Binaural interactions develop in the auditory brainstem of children who are deaf: effects of place and level of bilateral electrical stimulation

Bilateral cochlear implants (CIs) might promote development of binaural hearing required to localize sound sources and hear speech in noise for children who are deaf. These hearing skills improve in children implanted bilaterally but remain poorer than normal. We thus questioned whether the deaf and...

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Bibliographic Details
Published in:The Journal of neuroscience 2012-03, Vol.32 (12), p.4212-4223
Main Authors: Gordon, Karen A, Salloum, Claire, Toor, Gurvinder S, van Hoesel, Richard, Papsin, Blake C
Format: Article
Language:English
Subjects:
Acoustic Stimulation
Adolescent
Child
Child, Preschool
Cochlear Implantation - methods
Contingent Negative Variation - physiology
Deafness - physiopathology
Electric Stimulation - methods
Electroencephalography
Evoked Potentials, Auditory, Brain Stem - physiology
Female
Functional Laterality - physiology
Humans
Infant
Male
Psychoacoustics
Sound Localization - physiology
Speech Perception - physiology
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Summary:Bilateral cochlear implants (CIs) might promote development of binaural hearing required to localize sound sources and hear speech in noise for children who are deaf. These hearing skills improve in children implanted bilaterally but remain poorer than normal. We thus questioned whether the deaf and immature human auditory system is able to integrate input delivered from bilateral CIs. Using electrophysiological measures of brainstem activity that include the Binaural Difference (BD), a measure of binaural processing, we showed that a period of unilateral deprivation before bilateral CI use prolonged response latencies but that amplitudes were not significantly affected. Tonotopic organization was retained to some extent as evidenced by an elimination of the BD with large mismatches in place of stimulation between the two CIs. Smaller place mismatches did not affect BD latency or amplitude, indicating that the tonotopic organization of the auditory brainstem is underdeveloped and/or not well used by CI stimulation. Finally, BD amplitudes decreased when the intensity of bilateral stimulation became weighted to one side and this corresponded to a perceptual shift of sound away from midline toward the side of increased intensity. In summary, bilateral CI stimulation is processed by the developing human auditory brainstem leading to perceptual changes in sound location and potentially improving hearing for children who are deaf.
ISSN:0270-6474
1529-2401
DOI:10.1523/JNEUROSCI.5741-11.2012