Direct Recordings from the Auditory Cortex in a Cochlear Implant User

  • Kirill V. Nourski
  • Christine P. Etler
  • John F. Brugge
  • Hiroyuki Oya
  • Hiroto Kawasaki
  • Richard A. Reale
  • Paul J. Abbas
  • Carolyn J. Brown
  • Matthew A. HowardIII
Research Article


Electrical stimulation of the auditory nerve with a cochlear implant (CI) is the method of choice for treatment of severe-to-profound hearing loss. Understanding how the human auditory cortex responds to CI stimulation is important for advances in stimulation paradigms and rehabilitation strategies. In this study, auditory cortical responses to CI stimulation were recorded intracranially in a neurosurgical patient to examine directly the functional organization of the auditory cortex and compare the findings with those obtained in normal-hearing subjects. The subject was a bilateral CI user with a 20-year history of deafness and refractory epilepsy. As part of the epilepsy treatment, a subdural grid electrode was implanted over the left temporal lobe. Pure tones, click trains, sinusoidal amplitude-modulated noise, and speech were presented via the auxiliary input of the right CI speech processor. Additional experiments were conducted with bilateral CI stimulation. Auditory event-related changes in cortical activity, characterized by the averaged evoked potential and event-related band power, were localized to posterolateral superior temporal gyrus. Responses were stable across recording sessions and were abolished under general anesthesia. Response latency decreased and magnitude increased with increasing stimulus level. More apical intracochlear stimulation yielded the largest responses. Cortical evoked potentials were phase-locked to the temporal modulations of periodic stimuli and speech utterances. Bilateral electrical stimulation resulted in minimal artifact contamination. This study demonstrates the feasibility of intracranial electrophysiological recordings of responses to CI stimulation in a human subject, shows that cortical response properties may be similar to those obtained in normal-hearing individuals, and provides a basis for future comparisons with extracranial recordings.


averaged evoked potential cortical plasticity electrical stimulation electrocorticography high gamma intracranial electrophysiology 



We are indebted to our patient for making this work possible. We thank Haiming Chen, Rachel Gold, and Christopher Kovach for their help with data collection and analysis and Pascale Sandmann and Mitchell Steinschneider for their helpful comments. This study was supported by the National Institute on Deafness and Other Communication Disorders at the National Institutes of Health (grant number R01-DC04290), National Center for Research Resources and the National Center for Advancing Translational Sciences at the National Institutes of Health (grant number UL1RR024979), Hearing Health Foundation (Collette Ramsey Baker Award), and the Hoover Fund.


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Copyright information

© Association for Research in Otolaryngology 2013

Authors and Affiliations

  • Kirill V. Nourski
    • 1
  • Christine P. Etler
    • 2
  • John F. Brugge
    • 1
    • 4
  • Hiroyuki Oya
    • 1
  • Hiroto Kawasaki
    • 1
  • Richard A. Reale
    • 1
    • 4
  • Paul J. Abbas
    • 2
    • 3
  • Carolyn J. Brown
    • 2
    • 3
  • Matthew A. HowardIII
    • 1
  1. 1.Department of NeurosurgeryThe University of IowaIowa CityUSA
  2. 2.Department of Otolaryngology—Head and Neck SurgeryThe University of IowaIowa CityUSA
  3. 3.Department of Communication Sciences and DisordersThe University of IowaIowa CityUSA
  4. 4.Department of PsychologyUniversity of Wisconsin—MadisonMadisonUSA

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