogle Scholar
  16. 16.
    Zrenner E, Stett A, Weiss S, Aramant RB, Guenther E, Kohler K, Miliczek KD, Seiler MJ, Haemmerle H (1999) Can subretinal microphotodiodes successfully replace degenerated photoreceptors? Vision Res 39:2555–2567PubMedGoogle Scholar
  17. 17.
    Zrenner E (2002) Will retina implants restore vision? Science 295:1022–1025PubMedGoogle Scholar

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • Thomas Laube
    • 1
    Email author
  • Thomas Schanze
    • 3
  • Claudia Brockmann
    • 1
  • Ines Bolle
    • 2
  • Thomas Stieglitz
    • 4
  • Norbert Bornfeld
    • 1
  1. 1.Department of OphthalmologyUniversity of Essen EssenGermany
  2. 2.Central Animal LaboratoryUniversity of EssenEssenGermany
  3. 3.Department of Physics, NeuroPhysics GroupPhilipps UniversityMarburgGermany
  4. 4.Fraunhofer Institute for Biomedical EngineeringSt. IngbertGermany

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