A Comparison of Averaged Evoked Potentials Recorded from Auditory Nerve Region and Brain Cortex in Waking Monkeys

Abstract

Squirrel monkeys were fitted permanently with rigid depth electrodes having tips localized in the auditory nerve region and with screw-type electrodes fixed on the surface of the parietal brain area (“vertex”). Summed records of pure-tone evoked potentials were recorded from both electrode sites using either a digital or an analog signal averager. Compared with cortical AERs, nerve evoked potentials showed greater amplitudes, greater resistance to habituation, less test-retest variability, and were characterized by less ambiguous waveforms at near-threshold levels. Acuity functions based on nerve AERs generally show greater sensitivity (lower detection levels) than those based on brain cortex responses.