Olfactory receptor cell activity under electrical polarization of the nasal mucosa in the frog. II. Responses to odour stimulation.

The interactions between electrical polarizations of the olfactory epithelium and odour stimulations were investigated at the level of the extracellular spike activity of the receptor cells in the frog. 1. In most cases, surface positive polarizations enhanced the excitatory olfactory responses, negative polarizations suppressed these responses; both interactive effects were graded. 2. The response of receptor cells to electrical polarization was markedly reduced or suppressed for several seconds following olfactory stimulation. This effect and the time course of the recovery period depended on the nature and the concentration of the olfactory stimulus. 3. The decrease in electrical excitability seemed to be independent of whether the recorded neuron had responded or not to the prior olfactory stimulation. 4. It is suggested that the olfactory stimulation caused the total constant current to change its distribution in the different cell pathways. Changes in conductance induced by olfactory stimuli could implicate the supporting cells. 5. The experimental findings are discussed with reference to a model of receptor cell function that assumes a deep, axo-somatic localization of the action potential trigger-zone.