CODY and Bickford1 have demonstrated that it is possible to measure hearing by means of electric currents from the cerebral cortex, known as cortical-evoked responses. This has provided an objective method (cortical audiometry) for testing hearing without the need of a conscious response by the patient. A similar test in laboratory animals could be significant in the evaluation of normal physiology, effects of various ototoxic drugs, acoustic trauma, and experimental operative procedures.
The introduction of computer techniques which allow the isolation of potentials evoked by sensory stimuli from the electroencephalographic background has provided the otologist with both a useful clinical and research tool. Averaged responses evoked by click stimuli have been recorded from the dura over the auditory cortex in anesthetized guinea pigs.2 However, it has been possible to obtain a small averaged cortical response to click stimuli in awake guinea pigs with scalp electrodes only during curarization.
Kern EB, Cody DTR, Bickford RG. Vertex-Response Thresholds to Pure Tones in Guinea Pigs. Arch Otolaryngol. 1969;90(3):315–325. doi:10.1001/archotol.1969.00770030317012
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