Distribution of Fos-like immunoreactivity in the auditory pathway evoked by bipolar electrical brainstem stimulation.
OBJECTIVE
The auditory brainstem implant (ABI) represents a new modality for the treatment of patients deafened as a result of complete excision of a bilateral VIIIth nerve tumor. However, little work has been done on the effect of the ABI on the mammalian auditory pathway. The aim of this study was to demonstrate the effect of the ABI using Fos-like immunoreactivity.


METHODS
A bipolar electrode was implanted in the dorsal cochlear nucleus of bilaterally deafened Sprague-Dawley rats, and electrical stimulation was presented at an intensity four times that of threshold.


RESULTS
Fos-like immunoreactivity was induced in the neurons of various auditory brainstem nuclei and observed in the low-to-middle frequency area. In the ipsilateral dorsal cochlear nucleus, ipsilateral posterior ventral cochlear nucleus and bilateral inferior colliculus, Fos-like immunoreactive neurons were observed as a distinct banding pattern.


CONCLUSIONS
This study showed that Fos-like immunoreactivity was observed in the restricted area of the primary brainstem auditory pathway with the appropriate tonotopicity. These results indicate that the ABI can provide auditory information suitable for speech recognition.
Takagi
Hideo
H
Department of Otolaryngology, Tokyo Medical University, Tokyo 160-0023, Japan. Hideo32ENT@aol.com
Saito
Hiromistu
H
Nagase
Shigeyo
S
Suzuki
Mamoru
M
D000818:Animals; D038262:Auditory Brain Stem Implants; D001306:Auditory Pathways / Q000737:chemistry / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology; D017626:Cochlear Nucleus / Q000737:chemistry / Q000502:physiology*; D003638:Deafness / Q000209:etiology / Q000628:therapy*; D004558:Electric Stimulation; D005072:Evoked Potentials, Auditory / Q000502:physiology; D007150:Immunohistochemistry; D007245:Inferior Colliculi / Q000737:chemistry; D008297:Male; D009847:Olivary Nucleus / Q000737:chemistry; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis* / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013067:Speech Perception / Q000502:physiology; D013997:Time Factors
D016760:Proto-Oncogene Proteins c-fos