Back when my
mechanics teacher was a graduate at
Merton College,
Cambridge back in
the sixties he had a friend who was doing some research. He wanted to prove that
fear was caused by a chemical in the brain and so he was testing this theory on rats.
What he would do was scare them, BOO!, and then kill them. He would then perform a chemical analysis on their brains to try and find a chemical that could be responsible for the fear they had experienced before they died. However this proved unsuccessful and he thought it was most likely because the chemical dissipated before he was able to perform the analysis.
To counter this problem he designed a maze. The rats would scuttle through the maze until they got to a certain point where they would trigger a large sprung ball to jump out at them whilst making a very loud noise. The instant after the ball sprung out a trapdoor would open underneath them and they would be dropped into a container of liquid nitrogen thus freezing them and the chemical state of the brain.
Despite this ingenious technique he was never able to prove his theory.