Revisiting the Relationship Between Electrogustometry and Sour Taste Perception

Abstract

Abstract:In a recent study Ellegård, Goldsmith, Hay, and Morton concluded that electrogustometry is neither mediated by sour taste receptors, nor reflects sour taste quality. While aspects of electric taste await a full explanation, such farreaching claims have significant implications for the future of electrogustometry in clinical practice. The current paper presents a critique of the grounds upon which the arguments were based, and suggests that these conclusions may be premature.Ellegård, Goldsmith, Hay and Morton [1] addressed the contention that taste perception with anodal electrogustometric stimulation is mediated via sour taste receptors. Their stated aim was to evaluate "to what extent electrogustometry relates to an ability to detect sour taste -rather than sweet, salt, or bitter." They reasoned that if anodal stimulation activates sour taste receptors, then the positive predictive values of electrogustometry should be better for sour taste perception than for other taste qualities. They correlated electrogustometric thresholds with visual analogue scale (VAS) ratings to whole mouth and regional applications of taste solutions provided by patients with various disorders that have the potential to affect taste. Because the pattern of predictive values did not favour sour taste they rejected the view that "electrogustometry is mediated by sour taste receptors or even that it reflects the sour taste quality" [1]. Instead they concluded that electrogustometry measures a function of taste perception different from that induced by chemical stimuli.Research has yet to provide definitive answers to some of the questions that are raised concerning electric taste. In the meantime the validity of the arguments upon which conclusions are based must be established, because conclusions such as those reached by Ellegård et al. have significant implications for the future of electrogustometry in clinical practice. Here I challenge the expectation that electrogustometric thresholds should be better predictors of VAS scores from sour-tasting stimuli than from other solutions. ELECTRICAL TASTE, SOUR TASTE, AND pHIt may be tempting to overlook the fact that although an electrogustometer provides a quantitative threshold estimate; the device does not directly measure a taste response. Instead it delivers a stimulus. The ensuing perceptual response is quantified using an operational definition: namely, the current required for a chosen percentage of stimulus detections. Classically the stimulus delivered via electrogustometry was *Address correspondence to this author at the Massey University Albany, Private Bag 102-904 North Shore MSC, Auckland, New Zealand; Tel: 64 9 4140800; Fax: 64 9 414 0831; E-mail: J.A.Stillman@massey.ac.nz referred to as an "adequate" stimulus in view of the liberation of protons in the vicinity of the anode [2]. Acids are, of course, proton donors, and their association with sour taste is reflected in the Latin root of the word acid meaning "to be sour". Sour or soapy tastes have been reported, de...

Decreased electrogustometric taste sensitivity in patients with acquired olfactory dysfunction

“…Previous studies have demonstrated increased EGM threshold with aging (14,15) or smoking (17) . While some studies favored the electric taste as a gustatory phenomenon (34)(35)(36) , others failed to show a significant correlation between electric and common chemical tastes (37)(38)(39) , signifying the unique nature of electric taste. In addition, electric stimulation may be contaminated by trigeminal activation (40) .…”