Almost everyone is ticklish. When they scratch the soles of their feet and armpits, people will laugh because of itching. What is the reason? Recently, British female scientist Boomer conducted an experiment on six volunteers at the University of London, which revealed the mystery. Bummer first scratched the palm or foot of the subject with a machine, and recorded the changes of human brain current with a vibrator. Then let the subjects tickle themselves and record the current changes. Experiments show that when people tickle themselves, their cerebellum will send a signal telling other parts of the brain not to respond to this stimulus; But when others tickle, even if they tell the subjects in advance, the cerebellum will not send out a signal, and the brain will respond immediately to external stimuli, and people will laugh because of itching.