gms | German Medical Science

80th Annual Meeting of the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

German Society of Oto-Rhino-Laryngology, Head and Neck Surgery

20.05. - 24.05.2009, Rostock

Auditory Midbrain Implant: Effects of multi-site stimulation of the inferior colliculus on the primary auditory cortex

Meeting Abstract

  • corresponding author Roger Calixto - MHH HNO-Klinik, Hannover
  • Hubert H. Lim - MHH HNO-Klinik, Hannover
  • Anke Neuheiser - MHH HNO-Klinik, Hannover
  • Guenter Reuter - MHH HNO-Klinik, Hannover
  • Thomas Lenarz - MHH HNO-Klinik, Hannover
  • Minoo Lenarz - MHH HNO-Klinik, Hannover

Deutsche Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie. 80. Jahresversammlung der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie. Rostock, 20.-24.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09hnod039

doi: 10.3205/09hnod039, urn:nbn:de:0183-09hnod0392

Published: April 17, 2009

© 2009 Calixto et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Introduction:The auditory midbrain implant (AMI), designed for electrical stimulation of the inferior colliculus central nucleus (ICC) for hearing restoration, is now in clinical trials. However, since the ICC is a complex 3-D structure, we investigated in an animal model if further improvements may be achieved by stimulating across multiple regions of the ICC.

Methods: Two single shank arrays were inserted along the tonotopic gradient of the ICC in guinea pigs. We then recorded auditory cortical responses to electrical stimulation of two ICC sites within the same frequency lamina and with varying inter-site delays and levels. Finally we compared the cortical responses with multi-site stimulation (MSS) to single site stimulation (SSS) to assess which parameters provide better frequency tuning and safety per given cortical response.

Results: Frequency specificity was maintained with MSS in both cortical evoked potentials and spike activity. For any given spike rate MSS was seen to require less stimulation current per site. Placement effects were also observed, where stimulating a rostral site prior to a caudal site elicited a non-linear cortical response (and vice-versa). Finally, the effect of inter-stimulus-delay (ISD) was seen to create either facilitation or inhibition of the cortical response, depending on the relative delay used.

Conclusion: Paradigms with MSS provide benefits over SSS. They provide more specific responses (less spread) with more safety for a given cortical response. Possibly ISDs can be used to elicit variable percepts by controlling the enhancement/suppression interactions observed. Finally, MSS also permits interleaved stimulation where an overall stimulation rate can be increased while minimizing local adaptation.

Unterstützt durch: Cochlear Ltd.