Evidence for Sorption as a Mechanism of the Olfactory Analysis of Vapours

Abstract

THE physiological basis for olfactory discrimination may involve at least two basic mechanisms which need not be mutually exclusive : (a) the receptors themselves may be more or less selectively sensitive to different groups of chemicals ; (b) the receptor sheet as a whole might separate chemical vapours by adsorption or absorption in a manner analogous to gas chromatography columns. There has been some supporting evidence for the first mechanism^1,2, and suggestive evidence for the second has recently been reported³. The evidence suggesting the second mechanism depends, in part, on sampling the activity from different regions of the frog olfactory mucosa by recording the discharges from two olfactory nerve branches (a lateral one and a medial one), which under a dissecting microscope appear to subserve different mucosal regions. That these branches do indeed subserve different mucosal regions is supported by recent electrical stimulation experiments. The antidromically conducted discharges in response to individual stimulation of the lateral and medial nerve branches were recorded by an electrode placed at several points on the epithelium. The discharge tracts for the two branches were quite separate and localized (Fig. 1).