TY - JOUR
T1 - Vestibular evoked potentials in response to direct unilateral mechanical stimulation
AU - Coale, Franklin S.
AU - Walsh, Edward J.
AU - McGee, Joann
AU - Konrad, Horst R.
PY - 1989/3
Y1 - 1989/3
N2 - Evoked potentials produced by direct unilateral mechanical stimuiation of the cannulated horizontal semicircular canal were investigated parametrically in anesthetized adult cats (40 mg/kg pentobarbital). Stimuli were fluid pressure pulses in a closed hydraulic system (no net flow), which was coupled to the lateral semicircular canal near the ampulla. Hydraulic waveform output and fluid pressure was monitored In situ via a parallel hydraulic circuit during experiments. Maximum fluid displacement at the level of the horizontal canal was 0.025 microliters. The intensity, duration, and presentation rate of the stimulus were varied during experiments. Field potentials were recorded differentially using subdermal electrodes, with the active lead in the region of the mastoid referenced to a distant nasal site. A total of 256 trials was accumulated for each run using an averaging computer. Evoked responses were physiologically vulnerable and reproducible, with little variance among animals. Response amplitude Increased monotonically until saturation was noted and responses followed the temporal structure of the pressure wave. Polarity reversal with differir electrode placement suggests that the generator site lies within the mastoid. Buhner, intense broadband acoustic stimuli and eighth nerve sectioning did not affect the vestibular evoked potentials, but could be shown to abolish the auditory evoked potentials. Results of these experiments support the notion that vestibular evoked potentials are related to the first derivative of the pressure pulse waveforms. Future experiments will be directed toward the assessment of vestibular physiology and pharmacology with this evoked response method.
AB - Evoked potentials produced by direct unilateral mechanical stimuiation of the cannulated horizontal semicircular canal were investigated parametrically in anesthetized adult cats (40 mg/kg pentobarbital). Stimuli were fluid pressure pulses in a closed hydraulic system (no net flow), which was coupled to the lateral semicircular canal near the ampulla. Hydraulic waveform output and fluid pressure was monitored In situ via a parallel hydraulic circuit during experiments. Maximum fluid displacement at the level of the horizontal canal was 0.025 microliters. The intensity, duration, and presentation rate of the stimulus were varied during experiments. Field potentials were recorded differentially using subdermal electrodes, with the active lead in the region of the mastoid referenced to a distant nasal site. A total of 256 trials was accumulated for each run using an averaging computer. Evoked responses were physiologically vulnerable and reproducible, with little variance among animals. Response amplitude Increased monotonically until saturation was noted and responses followed the temporal structure of the pressure wave. Polarity reversal with differir electrode placement suggests that the generator site lies within the mastoid. Buhner, intense broadband acoustic stimuli and eighth nerve sectioning did not affect the vestibular evoked potentials, but could be shown to abolish the auditory evoked potentials. Results of these experiments support the notion that vestibular evoked potentials are related to the first derivative of the pressure pulse waveforms. Future experiments will be directed toward the assessment of vestibular physiology and pharmacology with this evoked response method.
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U2 - 10.1177/019459988910000302
DO - 10.1177/019459988910000302
M3 - Article
C2 - 2496377
AN - SCOPUS:0024603498
SN - 0194-5998
VL - 100
SP - 177
EP - 186
JO - Otolaryngology–Head and Neck Surgery
JF - Otolaryngology–Head and Neck Surgery
IS - 3
ER -