Biomaterial Database

Consequences of chronic extracochlear electrical stimulation in neonatally deafened cats. 1995

P A Leake, and R L Snyder, and G T Hradek, and S J Rebscher

Department of Otolaryngology, University of California San Francisco 94143-0526, USA.

This investigation examined the consequences of neonatal deafness and chronic electrical stimulation of the cochlea in the developing auditory system. Cats were bilaterally deafened by daily ototoxic drug administration for two weeks after birth. Electrical stimulation was initiated at 6-9 weeks of age and continued for up to 6 months, using monopolar round window electrodes that synchronously excited auditory neurons throughout the cochlea. Morphometric evaluation of the density of spiral ganglion cell somata within Rosenthal's canal demonstrated that chronic stimulation induced an increase of about 6% in neuronal survival. Although this difference was statistically significant, extracochlear stimulation in these cats was less effective in preventing neural degeneration than lower intensity, more restricted intracochlear stimulation that was shown in a previous study to induce an average increase of about 13% in neuronal survival. Electrophysiological recording experiments conducted in the inferior colliculus in these animals indicated that monopolar extracochlear stimulation can induce profound alterations in the spatial (frequency) selectivity of the auditory midbrain. On average, results were similar to those previously reported for bipolar intracochlear stimulation, showing about a two-fold expansion of the central representation of chronically stimulated electrodes. However, results with extracochlear stimulation showed much greater variability among individual animals. The results presented suggest that it is problematic to effect consistent 'whole' nerve stimulation using monopolar round window electrodes. Moreover, this mode of stimulation can induce profound functional alterations in the central nervous system and is substantially less effective in forestalling the degeneration of auditory neurons than intracochlear stimulation. Both these results contraindicate the implantation of such electrodes in young children for the purpose of maintaining the integrity of the auditory system for later application of a multichannel cochlear implant.

UI	MeSH Term	Description	Entries
D007245	Inferior Colliculi	The posterior pair of the quadrigeminal bodies which contain centers for auditory function.	Colliculus, Inferior,Brachial Nucleus of the Inferior Colliculus,Caudal Colliculus,Colliculus Inferior,Inferior Colliculus,Posterior Colliculus,Colliculi, Inferior,Colliculus Inferiors,Colliculus, Caudal,Colliculus, Posterior,Inferior, Colliculus,Inferiors, Colliculus
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009355	Neomycin	Aminoglycoside antibiotic complex produced by Streptomyces fradiae. It is composed of neomycins A, B, and C, and acts by inhibiting translation during protein synthesis.	Fradiomycin Sulfate,Neomycin Palmitate,Neomycin Sulfate
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D002415	Cats	The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003051	Cochlea	The part of the inner ear (LABYRINTH) that is concerned with hearing. It forms the anterior part of the labyrinth, as a snail-like structure that is situated almost horizontally anterior to the VESTIBULAR LABYRINTH.	Cochleas
D003054	Cochlear Implants	Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.	Auditory Prosthesis,Cochlear Prosthesis,Implants, Cochlear,Auditory Prostheses,Cochlear Implant,Cochlear Prostheses,Implant, Cochlear,Prostheses, Auditory,Prostheses, Cochlear,Prosthesis, Auditory,Prosthesis, Cochlear
D003638	Deafness	A general term for the complete loss of the ability to hear from both ears.	Deafness Permanent,Hearing Loss Permanent,Prelingual Deafness,Deaf Mutism,Deaf-Mutism,Deafness, Acquired,Hearing Loss, Complete,Hearing Loss, Extreme,Acquired Deafness,Complete Hearing Loss,Deafness, Prelingual,Extreme Hearing Loss,Permanent, Deafness,Permanent, Hearing Loss,Permanents, Deafness
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.