Cochleotopic selectivity of a multichannel scala tympani electrode array using the 2-deoxyglucose technique

• Published in: Hearing research Vol. 59; no. 2; pp. 224 - 240
• Main Authors: Brown, M., Shepherd, R.K., Webster, W.R., Martin, R.L., Clark, G.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1992; Elsevier
• Subjects: 2-Deoxyglucose; Acoustic Stimulation; Animals; Auditory Pathways; Auditory Threshold - physiology; Autoradiography; Biological and medical sciences; Cats; Cochlear nucleus; Cochlear prostheses; Deoxyglucose - metabolism; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Electric Stimulation; Electrical stimulation; Electrodes; Evoked Potentials, Auditory, Brain Stem; Fundamental and applied biological sciences. Psychology; Inferior Colliculi - metabolism; Inferior colliculus; Nerve Fibers - physiology; Rhombencephalon - metabolism; Rhombencephalon - physiology; Scala Tympani - innervation; Scala Tympani - physiology; Vertebrates: nervous system and sense organs; 2-Deoxyglucose; Electrical stimulation; Cochlear prostheses; Inferior colliculus; Cochlear nucleus; Fissipedia; Carnivora; Vertebrata; Mammalia; Acoustic stimulus; Evoked potential; Electrical stimulus; Cat; Ear; Cochlea; Scala tympani; Organ of hearing
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(92)90119-8

The 2-deoxyglucose (2-DG) technique was used to study the cochleotopic selectivity of a multichannel scala tympani electrode array in four cats with another acting as an unstimulated control. Each animal was unilaterally deafened and a multichannel electrode array inserted 6 mm into the scala tympani. Thresholds to electrical stimulation were determined by recording electrically evoked auditory brainstem responses (EABRs). Each animal was injected with 2-DG, and electrically stimulated using bipolar electrodes located either distal or proximal to the round window. The contralateral ear was stimulated with acoustic tone pips at frequencies that matched the electrode place. Stimulation of both distal and proximal bipolar electrodes at 3 x EABR threshold, evoked localized 2-DG labelling in both ipsilateral cochlear nucleus (CN) and the contralateral inferior colliculus (IC), which was very similar in orientation and breadth to labelling evoked by the contralateral tone pips. The cochleotopic position of labelling to proximal stimulation was located in the 24–26 kHz region of each structure, whereas the distal labelling was located around 12 kHz. Distal stimulation at 10x EABR threshold produced very broad 2-DG labelling in IC centered around the 12 kHz place. The present 2-DG results clearly illustrate cochleotopic selectivity using multichannel bipolar scala tympani electrodes. The extent of this selectivity is dependent on electrical stimulus levels. The 2-DG technique has great potential in evaluating the efficacy of new electrode array designs.