Manninen, S., et al., Social Laughter Triggers Endogenous Opioid Release in Humans. The Journal of Neuroscience, 2017. 37 (25): p. 6125.
299
Wildgruber, D., et al., Different types of laughter modulate connectivity within distinct parts of the laughter perception network. PloS one, 2013. 8 (5): p. e63441.