Minimal two-point discrimination in human tongue and palate.

The distribution of minimal two-point discrimination values on the tongue and soft palate was investigated in normal subjects using electric stimulation. It was performed using square pulses of 0.35 ms duration, a rate 10 Hz, a voltage between 3.5 and 7.0 with an average of 4.09 using two silver-silver chloride electrodes (tip diameter, 0.4 mm), and a strain-guage device to control crimping pressure. The spatial threshold was 1.650 +/- 0.433 mm at the tongue tip and 2.650 +/- 0.856 mm and 1.675 +/- 0.269 mm on the anterior margin of each side of the tongue. The soft palate and lingual dorsum were almost completely insensitive. Electric stimulation is a convenient method of measuring two-point limen values.