EVestG Recordings are Vestibuloacoustic Signals

A field potential can be defined as the ‘synchronous’ firing of many of vestibuloacoustic nerve fibres. Electrovestibulography has been considered as a method to record and detect vestibuloacoustic signals originating mainly from the vestibular system. A clear picture of the likely acoustic, vestibular or vestibuloacoustic origin and the physiologic basis of these field potentials is lacking. Recordings were conducted on anesthetized Guinea Pigs [ketamine (60 mg/kg) and xylazine (6 mg/kg)] to determine the origin of these minute spontaneous field potentials detected, recorded and averaged during Electrovestibulography recordings. Recordings were made with (1) normal hearing and balance (vestibular function), (2) following cisplatin deafening then (3) following both cisplatin deafening and gentamicin vestibular ablation. The detected minute spontaneous field potentials were determined to be both acoustic and vestibular in origin i.e., vestibuloacoustic. Based on the spontaneous activity of acoustic and vestibular nerve fibers arguments are presented that these field potentials are predominantly vestibular.