Spiral ganglion cell site of excitation I: Comparison of scala tympani and intrameatal electrode responses

• Published in: Hearing research Vol. 215; no. 1; pp. 10 - 21
• Main Authors: Cartee, Lianne A., Miller, Charles A., van den Honert, Chris
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2006; Elsevier
• Subjects: Algorithms; Animals; Auditory nerve; Biological and medical sciences; Cats; Cell Membrane - physiology; Chemical and industrial products toxicology. Toxic occupational diseases; Cluster Analysis; Cochlear implant; Cochlear Implants; Cochlear Nerve - physiology; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Electric Stimulation - methods; Electrical stimulation; Electrodes; Fundamental and applied biological sciences. Psychology; Medical sciences; Models, Neurological; Scala Tympani - innervation; Scala Tympani - physiology; Single fiber recording; Spiral Ganglion - physiology; Toxicology; Various organic compounds; Vertebrates: nervous system and sense organs; Cochlear implant; Electrical stimulation; Single fiber recording; Cats; Auditory nerve; Fissipedia; Spiral ganglion; Carnivora; Implant; Electrical stimulus; Axon; Algorithm; Modeling; Inner ear; Organ of hearing; Vertebrata; Mammalia; Cat; Cochlea; Auditory pathway; Excitation; Scala tympani; Summation
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/j.heares.2006.02.012

To determine the site of excitation on the spiral ganglion cell in response to electrical stimulation similar to that from a cochlear implant, single-fiber responses to electrical stimuli delivered by an electrode positioned in the scala tympani were compared to responses from stimuli delivered by an electrode placed in the internal auditory meatus. The response to intrameatal stimulation provided a control set of data with a known excitation site, the central axon of the spiral ganglion cell. For both intrameatal and scala tympani stimuli, the responses to single-pulse, summation, and refractory stimulus protocols were recorded. The data demonstrated that summation pulses, as opposed to single pulses, are likely to give the most insightful measures for determination of the site of excitation. Single-fiber summation data for both scala tympani and intrameatally stimulated fibers were analyzed with a clustering algorithm. Combining cluster analysis and additional numerical modeling data, it was hypothesized that the scala tympani responses corresponded to central excitation, peripheral excitation adjacent to the cell body, and peripheral excitation at a site distant from the cell body. Fibers stimulated by an intrameatal electrode demonstrated the greatest range of jitter measurements indicating that greater fiber independence may be achieved with intrameatal stimulation.