Gustatory event-related potentials (ERPs) have been developed more than a decade ago. Although first studies were highly promising no clinical routine application has yet been reported. We aimed to use gustatory ERP in a clinical setting and to investigate, gender-related differences, concentration dependency, and their test-retest reliability. We further addressed the question whether investigations in patients with documented taste disorders provide meaningful results.
Seventeen healthy volunteers participated in two sessions. Acetic acid was presented to the left or right portion of the tongue; stimuli were embedded in a constantly flowing air stream. Subjects rated the stimulus intensity using visual analogue scales. Lateralized sour thresholds were established by means of a psychophysical taste test.
ERP amplitude P1 was largest at fronto-central recording sites while amplitude P2 had a parietal maximum. Women had shorter response latencies than men. Concentration-related differences were found for amplitudes P2, and for latencies P1, and N1. Shorter ERP response latencies were seen for stimulation of the right compared to the left side. Test-retest reliability was highest for the higher stimulus concentration, and highest coefficients of correlation were found for latencies of ERP peaks P1 and N1. Preliminary investigations in a patient with hemiageusia indicated the usefulness of gustatory ERPs in the diagnostic process, especially with regard to medico-legal cases.
In conclusion, the present work shows that gustatory ERP provide a relatively unbiased, reliable and easy approach to objective assessment of human taste function.