Binaural interactions in the auditory midbrain with bilateral electric stimulation of the cochlea

Bilateral cochlear implantation seeks to restore the advantages of binaural hearing to the profoundly deaf by giving them access to binaural cues normally important for accurate sound localization and speech reception in noise. This thesis characterizes binaural interactions in auditory neurons using a cat model of bilateral cochlear implants. Single neuron responses in the inferior colliculus (IC), the main nucleus of the auditory midbrain, were studied using electric stimulation of bilaterally implanted intracochlear electrode arrays. Neural tuning to interaural timing difference (ITD) was emphasized since it is an important binaural cue and is well represented in IC neural responses. Stimulation parameters were explored in an effort to find stimuli that might result in the best ITD sensitivity for clinical use. The majority of IC neurons were found to be sensitive to ITD with low-rate constant-amplitude pulse trains. Electric ITD tuning was often as sharp as that with acoustic stimulation in normal-hearing animals, but many neurons had dynamic ranges of ITD sensitivity limited to a few decibels. Consistent with behavioral results in bilaterally implanted humans, neural ITD discrimination thresholds degraded with increasing pulse rates above 100 pulses per second (pps).

Department dc:contributor.department

Harvard University--MIT Division of Health Sciences and Technology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Smith, Zachary M. (Zachary Mark)

Advisor dc:contributor.advisor

• Bertrand Delgutte.

• Harvard University--MIT Division of Health Sciences and Technology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/36166

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/36166