Responses by humans to oral chemical irritants as a function of locus of stimulation.

Abstract

Different areas of the mouth varied in responsiveness to chemical irritation. Subjects were stimulated with 7-mm filter-paper disks containing capsaicin or piperine, which are irritant components of red and black pepper, in seven different regions of the mouth. They reported intense sensations from stimulation of the tip of the tongue, side of the tongue, and posterior palate, all of which contain gustatory receptors, and less intense sensations from the cheek and anterior palate. Capsaicin produced relatively more intense responses from the lip and posterior tongue than did piperine. Sensations produced by stimulation of these small areas grew over time. The patterns of qualitative adjectives used to describe the sensations arising from the two compounds were not the same. These results suggest that irritative chemical stimuli may be qualitatively differentiable.