Medial olivocochlear reflex interneurons are located in the posteroventral cochlear nucleus: a kainic acid lesion study in guinea pigs.
The medial olivocochlear (MOC) reflex arc is probably a three-neuron pathway consisting of type I spiral ganglion neurons, reflex interneurons in the cochlear nucleus, and MOC neurons that project to the outer hair cells of the cochlea. We investigated the identity of MOC reflex interneurons in the cochlear nucleus by assaying their regional distribution using focal injections of kainic acid. Our reflex metric was the amount of change in the distortion product otoacoustic emission (at 2f(1)-f(2)) just after onset of the primary tones. This metric for MOC reflex strength has been shown to depend on an intact reflex pathway. Lesions involving the posteroventral cochlear nucleus (PVCN), but not the other subdivisions, produced long-term decreases in MOC reflex strength. The degree of cell loss within the dorsal part of the PVCN was a predictor of whether the lesion affected MOC reflex strength. We suggest that multipolar cells within the PVCN have the distribution and response characteristics appropriate to be the MOC reflex interneurons.
de Venecia
Ronald K
RK
Department of Otology and Laryngology, Harvard Medical School, and Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114, USA.
Liberman
M Charles
MC
Guinan
John J
JJ
Brown
M Christian
MC
D000161:Acoustic Stimulation / Q000379:methods; D000818:Animals; D001306:Auditory Pathways / Q000033:anatomy & histology / Q000502:physiology; D003055:Cochlear Microphonic Potentials; D017626:Cochlear Nucleus / Q000033:anatomy & histology / Q000166:cytology* / Q000293:injuries / Q000502:physiology; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D007839:Functional Laterality / Q000502:physiology; D006168:Guinea Pigs; D007395:Interneurons / Q000145:classification / Q000502:physiology*; D007608:Kainic Acid / Q000633:toxicity*; D009433:Neural Inhibition / Q000502:physiology; D016571:Neural Networks, Computer; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D018690:Excitatory Amino Acid Agonists; D007608:Kainic Acid