Effects of electrical stimulation of the inferior colliculus on 2f1-f2 distortion product otoacoustic emissions in anesthetized guinea pigs

The effects of electrical stimulation of the inferior colliculus (IC) on the activation of olivocochlear nerve fibers were investigated in guinea pigs in which the 2f1-f2 distortion product otoacoustic emissions (DPOAE) were recorded. Animals were anesthetized with ketamine (33 mg/kg) and xylazine (...

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Bibliographic Details
Published in:Hearing research 2002-08, Vol.170 (1-2), p.116-126
Main Authors: POPELAR, J, MAZELOVA, J, SYKA, J
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cochlea - drug effects
Cochlea - physiology
Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation
Efferent Pathways - drug effects
Efferent Pathways - physiology
Electric Stimulation
Fundamental and applied biological sciences. Psychology
Gentamicins - pharmacology
Guinea Pigs
Inferior Colliculi - physiology
Olivary Nucleus - drug effects
Olivary Nucleus - physiology
Otoacoustic Emissions, Spontaneous - physiology
Perceptual Distortion - physiology
Vertebrates: nervous system and sense organs
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Summary:The effects of electrical stimulation of the inferior colliculus (IC) on the activation of olivocochlear nerve fibers were investigated in guinea pigs in which the 2f1-f2 distortion product otoacoustic emissions (DPOAE) were recorded. Animals were anesthetized with ketamine (33 mg/kg) and xylazine (6.6 mg/kg). Bipolar electrical stimulation of the IC by a train of pulses with currents less than the threshold for evoking muscle twitches resulted in a small depression of the DPOAE amplitude by 0.1-2 dB. The maximal effect was observed when the stimulating electrodes were located in the rostro-medial or ventral parts of the IC. The suppression of electrically evoked DPOAE was similar to the DPOAE suppression produced by acoustical stimulation of the contralateral ear by a broad-band noise. Suppression of DPOAE amplitude in response to both acoustical and electrical stimulation was abolished 1-2 h after a single intramuscular injection of gentamicin (210-250 mg/kg). The results indicate that electrical stimulation of the IC can activate the efferent system and produce DPOAE changes by similar mechanisms as does acoustical stimulation of the contralateral ear.
ISSN:0378-5955
1878-5891
DOI:10.1016/S0378-5955(02)00397-0