2.2.1Electrogustometry
We have evaluated taste acuity with electrogustometry (EGM). Electrical stimuli were delivered using an electrogustometer (TR-06, Rion Co, Tokio, Japan) with a single, flat, circular stainless steel stimulus probe (5mm in diameter).
All subjects were instructed not to drink or eat for at least an hour before the beginning of the testing session. A 500-ms electric stimulus was applied, beginning at -6 dB and increasing up to +34 dB (3-400 μΑ) in 2dB-steps [12,13,15]. Thresholds were measured randomly on both sides of the tongue to avoid any possible bias. All six areas were tested with the same stimulus duration before proceeding with the application of a stimulus of different duration. The subject was kept unaware of whether the current was applied (blind test) as previously reported [11,12]. A two-alternative forced-choice initially ascending single-staircase detection was employed using a two-down, one-up rule [11,12].