Laughing Rats? Panksepp & Burgdorf (2000).Behavioural Brain Research. 115, 25-38.
Characteristics of 50-kHz ultrasonic chirp.
- Greater in isolate-reared animals.
- Reflect rewarding properties of tickling.
- Are reduced by fear-arousing stimuli (cat odors).
- Associated with light, nipping “play bites” (play solicitation?).
- Selective breeding produced high and low chirping tendencies to tickling within four generations.
- Glutamate and dopamine involvement?