Fig. 1.

Successive eVAS ratings of thermal pain are shown for a single subject during a REDSTIM trial, starting in the middle of the test session and continuing through 6 cycles of desensitization and 5 cycles of sensitization. Ratings above 20 are shown as shaded circles and are labeled as periods of sensitization. The temperature at the beginning of each period of sensitization was equal to or higher than subsequent temperatures which decreased until a rating below the setpoint occurred. Initial ratings below 20 began new periods labeled as desensitization (open squares). The temperature at the beginning of each desensitization period was equal to or lower than subsequent temperatures which increased until a rating above the setpoint occurred, beginning a new period of sensitization.