Vocalization elicited by activation of A delta- and C-fibres in the rat

Complex vocal responses in both the audible and ultrasonic frequency ranges were elicited by a single 2 ms electrical pulse applied to the tail. The first two cries exhibited consistent latencies and durations, were intensity-dependent and were triggered by peripheral fibres with conduction velocities of 7.3 +/- 0.8 and 0.7 +/- 0.1 ms-1, respectively. These behavioural responses are reminiscent of first and second pain triggered by A delta- and C-peripheral fibres in humans. They were followed by irregular audible cries with a fundamental frequency of 1.5 kHz and '22 kHz ultrasonic calls'.