A comparatively recent electrophysiological technique for studying peripheral olfactory events is to record sustained negative potentials from the olfactory epithelium. This method is rapidly replacing the older technique of recording multifiber discharges from the olfactory nerve or bulb. Therefore, the extent to which the results from the two methods correlate with each other was studied by simultaneously recording from the nerve and from the mucosa under several conditions. Although most often parallel, some differences between the two measures were found. Their response maxima did not always temporally coincide. Their amplitudes did not always correlate. Certain stimuli reduced subsequent mucosal responses but not the neural. Repeated stimulation sometimes produced similar differences. Finally, the two responses were not linearly related as a function of stimulus intensity or flow rate. However, for reasons discussed, it is difficult to conclude that these discrepancies necessarily reflect unfavorably upon the reliability of the mucosal potential as the criterion measure of peripheral olfactory activity. Nevertheless, the mucosal potential should not be accepted unequivocally as such a criterion measure until it is more thoroughly understood.
